Beans (Snap)
Ed Peachey
Revised November 26, 2008
DTP: look at text file for this chapter to see in-text table in first S-metolachlor entry, which usually is NOT imported into INDD with the rest of the text. You will need to manually copy and paste table into INDD. Delete this red-text note
BEANS, SNAP―General Weed Management Strategy
According to USDA standards and processor quality control, harvested beans must be free of nightshade berries, Canada thistle buds, pigweed stems, and mustard pods. Crop rotations, close row spacings, early season weed control, and cultivation (except in rocky or clod soils) are combined with herbicides to minimize weed competition and contamination of product.
BEANS, SNAP―Site Preparation, Stale Seedbeds, and Selective Postemergence Applications
See “Site Preparation,” “Registered Uses for Glyphosate,” and “Registered Uses of Aim Herbicide in Food Crops” at the beginning of the Vegetables section in this handbook.
BEANS, SNAP―Preplant Incorporated
•  EPTC (Eptam 7E)
not adzuki, cow peas, lima beans, or flat-podded  beans, except Romano
Rate  3 to 4 lb ai/A (3.5 to 4.5 pints/A)
Time  Apply preplant to soil dry enough for thorough mixing; incorporate 2 to 3 inches deep immediately by cross-disking, rototilling, or subsurface application.
Remarks  Beans can be planted immediately; controls grasses and suppresses nightshade with no activity on smartweed.. Inhibits shoot growth.
Caution  Suppresses yellow nutsedge growth but does not kill tubers. In the Willamette Valley, experience suggests rates may be reduced to as low as 1.5 lb ai/A when mixed with trifluralin.  
Site of action  Group 8: lipid synthesis inhibitor but not an ACCase inhibitor
Chemical family  Thiocarbamate
•  halosulfuron-methyl (Sandea)
supplemental label for use with Eptam
Rate  0.038 to 0.075 lb ai/A (0.5 to 1 oz/A)
Time  Apply with Eptam and incorporate immediately to approximately 2 inches deep.
Remarks  Suppresses nutsedge and improves control of broadleaves such as pigweed and lambsquarters. 
Caution  Read the label carefully to understand risks of using this product. Crop growth may be stunted briefly after emergence and maturity may be delayed. Consult label for rotation crops, interactions with soil-applied organophosphate insecticides that may increase crop injury, and other precautions. Do not exceed 2 oz/A herbicide per year. 
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  S-metolachlor (Dual Magnum) or
•  metolachlor (Cinch, Dual, Me-Too-Lachlor, or Parallel)

Recommended S-metolachlor rates (pints/A)	

Soil OM		Soil texture	
		coarse	medium	fine	
<3%		1–1.33	1.33–1.67	1.33–1.67	
>3%		1.33	1.33–1.67	1.67–2	

Rate  0.98 to 1.95 lb ai/A (1 to 2 pints/A S-metolachlor). Products containing S-metolachlor, the more active isomer, require about 33% less product to achieve results comparable to metolachlor.
Time  Apply preplant within 14 days of planting and mechanically incorporate in top 2 inches of soil.
Remarks  May delay maturity and/or reduce yield if soil is cold and wet or if heavy rains fall after planting. Controls many summer annual grasses, pigweed other broadleaf weeds, but is weak on mustard weeds and nightshade. Inhibits roots and shoots.
Caution  Do not graze crop residue or feed canning wastes to livestock for 6 wk after treatment. Inhibits roots and shoots.
Site of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Chloroacetamide
•  trifluralin (Treflan)
Rate  0.5 to 0.75 lb ai/A (1 to 1.5 pints/A), depending on soil type
Time  Apply preplant and incorporate 2 to 3 inches deep within 24 hr or less by cross-disking or by using a power take-off (PTO) rotary tiller. Spray only once and avoid overlapping.
Remarks  Controls grasses and some broadleaf weeds such as lambsquarters, but nightshade is very tolerant. Erratic plant growth, enlarged stems below the soil surface, and poor root growth have been observed when maximum labeled rates were applied uniformly in fields with slight variations in soil type. Inhibits mitosis in shoots and roots.
Caution  Consult label for planting sensitive crops within 12 to 20 mo, especially cereals and grass seed. 
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
•  pendimethalin (Prowl 3.3EC or Prowl H2O)
Rate  Prowl 3.3EC―0.5 to 1.5 lb ai/A (1.2 to 3.6 pints/A), depending on soil type. Prowl H2O―0.95 to 1.4 lb/A (2 to 3 pints/A), depending on soil type.
Time  Label describes preplant incorporation, but crop injury and yield losses have been observed under cool, wet conditions.
Remarks  Adjust rates depending on soil texture and organic matter.
Caution  Do not feed bean vines or graze livestock in treated fields. Weak on mustard and composite (sunflower) weeds. (Inhibits mitosis in both shoots and roots.)
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
BEANS, SNAP―Preemergence Soil-applied
•  S-metolachlor (Dual Magnum or Cinch) or
•  metolachlor (Me-Too-Lachlor or Parallel)
Rate  0.95 to 1.9 lb ai/A (1 to 2 pints/A S-metolachlor). See table above under Preplant Incorporated.
Time  Apply preemergence after planting and activate with 0.5 inch overhead irrigation or rain.
Remarks May delay maturity and/or reduce yield if soil is cold and wet or if heavy rains fall after planting. Controls many summer annual grasses, pigweed other broadleaf weeds, but is weak on mustard weeds and nightshade. Inhibits roots and shoots.
Caution  Preharvest interval is 120 days for hay. 
Site  of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Chloroacetamide
•  lactofen (Cobra)
Oregon only
Rate  0.125 to 0.188 lb ai/A (8 to 12 fl oz/A)
Time  Apply within 48 hr after planting, followed by 0.25 to 0.5 inch rain or irrigation before beans crack soil and emerge.
Remarks  Controls pigweed and nightshade but is weak on lambsquarters and has no control of grasses and smartweed. 
Caution and restrictions  Hard-driving rain at emergence may splash Cobra-treated soil on snap beans, resulting in unacceptable damage. In most cases, however, this crop response is temporary, and beans quickly outgrow it without negative affects to yield or quality. Severe crop response can be aggravated if beans are already under stress at emergence. Avoid field conditions that do not favor quick snap bean emergence, including soil temperatures below 60°F, planting depth below 1.5 inches, and using rollers after planting that compact and seal the soil surface. Flat, sealed soil surfaces increase water ponding and splashing of treated soil during thunderstorms, splashing Cobra-treated soil directly onto plant leaves. Read groundwater advisory on label. Preharvest interval is 55 days.
Site of action  Group 14: inhibits protoporphyrinogen oxidase
Chemical family  Diphenylether
•  halosulfuron-methyl (Sandea)
Rate  0.375 to 0.75 lb ai/A (0.5 to 1 oz/A)
Time  Apply after planting but before soil cracks. Adjust rates, depending on soil texture and organic-matter content.
Remarks  Do not exceed 2 oz/A herbicide per year.
Caution  Crop growth may be stunted briefly after emerging. See label for rotation crops, interactions with soil-applied organophosphate insecticides that may increase crop injury, and other precautions.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  clomazone (Command 3ME)
Rate  0.15 to 0.25 lb ai/A (0.4 to 0.67 pint/A) Use lower rate on coarse soils and the higher rate on fine soils.
Time  After planting and before weed emergence.
Remarks  A microencapsulated (ME) formulation is registered for use, but experience in snap beans is lacking in the Pacific Northwest. Therefore, experiment on a small scale before treating whole fields. This formulation is designed to minimize drift and injury to adjacent fields and sites.
Caution  Clomazone has a residual or carryover of up to 16 mo that severely restricts crop rotations in the Pacific Northwest; see label for rotation crops before applying. Also, crops on sandy soils in other regions have been injured. Allow 300 ft between the application site and desirable crops. Do not apply upwind of sensitive crops such as berries and ornamentals.
Site of action  Group 13: inhibits DOXP synthase
Chemical family  Isoxazolidinone
BEANS, SNAP―Postemergence
•  bentazon (Basagran)
Rate  0.5 to 1 lb ai/A (1 to 2 pints/A)
Time  Apply to small, rapidly growing annual broadleaf weeds after first trifoliate bean leaf is fully expanded. Not effective if temperature drops below 50°F at night and in daytime does not exceed 70°F. Adjust rate depending on expected weather conditions: more for cold days, less for hot days.
Remarks  Controls some broadleaf weeds, including smartweed; suppresses nutsedge. Leaves may be temporarily yellow, bronzed, speckled, or burned, but beans usually continue growth with minimal delays in pod maturity. Inhibits photosynthesis.
Caution  Do not tank-mix with other pesticides or exceed 4 pints/A per season. Preharvest interval is 30 days.
Site of action  Group 6: photosystem II inhibitor
Chemical family  Benzothiadiazole
•  imazamox (Raptor)
 •  bentazon (Basagran) 
Rate  0.031 lb ai/A (4 oz/A) Raptor; 0.188 to 0.50 lbs ai/A (6-16 oz/A) Basagran
Time  Apply to snap beans in the first to second trifoliate leaf stage when most weeds are growing actively and less than 3 inches tall.
Remarks  Label requires application with 6 to 16 oz/A of Basagran. Adding Basagran as a tank-mix reduces the potential of crop injury. Follow label carefully for best results. Add a nonionic surfactant or crop oil. Use of a nitrogen-based fertilizer to improve weed control will improve grass control but must be measured against the potential for increased crop injury. If applying during very hot weather, it is best to eliminate nitrogen-based adjuvants and to use nonionic surfactant rather than crop oil concentrate. Avoid repeat applications to minimize chances of developing resistance to this family of herbicides. Do not apply to drought-stressed bean plants or plants with poor root development.
Caution  Injury symptoms such as shortened internodes and/or temporary yellowing may appear soon after treatment but disappear within several days as long as plants are not stressed. Do not tank-mix with any insecticide or fungicide. Avoid tank-mixes with other herbicides, such as Select and Poast, in most cases. Consult label for rotational crops and food or feed restrictions; this herbicide may persist for 26 mo.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor (imazamox); Group 6: photosystem II inhibitor (bentazon)
Chemical family  Imidazolinone and benzothiadiazole
•  sethoxydim (Poast)
Rate  Consult label; do not exceed 0.47 lb ai/A (2.5 pints/A) per application or 0.75 lb ai/A (4 pints/A) per year
Time  Apply at optimum growth stage listed on the label.
Remarks  Identify susceptible grasses and add 2 pints/A nonphytotoxic crop oil concentrate to improve leaf absorption. Control often is erratic on grasses stunted or stressed from drought, high temperatures, or low fertility. Resistant grasses include annual bluegrass and all fine fescues; quackgrass can be suppressed. Grass control may be reduced if applied with bentazon. Inhibits fatty acid production, cell membranes, and new growth.
Caution  Preharvest interval is 15 days.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione
•  quizalofop P-ethyl  (Assure II)
Rate  0.04 to 0.08 lb ai/A (6 to 12 fl oz/A)
Time  Apply to annual or perennial grasses listed on label at optimum use rates based on weed size.
Remarks  Always use either a nonionic surfactant at 1 quart/100 gal or a petroleum-based crop oil at 1 gal/100 gal. Grass control may be reduced if applied with bentazon. 
Caution  Do not exceed 14 fl oz/A per season. Preharvest interval is 15 days. Do not graze livestock in treated areas or feed forage or hay to livestock.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Aryloxyphenoxy propionate
•  clethodim (Select Max and others)
Rate  0.068 to 0.12 lb ai/A (9 to 16 oz/A on annual grasses; 12 to 16 oz/A on perennial grass weeds)
Time  Apply to actively growing grasses at recommended weed heights.
Remarks  Recommended surfactant is nonionic surfactant at 0.25%; do not add ammonium sulfate. Can be tank-mixed with bentazon (Basagran) at 9 to 16 oz/A and with imazamox at 9 to 12 fl oz/A. Use crop oil concentrate (1%) plus AMS (2.5 lb/A) with bentazon and NIS (0.25%) plus AMS (2.5 lb/A) with imazamox.
Caution  Do not exceed 32 fl oz/A per year. Allow at least 14 days between applications. Preharvest interval is 30 days. 
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione

breakhere  Herbicide Effectiveness on Weeds in Snap Beans

Weed	Soil applied	Postemergent	
	EPTC (Eptam)	lactofen (Cobra)	S-metolachlor 
(Dual) Magnum)	pendimethalin (Prowl)	trifluralin (Treflan)	S -metolachlor (Dual Magnum) 
+ EPTC (Eptam)	S-metolachlor (Dual Magnum) 
+ lactofen (Cobra)	EPTC (Eptam)  + 
lactofen (Cobra)	bentazon (Basagran)	glyphosate	imazamox + bentazona	paraquat	quizalofop (Assure)	sethoxydim (Poast)	
Annual Broadleaf Weeds
Groundsel
Senecio vulgaris 	
G	
F	
G	
F	
G	
G	
G	
G	
F	
E	
F	
G	
N	
N	
Knotweed
Polygonum spp.  	P	VP	G	G	G	G	G	G	G	G	P	F	N	N	
Lambsquarters
Chenopodium album 	G	F	P	E	G	G	E	G	F	E	G	G	N	N	
Mayweed (Dog fennel)
Anthemis cotula   	G	E	G	V	V	G	G	G	F	E	P	G	N	N	
Mustard
Brassica spp.  	G	G	G	G	P	G	G	G	F	E	E	P	N	N	
Nightshades
Solanum spp.  	G	E	P	VP	VP	F	E	E	F	E	E	G	N	N	
Pigweed (Powell amaranth)
Amaranthus powellii 	F	E	G	G	G	G	E	E	P	E	E	G	N	N	
Puncturevine
Tribulus terrestris 	P	P	P	P	P	P	P	P	G	G	G	G	N	N	
Purslane
Portulaca oleracea 	G	G	G	G	G	G	G	G	G	E	G	P	N	N	
Smartweed
Polygonum spp.  	VP	VP	P	G	F	P	F	VP	E	E	G	G	N	N	
Sowthistle
Sonchus spp.  	F	G	F	P	P	G	G	G	P	E	F	G	N	N	
Annual Grasses 
Barnyardgrass
Echinochloa crus-galli 	
E	
VP	
G	
G	
G	
G	
G	
G	
VP	
E	
G	
P	
E	
E	
Crabgrass
Digitaria spp.  	G	VP	E-G	E	G	G	G	G	VP	E	P	F	G	G	
Wild proso millet
Panicum miliaceum 	G	VP	F	G	G	F	P	G	VP	E	G	P	E	E	
Troublesome Perennials 
Bindweed
Convolvulus spp.  	
F	
F	
F	
VP	
F	
P	
P	
F	
F	
F	
F	
VP	
N	
N	
Canada thistle
Cirsium arvense 	VP	VP	VP	VP	VP	P	VP	VP	G	F	―	VP	N	N	
Nutsedge
Cyperus spp.  	P	VP	G	P	P	F	F	P	P	F	P	VP	N	N	
Quackgrass
Elytrigia repens 	G	VP	P	P	G	G	P	G	VP	G	P	VP	G	G	
E = excellent     G = good     F = fair     P = poor     VP = very poor     N = no control    (―) Information lacking     
a  Label requires that bentazon be tank-mixed with imazamox to improve crop safety and broaden weed control spectrum.

breakhere  Beets (Red or Table)
Ed Peachey
Revised November 26, 2008
BEETS, RED OR TABLE―Site Preparation,  Stale Seedbeds, and Selective Postemergence Applications
See “Site Preparation,” “Registered Uses for Glyphosate,” and “Registered Uses of Aim Herbicide in Food Crops” at the beginning of the Vegetables section in this handbook.
•  cycloate (Ro-Neet 6E)
Rate  3 to 4 lb ai/A (0.5 to 0.66 gal/A)
Time  Apply preplant to soil dry enough for thorough mixing and, within minutes after application, incorporate 2 to 3 inches deep by cross-disking or using a rotary tiller.
Remarks  Use on mineral soils only. Seed may be planted immediately.
Caution  Inhibits shoot growth.
Site of action  Group 8: lipid synthesis inhibitor but not an ACCase inhibitor
Chemical family  Thiocarbamate
BEETS, RED OR TABLE―Preemergence and Early Postemergence
•  pyrazon (Pyramin DF)
Rate  3 to 3.5 lb ai/A (4.6 to 5.4 lb/A)
Time  Apply either preemergence after planting beet seed or postemergence after two expanded true leaves and before weeds have more than two to four true leaves. Apply on moist soil surface and follow with light irrigation.
Remarks  If irrigation is impossible, shallow incorporation is required before weeds are 2 inches tall. West of Cascades, preemergence application is preferred if rain or irrigation is adequate. 
Caution  Do not use on sandy or loamy sand soils or on soils with more than 5% organic matter. See label for replanting table beets or sugar beets only.
Site of action  Group 5: photosystem II inhibitor
Chemical family  Pyridazinone 
•  S-metolachlor (Dual Magnum)
Oregon only, with indemnified label
Rate  0.64 lb ai/A (0.67 pint/A)
Timing  Make a single broadcast application of Dual Magnum to soil surface after planting but before weeds or crop emerge. For effective weed control, Dual Magnum must be applied to clean-tilled soil.
Remarks  Special local needs indemnified label (OR-060012). This label is available only through the Syngenta Farm Assist website (www.farmassist.com) by completing the following steps.
	1. Visit the website and register as a user.
	2. Click on the Sign-in button and enter your user name and password.
	3. Click on Products, then Syngenta Crop Protection, then Special Labels.
	4. Near the top of the page, in very small print, it says “if searching for indemnified labels, click here”. Do that.
	5. On the next screen, enter state (OR) and product (Dual Magnum) on the drop-down menus and click the Submit button.
	6. The next screen shows the available Dual Magnum 24C labels. Select the crop (beets, in this case). Click the Submit button.
	7. The indemnification agreement will come on the screen. Read it carefully, then click ‘I accept’ or ‘I decline’.
	8. The label(s) you selected will appear on the next screen. Print the label(s), which must be in your possession when you apply the herbicide.
Make uniform applications in at least 15 gal/A of water. A band application also may be used. Irrigate after application to activate the herbicide if rain is not expected. If the crop is irrigated, use 0.5 inch of water shortly after planting to incorporate herbicide. Excessive irrigation before crop emerges may increase risk of crop injury.
Research at OSU has demonstrated that tank-mixing 15 to 30 oz of Nortron with Dual Magnum can substantially improve hairy nightshade  control.
Caution  Do not mechanically incorporate Dual Magnum. Do not use Dual Magnum if the planting operation creates a furrow or trough over the seed row into which rain or irrigation water will collect and thus concentrate the herbicide over the row. Do not use on coarse soils with less than 1.5% organic matter. Do not use on soils with greater than 10% organic matter. Do not exceed 0.67 pint/A of Dual Magnum in any single application or in total applications per crop.
Site of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Chloroacetamide
•  ethofumesate (Nortron SC, Ethotron)
Rate  Preemergence―0.5 to 1 lb ai/A (16 to 32 fl oz/A); early postemergence―maximum rate is 5.25 fl oz/A at two- and four-leaf stage. Weed control diminishes in fine-texture soils and soils with high organic matter.
Time  Apply after planting and activate with at least 0.5 inch water.
Remarks  Do not use smaller than 50 mesh screen and avoid overlaps that may increase risk of crop injury. For postemergent applications, rain or irrigation within 6 hr after application reduces weed control. Controls black nightshade but may need to tank-mix with Spin-Aid (phenmedipham) to control hairy nightshade postemergence. 
Caution  May cause temporary leaf fusion, distortion, and stunting when used according to label directions and under normal growing conditions. If crop is lost due to unfavorable growth conditions after application, do not plant anything except sugar beets, table beets, onions, garlic, shallots, or ryegrass.
Site of action  Group 16: unknown
Chemical family  Benzofuran
•  clopyralid (Stinger)
Rate  0.093 to 0.187 lb ae/A (4 to 8 oz/A)
Time  Apply when beets are in the cotyledon to eight-leaf stage and when weeds are actively growing.
Remarks  Target weeds are hairy and black nightshade. Preharvest interval is 30 days.
Caution  Clopyralid will cause leaves to turn red with occasional epinasty. Use caution if tank-mixing with other herbicides. Crop-rotation intervals: 12 mo for sweet corn and up to 18 mo for Brassica (cole) crops, peas, potatoes, and tomatoes.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  phenmedipham (Spin-Aid)
Rate  0.5 to 1 lb ai/A (3 to 6 pints/A)
Time  Apply any time beets are past four- to six-leaf stage and before weeds are at the two-leaf stage. Results are best when weeds are at two-true-leaf stage.
Remarks  Avoid applying if weather may change rapidly from cool and cloudy to warm and sunny, or if beets are stressed from insect, disease, or cultivation injury. Tip burn or temporary growth retardation and chlorosis are possible, although plants usually recover within 10 days. 
Caution  Preharvest interval is 60 days. Avoid diluting herbicide more than 1 quart/7 gal water in spray tank because that can cause the chemical to precipitate. 
Site  of action  Group 5: photosystem II inhibitor
Chemical family  Phenylcarbamate 
•  phenmedipham + desmedipham (Betamix)
Rate  Two-leaf beets, 1.5 pints/A; four-leaf beets, 1.5 to 2.3 pint/A; six-leaf beets, 1.5 to 3 pints/A
Time  Two- to six-leaf beets.
Remarks  Avoid applying if weather may change rapidly from cool and cloudy to warm and sunny, or if beets are stressed from insect, disease, or cultivation injury. Tip burn or temporary growth retardation and chlorosis are possible, although plants usually recover within 10 days. 
Caution  Preharvest interval is 50 days. Do not apply when plants are wet with dew. Irrigation or rain within 6 hr may reduce efficacy.
Site of action  Group 5: photosystem II inhibitors
Chemical family  Phenylcarbamates 
•  clethodim (Select 2EC; Prism in Oregon only)
Rate  0.094 to 0.125 lb ai/A (6 to 8 fl oz/A Select 2EC)
Time  Apply to actively growing grasses at recommended weed heights.
Remarks  Add crop oil concentrate at 1% but do not add nitrogen fertilizer. Do not exceed 8 fl oz/A per season. Allow at least 14 days between applications.
Caution  See labels for maximum rates per application and season. Preharvest interval is 30 days. 
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione

breakhere  Brassica (Cole) Crops 
Broccoli, Chinese broccoli, Brussels sprouts, cabbage, Chinese cabbage (napa), cauliflower, and kohlrabi
(Brassica Head and Stem Subgroup 5A) 
Chinese cabbage (bok choy), collards, kale, mustard and turnip greens (Leafy Brassica Greens Subgroup 5B) 
Turnips, rutabaga, radish, Daikon radish, and horseradish (Brassica Crops of Root Vegetable Subgroup 1A)
 Subgroups as defined by U.S. Environmental Protection Agency   DTP: place this footnote at the bottom of page where this chapter begins; delete this red-text note

Ed Peachey
Revised November 26, 2008
BRASSICA CROPS―Site Preparation, Stale Seedbeds, and Selective Postemergence Applications
See “Site Preparation,” “Registered Uses for Glyphosate,” and “Registered Uses of Aim Herbicide in Food Crops” at the beginning of the Vegetables section in this handbook.
BRASSICA CROPS―Preplant-incorporated
•  trifluralin (Treflan 4L)
excluding horseradish and rutabaga
Rate  0.5 to 1 lb ai/A (1 to 2 pints/A), depending on whether the crop is direct-seeded or transplanted, and on soil texture and organic matter content.
Time  Apply as a preplant soil-incorporated treatment before planting or transplanting.
Remarks  Direct-seeded crops may be stunted if rates exceed limits for soil type and organic matter content or if soil texture varies greatly within a field. Consult label for soil type, OM content, and application instructions.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
•  bensulide (Prefar 4-E)
excluding rutabaga, radish, and horseradish
Rate  5 to 6 lb ai/A (5 to 6 quarts/A)
Time  Apply preplant and incorporate 1 to 2 inches deep simultaneously or immediately after application by cross-disking or using a power take-off rotary tiller.
Remarks  Consult label for planting sensitive crops after treatment.
Caution  Do not exceed one application every 12 mo. (Inhibits seedling roots.)
Site of action  Group 8: lipid synthesis inhibitor but not an ACCase inhibitor
Chemical family  Organophosphorus
BRASSICA CROPS―Preemergence Surface-applied 
•  bensulide (Prefar)
excluding rutabaga, radish, and horseradish
Rate  5 to 6 lb ai/A (5 to 6 quarts/A) 
Time  Apply before crop and weeds emerge, preferably soon after planting; follow with 1 inch of sprinkler irrigation.
Remarks  For furrow irrigation, thoroughly saturate bed top. Sometimes the first flush of weeds must be controlled with cultivation before herbicide begins to control grass. Note other comments above.
Site of action  Group 8: lipid synthesis inhibitor but not an ACCase inhibitor
Chemical family  Organophosphorus
•  S-metolachlor (Dual Magnum)
Oregon only, for direct-seeded turnip, rutabaga, and daikon radish only
Rate  0.64 lb ai/A (0.67 pint/A) 
Timing  Make a single broadcast application of Dual Magnum to soil surface after planting but before weeds or crop emerge. For effective weed control, Dual Magnum must be applied to clean-tilled soil.
Remarks  Special local needs indemnified label for turnip, rutabaga, and Daikon radish (OR-060012). The label is available through the Syngenta Farm Assist website (www.farmassist.com), which must be accessed to digitally sign the indemnification agreement or product liability waiver. See 釘eets (red or table)� chapter in the 天egetables� section in this handbook for how to acquire the label. Make uniform applications in at least 15 gal/A water. A band application may also be used. Irrigate after application to activate the herbicide if rain is not expected.
Caution  Excessive irrigation before the crop emerges may increase the risk of crop injury. Do not mechanically incorporate Dual Magnum. Do not use Dual Magnum if the planting operation creates a furrow or trough over the seed row into which rain or irrigation water will collect and thus concentrate the herbicide over the row. Do not use on coarse soils with less than 1.5% organic matter. Do not use on soils with greater than 10% OM. Do not exceed 0.67 pint/A Dual Magnum in any single application or in total per crop year. Preharvest interval is 60 days.
Site of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Chloroacetamide
•  S-metolachlor (Dual Magnum)
Oregon only, transplanted cabbage, including Chinese (napa)
Rate  0.48 to 1.27 lb ai/A (0.5 to 1.33 pints/A) 
Timing  Prior to transplanting, or broadcast postemergence application within 48 hr after transplanting.
Remarks  Special local needs indemnified label for cabbage (OR-070006). The label is available through the Syngenta Farm Assist website (www.farmassist.com), which must be accessed to digitally sign the indemnification agreement or product liability waiver. See 釘eets (red or table)� chapter in the 天egetables� section in this handbook for how to acquire the label.
Caution  In general, the risk of crop injury from the use of Dual Magnum is less for post-transplant than pretransplant applications, and the risk of crop injury is less with postdirected than from over-the-top post-transplanting applications. Applying Dual Magnum before bed formation may result in crop injury due to the incorporation and/or concentration of Dual Magnum directly near the transplanted crop’s root system. Chinese varieties are more sensitive to injury from Dual Magnum. Preharvest interval is 60 days.
Site of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Chloroacetamide
•  S-metolachlor (Dual Magnum)
horseradish
Rate  0.95 to 1.27 lb ai/A (1.0 to 1.33 pints/A) 
Timing  Prior to crop or horseradish emergence.
Remarks  Use lower rate on coarse soils and higher rates on fine soil. 
Caution  Do not exceed 1.33 pints/A or one application per crop. Harvest horseradish at normal timing.
Site of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Chloroacetamide
•  napropamide (Devrinol 50DF)
broccoli, Brussels sprouts, cabbage, and cauliflower only
Rate  1 to 2 lb ai/A (2 to 4 lb/A), depending on soil texture
Time  For direct-seeded crops, apply to soil surface immediately after planting and sprinkler-irrigate within 24 hr to wet soil 1 to 2 inches deep, or mechanically incorporate not exceeding the seed depth.
Remarks  Selectivity is based on placement above seed or transplant depth. Can be applied with shallow incorporation before transplanting seedlings. Rotational crops listed on the label require deep moldboard plowing. Inhibits root growth.
Caution  Do not plant other crops until 12 mo after application. 
Site of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Acetamide
•  DCPA (Dacthal W75)
excluding rutabagas and turnips
Rate  4.5 to 10.5 lb ai/A (6 to 14 pints/A)
Time  Apply after seeding or transplanting to many Brassica leafy vegetables (see label). Do not apply after transplanting kale, collards, turnip greens, mustard greens, turnips, rutabaga, and radishes. Can be preplant-incorporated for some crops.
Remarks  Can be sprayed directly over transplants of broccoli, cauliflower, cabbage, and Brussels sprouts. Performs erratically west of Cascades. If weeds have emerged, clean-cultivate or weed soil before applying. Results improve with rain or overhead irrigation immediately after application.
Site of action  Group 7: photosystem II inhibitor
Chemical family  Phthalic acid
•  clomazone (Command 3ME)
cabbage only
Rate  0.25 lb ai/A (0.67 pint/A) on seeded cabbage; 0.25 to 0.49 lb ai/A (0.66 to 1.33 pints/A) on transplanted cabbage
Time  Apply as a preemergent soil-applied treatment prior to seeding or transplanting, or after seeding but prior to crop emergence.
Remarks  Before using note crop-rotation restrictions, weeds controlled, and possible injury symptoms for several days after treatment or when applied to sandy soils. The ME formulation is designed to minimize drift and injury to adjacent fields and sites.
Caution  Clomazone may persist in soil up to 16 mo. Consult label on rotational crop guidelines before applying.
Site of action  Group 13: inhibits DOXP synthase
Chemical family  Isoxazolidone
•  oxyfluorfen (Goal 2XL or Galigan 2E)
transplanted broccoli, cabbage, cauliflower
Rate  0.25 to 0.5 lb ai/A (1 to 2 pints/A)
Time  Apply soon after final soil preparation and before transplanting through the treated layer with minimal soil disturbance.
Remarks  Select lower rate for coarse soils with less than 1% organic matter. Leaves that contact treated soil may be temporarily injured. Injury may be severe if transplants are stressed by temperature, disease, fertilizer salts, nematodes, insects, pesticides, and storage conditions or if planting small transplants grown in 1-inch cells. After transplanting, apply at least 0.25 inch overhead moisture. Plant only crops listed on the label within 10 mo after treatment. Grazing crop residue or treated fields is prohibited.
Caution  Acts as a selective contact that disrupts cell membranes.
Site of action  Group 14: inhibits protoporphyrinogen oxidase
Chemical family  Diphenylether
•  oxyfluorfen (GoalTender or Goal 2XL)
horseradish only
Rate  0.5 lb ai/A (1 pint/A GoalTender)
Time  Apply after transplanting roots but before new shoots emerge. Plant tissue exposed at application will be injured.
Remarks  Do not exceed 0.5 lb ai/A per year.
Caution  Acts as a selective contact that disrupts cell membranes.
Site of action  Group 14: inhibits protoporphyrinogen oxidase
Chemical family  Diphenylether
•  sulfentrazone (Spartan 4F)
cabbage for processing
Rate  Refer to product label. Rate depends on soil type and pH. Apply 0.07 lb ai/A (2.25 fl oz/A) on coarse soils with less than 1% organic matter, and 0.375 lb ai/A (12 oz/A) to fine soils with more than 3% OM. Use higher rates when soil pH is less than 7.0 and lower rates when pH is greater than 7.0.
Time  Fall or early spring preplant, preemergence, or preplant-incorporated.
Remarks  Apply in fall or spring up to 30 days before planting cabbage, to suppress weeds. Preplant incorporate to 2 inches. Direct-seeded―apply within 24 hr of planting cabbage. Transplanted―broadcast or band before planting or apply as a banded treatment to row middles within 72 hr after transplanting. Do not exceed 12 oz/A in the 12 mo after the first application.
horseradish
Rate  0.07 lb ai/A (2.25 oz/A) on coarse soil to 0.25 lb ai/A (8 oz/A) on fine soil Rate also depends on OM content. Use higher rates for soils of pH less than 7.0 and lower rates for pH greater than 7.0.
Time  Fall or early spring preplant, preplant-incorporated, or preemergence.
Remarks  Apply in fall or spring to suppress weeds up to 60 days before planting horseradish. Preplant-incorporate to 2 inches. Can apply preemergence to soil surface shortly before planting or within 5 days after planting. Do not exceed 8 oz/A in a 12-mo period that begins with the first application. Do not apply directly to emerged crop or if crop sprouts are near the soil surface. 
Caution  Observe rotational guidelines, which may be as long as 24 mo for some crops.
Site of action  Group 14: inhibits protoporphyrinogen oxidase
Chemical family  Triazinone
•  dimethenamid-P (Outlook)
horseradish only
Rate  0.56 to 0.84 lb ai/A (12 to 18 fl oz/A) on coarse soils and 0.84 to 0.98 lb ai/A (18 to 21 fl oz/A) in medium-texture or fine soils. May be applied in a single application. Do not exceed 21 fl oz/A per season. 
Time  Apply postemergence from the two-leaf to eight-leaf stage of plant development.
Remarks  Postemergence by ground, chemigation, aerial, or impregnated onto dry bulk fertilizer. Application must be to clean-tilled soil or with other herbicides that control emerged weeds. Make chemigation applications only through center pivot, lateral move, solid set, or hand move irrigation systems. Make applications in volume minimums of 0.33 to 0.67 inch of water, using the lower volume on coarser soils and the higher volume on finer soils. Applications in more than 1 inch volume may reduce weed control. Refer to the EPA-approved labels for specific application methods and requirements. Preharvest interval is 40 days.
Caution  To avoid harming endangered plant species, comply with the following mitigation measures where endangered species grow in the counties listed below. Aerial applications must leave a 150-ft untreated buffer between treatment area and endangered plant populations. Ground applications must use low-pressure nozzles that produce only medium to coarse or very coarse droplets and leave a 35-ft untreated buffer between treatment area and endangered plant populations. In Idaho, Kootenai County; in Oregon, Baker, Benton, Josephine, Klamath, Lane, Marion, and Union counties; in Washington, Lincoln County. 
Site of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Chloroacetamide
BRASSICA CROPS―Postemergence
•  sethoxydim (Poast)
except radishes, rutabaga, and turnips
Rate  0.19 to 0.28 lb ai/A (1 to 1.5 pints/A)
Time  Apply at optimum growth stage listed on the label.
Remarks  Identify susceptible grasses and add 2 pints/A nonphytotoxic crop oil concentrate to improve leaf absorption. Control often is erratic on grasses stunted or stressed from drought, high temperatures, or low fertility. Resistant grasses include annual bluegrass and all fine fescues, but quackgrass can be suppressed.
Caution  Preharvest interval is 30 days (14 days for mustard greens). Do not exceed 3 pints/A per season. Inhibits fatty acid production, cell membranes, and new growth.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione 
•  clethodim (Select 2EC or others)
Rate  0.094 to 0.125 lb ai/A (6 to 8 fl oz/A Select), depending on whether annual or perennial species dominate.
Time  Apply to actively growing grass weeds, including annual bluegrass,  at growth stages on label.
Remarks  Read label carefully for adjuvant instructions, typically 1% crop oil concentrate without nitrogen solution. Note effects of rain within 1 hr, application of other pesticides, and cultivation.
Caution  Consult labels for maximum rates per application and season. Preharvest interval is 14 days for leafy Brassica greens, 30 days for head or stem Brassica vegetables.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione 
•  clopyralid (Clopyr-AG)
except radish and horseradish
Rate  Apply 0.093 to 0.188 lb ae/A (0.25 to 0.5 pint/A) with ground equipment in 10 to 40 gal/A total spray volume.
Timing  Apply to wild buckwheat at the one- to three-leaf stage of growth, before vining begins. Apply to common ragweed and sweet clover from weed emergence up to the five-leaf stage of growth. To suppress sowthistle, apply from rosette up to bud stage.   
Remarks Controls wild buckwheat, sweet clover, prickly lettuce, common ragweed, and galinsoga. Suppresses sowthistle and nightshade.  Preharvest interval is 30 days. Make one broadcast application per crop per year. Experience is lacking with this product on many of these crops in the PNW.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine

breakhere  
Carrots, Celery, and Parsnips
Ed Peachey
Revised November 24, 2008
CARROTS, CELERY, AND PARSNIPS―Site Preparation, Stale Seedbeds, and Selective Postemergence Applications
See “Site Preparation,” “Registered Uses for Glyphosate,” and “Registered Uses of Aim Herbicide in Food Crops” at the beginning of the Vegetables section in this handbook.
CARROTS, CELERY, AND PARSNIPS―Preplant Incorporated
•  trifluralin (Treflan 4L)
carrots and celery only
Rate  0.5 to 1 lb ai/A (1 to 2 pints/A)
Time  Apply from 3 wk to immediately before planting and incorporate 2 to 3 inches deep within 24 hr by cross-disking or using a power take-off rotary tiller.
Remarks  Spray only once and avoid overlaps.
Caution  Consult label for restrictions on planting sensitive crops within 12 mo. (Inhibits mitosis, primarily in shoots.)
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
•  bensulide (Prefar 4-E)
celery only
Rate  5 to 6 lb ai/A (5 to 6 quarts/A)
Time  Preplant-incorporate to the optimum depth of 1 inch; deeper than 2 inches reduces weed control.
Remarks  For furrow irrigation, thoroughly saturate bed top. Sometimes the first flush of weeds must be controlled with cultivation before herbicide begins to control grass. Replant is 120 days for all crops not listed on the label.
Site of action  Group 8: lipid synthesis inhibitor but not an ACCase inhibitor
Chemical family  Organophosphorus
CARROTS, CELERY, AND PARSNIPS―Preemergence
•  linuron (Lorox DF, for carrots, celery, and parsnips; or Linex 4L, for parsnips only)
Rate  Carrots and celery 0.5 to 1 lb ai/A (1 to 2 lb/A Lorox); parsnips 0.75 to 1.5 lb ai/A (1.5 to 3 lb/A Lorox)
Time  Apply before crop and weeds emerge.
Remarks  Use lower rates on light soils, but do not use on extremely sandy soils or soils with less than 1% organic matter. Plant seed at least 0.5 inch deep and apply preemergence only once per season. Carrots and celery may be followed by postemergence applications, but do not exceed 3 lb/A per season.
Caution  Consult label for planting sensitive crops within 4 mo. 
Site of action  Group 7: photosystem II inhibitor
Chemical family  Substituted urea
•  S-metolachlor (Dual Magnum)
carrots and parsnips only; Oregon only
Rate  0.64 lb ai/A (0.67 pint/A)
Timing  Make a single broadcast application of Dual Magnum to soil surface after planting but before weeds or crop emerge. For effective weed control, soil must be clean-tilled.
Remarks  Special local needs indemnified label (OR-060012). This label is available only through the Syngenta Farm Assist website (www.farmassist.com), and may be accessed as described in the 典able Beet� section above.
Make uniform applications in at least 15 gal/A of water. A band application also may be used. Irrigate after application to activate the herbicide if rain is not expected. If the crop is irrigated, use 0.5 inch of water shortly after planting to incorporate the herbicide. Excessive irrigation before the crop emerges may increase the risk of crop injury.
Caution  Do not mechanically incorporate Dual Magnum. Do not use Dual Magnum if the planting operation creates a furrow or trough over the seed row into which rain or irrigation water will collect and thus concentrate the herbicide over the row. Do not use on coarse soils with less than 1.5% organic matter or on any soil with greater than 10% organic matter. Do not exceed a total of 0.67 pint/A of Dual Magnum in any single application nor in total applications per crop.
Site  of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Chloroacetamide
•  ethofumesate (Nortron SC, Ethotron)
carrots only, in Oregon and Washington only
Rate  Coarse soils―1.5 lb ai/A (48 fl oz/A); medium-texture and fine soils―2 lb ai/A (64 fl oz/A)
Time  Apply after planting and activate with at least 0.5 inch water. If sufficient water will not be available to incorporate the herbicide, incorporate it mechanically before or at planting.
Remarks  Do not use smaller than 50 mesh screen and avoid overlaps, which may increase risk of crop injury.
Caution  May cause temporary leaf fusion, distortion, and stunting when used as label directs and under normal growing conditions. If crop is lost due to unfavorable growth conditions after application, do not plant anything except sugar beets, table beets, carrots, onions, garlic, shallots, or ryegrass.
Site of action  Group 16: unknown
Chemical family  Benzofuran
•  pendimethalin (Prowl H2O) 
carrots only; supplemental label
Rate  0.95 lb ai/A (2 pints/A)
Time  Postplant, before crop and weeds emerge (within 2 days of planting), and at layby.
Remarks  May be applied by air, ground, or chemigation postplant but only by ground equipment at layby. Do not apply over the tops of carrots, or crop may be injured.
Caution  Note the crop-injury disclaimer on this label. BASF recommends testing this herbicide on a small part of the target crop to determine whether damage is likely. Do not exceed 2 pints/A per season. Preharvest interval is 60 days.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
CARROTS, CELERY, AND PARSNIPS―Postemergence
•  linuron (Lorox DF)
carrots and transplanted celery only
Rate  0.75 to 1.5 lb ai/A (1.5 to 3 lb/A product)
Time  Apply postemergence when carrots are 3 inches tall or when celery is established after transplanting but is less than 8 inches tall. 
Remarks  Treat grass weeds less than 2 inches tall and broadleaf weeds less than 6 inches tall. Do not exceed 40 psi spray pressure. Weed control may be poor if daytime high is below 50°F. Crop may be injured if herbicide is mixed with surfactants, nitrogen, or fertilizer solution, or if temperatures exceed 85°F. Repeat applications on carrots may be made but do not exceed a total of 3 lb/A product.
Caution  Carrot varieties differ in their resistance; determine tolerance to linuron before applying, to prevent possible crop injury. Do not apply on sand, loamy sands, gravelly soils, or soils with less than 1% organic matter. Do not apply by air. Consult label for planting rotation crops within 12 mo. Preharvest interval is 14 days for carrots, 67 days for celery. 
Site of action  Group 7: photosystem II inhibitor
Chemical family  Substituted urea
•  metribuzin (Sencor)
carrots only
Rate  0.25 lb ai/A (0.33 lb/A of Sencor DF or 0.5 pint/A of Sencor 4F)
Time  Apply after carrots form five to six true leaves but before weeds are 1 inch high or wide.
Remarks  Earlier applications will result in excessive crop injury.
Caution  If needed, repeat application after at least 3 wk but do not exceed 0.5 lb ai/A per year. Preharvest interval is 60 days. Do not apply within 3 days of any other chemical or within 3 days after periods of cool, wet, or cloudy weather or on very hot days. Leaf tissue may be temporarily chlorotic or burned. For carrots with unknown tolerance, treat only a small area to determine crop safety. 
Site of action  Group 5: photosystem II inhibitor
Chemical family  Triazinone
•  ethofumesate (Nortron SC)
carrots only, in Oregon and Washington only
Rate  2 lb ai/A (64 oz/A) to carrots with two to four true leaves
Time  Apply after planting and activate with at least 0.5 inch water.
Remarks  Do not use smaller than 50 mesh screen and avoid overlaps, which may increase risk of crop injury. Rain or irrigation within 6 hr after irrigation may reduce weed control. Do not cultivate more than 2 inches deep.
Caution  May cause temporary leaf fusion, distortion, and stunting when used according to label directions and under normal growing conditions. Nortron may cause stand loss if the crop is under stress. Apply in evening if air was warmer than 80°F during the day. If crop is lost due to unfavorable growth conditions after application, do not plant anything except sugar beets, table beets, carrots, onions, garlic, shallots, or ryegrass.
Site of action  Group 16: unknown 
Chemical family  Benzofuran
•  fluazifop (Fusilade DX)
carrots only
Rate  Refer to specific grassy weeds on label
Time  Apply to actively growing grasses as a directed spray with 1% crop oil or 0.25% nonionic surfactant. Results often are erratic on grasses stressed from lack of vigor, drought, high temperature, or low fertility. More mature grasses and quackgrass can be controlled but may require two applications. Annual bluegrass and all fine fescues resist treatment.
Remarks  Identify grasses, and adjust rates, depending on susceptibility and stage of weed growth according to label instructions. Inhibits fatty acid production, cell membranes, and new growth.
Caution Preharvest interval is 45 days. Do not exceed 48 oz/A per year. Grazing is prohibited.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Aryloxyphenoxy propionate
•  sethoxydim (Poast)
carrots and celery only
Rate  0.5 lb ai/A (2.5 pints/A) for carrots; 0.28 lb ai/A (1.5 pints/A) for celery
Time  Apply at optimum growth stage listed on the label.
Remarks  Identify susceptible grasses, and add 2 pints/A nonphytotoxic crop oil concentrate to improve leaf absorption. Results often are erratic on grasses stressed from lack of vigor, drought, high temperature, or low fertility. Resistant grasses include annual bluegrass and all fine fescues; quackgrass can be suppressed. Inhibits fatty acid production, cell membranes, and new growth.
Caution Preharvest interval is 30 days. Do not exceed 5 pints/A for carrots or 3 pints/A for celery per season.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione
•  clethodim (Select 2EC; Prism―Oregon only; or Select Max)
Rate  0.094 to 0.125 lb ai/A (6 to 8 fl oz/A Select 2EC). Consult label for rate required to control different grasses.
Time  Apply to actively growing grasses at recommended weed heights.
Remarks  Add crop oil concentrate as described on label. Do not exceed 8 fl oz/A per season.
Caution  Consult labels for maximum rates per application and season. Preharvest interval is 30 days. 
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione

breakhere  Corn (Sweet) 
Ed Peachey
Revised November 24, 2008
CORN, SWEET―Site Preparation,  Stale Seedbeds, and Selective Postemergence Applications
See ‘Site Preparation’, ‘Registered Uses for Glyphosate’, and ‘Registered Uses of Aim Herbicide in Food Crops’ at the beginning of the Vegetables section in this handbook.

CORN, SWEET―Preplant Incorporated and Preemergence Surface
•  EPTC + safener (Eradicane) 
not for seed stock
Rate  3.14 to 6.14 lb ai/A
Time  Apply preplant to soil dry enough for thorough mixing and incorporate immediately by disking in two directions or rototilling into top 2 to 3 inches of soil.
Remarks  Avoid planting corn seed more than 2 inches deep. Suppresses growth of yellow nutsedge and wild proso millet when applied with Outlook (dimethenamid-P). Inhibits shoot growth. 
Caution  Consult label regarding other tank-mixes. Crop may be injured if growing under adverse conditions such as pest attacks or extended cold and wet or hot and dry periods.
Site of action  Group 8: lipid synthesis inhibitor but not an ACCase inhibitor
Chemical family  Thiocarbamate
•  butylate  + safener (Sutan +)
not for seed stock
Rate  4 to 6 lb ai/A (4.75 to 7.33 pints/A) depending on target weed species
Time  Preplant incorporated―Apply to soil dry enough for thorough mixing and incorporate immediately by disking in two directions or rototilling into top 2 to 3 inches of soil.
Preemergence surface―In semiarid regions of Idaho and eastern Oregon and Washington, may be applied immediately after planting to dry soil surface (at least 0.5 inch deep) that remains free of dew and incidental moisture. Incorporate with overhead irrigation within 36 hours.
Remarks  Avoid planting corn seed more than 2 inches deep. Suppresses growth of yellow nutsedge and other perennial grasses. Inhibits shoot growth.
Caution  Consult label regarding other tank-mixes. Crop may be injured if growing under adverse conditions such as extended cold/wet or hot/dry periods or pest attacks.
Site of action  Group 8: lipid synthesis inhibitor but not an ACCase inhibitor
Chemical family  Thiocarbamate
•  dimethenamid-P (Outlook)
Rate  0.56 to 0.98 lb ai/A (12 to 21 fl oz/A)
Time  Apply preplant incorporated, preplant surface, or preemergence surface.
Remarks  Consult label for application rate in relation to soil type. Use lower rates on coarse soils with low organic matter or low cation exchange capacity. Control is best if incorporated into soil by overhead moisture or a light mechanical tillage (1 to 2 inches deep) before weed seedlings emerge. May be tank-mixed with other herbicides to improve weed control. Control of wild proso millet can be enhanced if Outlook is applied preemergence after preplant-incorporating Eradicane or Dual Magnum. 
Caution  Apply to irrigation systems as described on the label. Delayed emergence or leaf wrapping of sweet corn may occur if conditions are extreme (heavy rain and extended periods of water-saturated soil and/or cool weather) during germination and emergence, particularly for preplant-incorporated applications followed by cool, wet weather. Do not apply on sweet corn grown for seed.
Site of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Chloroacetamide
•  S-metolachlor (Dual Magnum or Dual II Magnum with corn safener) or
•  metolachlor (Parallel)
Rate  Consult labels to adjust rates for soil types and organic matter content. 
Time  Apply preplant incorporated, preemergence, or early postemergence before weeds germinate or yellow nutsedge emerges.
Remarks  Activate with shallow incorporation or overhead moisture. Dual II has corn safener.
Caution  Consult label for specific rates, depending on soil texture and especially organic matter, or for restrictions on planting sensitive crops within 4 to 5 mo. Inhibits roots and shoots.
Site of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Chloroacetamide
•  alachlor (Micro-Tech or several premixes with atrazine)
Rate  2 to 3.5 lb ai/A (2 to 3.5 quarts/A) depending on application timing and soil type
Time  Preplant incorporated―apply immediately before planting, and incorporate mechanically in top 1 to 2 inches of soil for furrow-irrigated corn. Preemergence surface―apply after planting and incorporate by cross-harrowing with a spike-tooth harrow; or activate with overhead irrigation.
Remarks  Can apply through a center-pivot irrigation system. See label for specific rates, depending on soil texture, organic matter, and possible use of tank-mixes or other herbicide combinations. Controls atrazine-resistant redroot pigweed, nightshade, and purslane. Inhibits roots and shoots.
Caution  A restricted-use herbicide due to ground and surface water contamination potential.
Site of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Chloroacetamide
•  mesotrione (Callisto)
Rate  0.188 to 0.24 ai/A (6 to 7.7 fl oz/A)
Time  Apply preemergence surface after planting.
Remarks  Good control of some broadleaves. Tank-mix with atrazine to improve weed control.
Caution  Some sweet corn varieties are more sensitive than others. Rotational interval is 18 mo for peas, snap beans, cucurbits, beets, and many other crops. Crop yield may be reduced if applied to corn treated with the insecticides Counter or Lorsban.
Site of action  Group 28: inhibits 4-hydroxyphenylpyruvatedioxygenase (4-HPPD)
Chemical family  Triketone
•  pendimethalin (Prowl 3.3EC or Prowl H2O)
Rate  0.74 to 1.98 lb ai/A (1.8 to 4.8 pints/A Prowl 3.3, or 2 to 4 pints/A Prowl H2O) depending on soil texture and organic matter content.
Time  Apply preemergence only; do not preplant-incorporate. Apply over a uniform seedbed with corn seed planted 1.5 inches deep to ensure selectivity.
Remarks  Note rates listed on label for different soil types and organic-matter contents. 
Caution  May cause lodging of sweet corn. Planting deeply may help to reduce lodging. Do not incorporate. Use only shallow cultivation to reduce soil mixing at or near seed. Do not apply to reduced-till or no-till corn.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
•  atrazine (several brands)
Rate  Consult label for yearly changes.
Time  Apply preplant or preemergence by selecting rates depending on soil type listed on label.
Remarks  Activate with overhead irrigation in 7 days or incorporate mechanically in top 2 inches of soil for rill-irrigated fields east of the Cascades. Control of barnyardgrass and yellow foxtail is poor if the soil surface remains dry or if these grasses grow beyond the two-leaf stage. Do not plant crops other than corn during the season of treatment. Other crops can be planted the next year west of the Cascades if treated before June 10 with 2 lb/A or less; east of the Cascades, use other herbicides when planting corn the next year.
Caution  A restricted-use herbicide. Do not graze treated area or feed treated forage to livestock for 45 days after application. Do not exceed 2.5 lb ai/A per year. After harvest, plow and thoroughly mix the soil to reduce possible injury. Inhibits photosynthesis.
Site of action  Group 5: photosystem II inhibitor
Chemical family  Triazine
•  simazine (Princep 4l, Simazine 4L, and others)
Rate  1.6 to 4 lb ai/A (1.6 to 4 quarts/A, depending on product) 
Time  Preemergence, apply before weeds and corn emerge
Remarks  Maximum rate on highly erodible soils is 1.6 quarts/A if less than 30% of the soil is covered with plant residues. Preharvest and pregrazing interval is 45 days. Can be preplant-incorporated.
Caution  A restricted-use herbicide in Washington. Do not plant crops other than corn for 1 yr. Do not graze treated areas. Do not exceed 2.5 quarts/A per year. After harvest, plow and thoroughly mix the soil to reduce possible injury. Inhibits photosynthesis.
Site of action  Group 5: photosystem II inhibitor
Chemical family  Triazine
•  acetochlor (Harness, Surpass or Cadence)
Rate  0.8 to 3 lb ai/A. Consult appropriate label for rates.
Time  Apply preplant or preemergence.
Remarks  Use lower rates on coarse soils with low organic matter. May be surface-applied or incorporated into top 1 to 2 inches of soil. If rain or 0.25 to 0.75 inch of overhead irrigation does not occur within 7 days of a surface application, shallowly incorporate herbicide with a rotary hoe or similar device. May tank-mix with several other herbicides to broaden activity.
Caution. Improper incorporation methods or poor soil preparation may reduce weed control. Consult label for crop rotation restrictions.
Site of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Chloroacetamide

breakhere  CORN, SWEET―Postemergence Soil- applied
•  dimethenamid-P (Outlook)
Rate  0.56 to 0.98 lb ai/A (12 to 21 fl oz /A)
Time  Early postemergence on corn up to 12 inches tall.
Remarks  Consult label for application rate in relation to soil type. Use lower rates on coarse soils with low organic matter or low cation exchange capacity. May be tank-mixed with other herbicides to provide burndown with residual control.
Caution  Consult label for instructions on applications made through some irrigation systems. Regional experience indicates that corn may be injured by postemergence applications made during very hot weather. Do not apply on sweet corn grown for seed.
Site of action Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Chloroacetamide
•  S-metolachlor (Dual Magnum or Dual II Magnum with corn safener) or
•  metolachlor (Parallel)
Rate  Consult labels to adjust rates for soil types and organic matter content.
Time  Apply preplant incorporated, preemergence, or early postemergence before weeds germinate or yellow nutsedge emerges.
Remarks  Activate with shallow incorporation or overhead moisture. Dual II has corn safener.
Caution  Consult label for specific rates, depending on soil texture and especially organic matter, or for restrictions on planting sensitive crops within 4 to 5 mo. Inhibits roots and shoots.
Site of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Chloroacetamide
•  pendimethalin (Prowl 3.3EC or Prowl H2O)
Rate  0.74 to 1.98 lb ai/A (1.8 to 4.8 pints/A Prowl 3.3, or 2 to 4 pints/A Prowl H2O), depending on soil texture and organic matter content
Time  Apply to emerged corn until 20 to 24 inches tall or at V8 growth stage, whichever is more restrictive.
Remarks  Does not control emerged weeds. Note rates listed on label for different soil types and organic-matter content. Tank-mix with other postemergent herbicides to control emerged weeds. Use drop nozzles if the corn canopy intercepts the spray and prevents it from uniformly reaching the soil.
Caution  May cause lodging of sweet corn. Planting deeply may help to reduce lodging. Do not incorporate. Use only shallow cultivation to reduce soil mixing at or near seed.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
CORN, SWEET―Postemergence Foliar-applied
•  topramezone (Impact)
Rate  0.0164 to 0.218 lb ai/A (0.75 to 1 oz/A)
Time  Apply postemergence to actively growing weeds 3 to 8 inches tall.
Remarks  Controls wild proso millet, several other annual grasses, and many annual broadleaf weeds. A supplemental label for Oregon, Washington, and Idaho allows for up to 1 oz/A in single or sequential applications. Tank-mixes with residual herbicides such as S-metolachlor and dimethenamid-P will improve long-term control of early applications. See label for optimum treatment time for weeds of different sizes. Add methylated seed oil or crop oil concentrate at 1 to 1.5% v/v and UAN or ammonium phosphate at 1.2 to 1.5% v/v to the spray solution. Spray-grade ammonium sulfate at 8.5 lb/100 gal of water may be substituted for the nitrogen fertilizers. For best performance, tank-mix topramezone with 0.25 to 1 lb ai/A of atrazine. Topramezone may be used sequentially or in combination with all soil- or foliar-applied insecticides registered for use in corn. Preharvest interval is 45 days.
Caution  Apply only once per growing season. See label (and supplemental label) for Oregon, Washington, and Idaho rotational crop restrictions. Has not been tested on all sweet corn lines for tolerance.
Site of action Group 28: inhibits 4-hydroxyphenylpyruvatedioxygenase (4-HPPD)
Chemical family  Triketone
•  tembotrione  (Laudis)
Rate  0.082 lb ai/A (3oz product/A)
Time  Apply to actively growing weeds from emergence to the V8 stage of growth or sweet corn up to the V7 stage of growth. 
Remarks  One application per season on sweet corn. Consult label for maximum weed size. Use methylated seed oil (MSO) at 1% v/v plus ammonium nitrogen fertilizer (UAN) at 1.5 quarts/A or 1.5 lb/A spray-grade ammonium sulfate (AMS) when tembotrione is used alone, or when a specific adjuvant is not specified on the label. Tank-mixes with residual herbicides such as S-metolachlor (Dual Magnum) and dimethenamid-P (Outlook) will improve long-term control. Adding atrazine at 1 pint/A significantly broadens the spectrum of control.
Caution  Not all hybrids of corn have been tested for herbicide tolerance. Weed control may be reduced if applied to stressed weeds or weeds covered by dust or heavy dew. Do not graze livestock or harvest for forage within 45 days after application. Note crop rotation restrictions on label.
Site of action  Group 27: inhibits 4-hydroxyphenylpyruvatedioxygenase (4-HPPD)
Chemical family  Triketone
•  mesotrione (Callisto)
Rate  0.094 lb ai/A (3 oz/A)
Time  Apply postemergence to corn less than 5 inches tall. 
Remarks  Good control of some broadleaves, with suppression of wild proso millet. 
Caution  Some sweet corn varieties are more sensitive than others. Rotation interval is 18 mo for peas, snap beans, cucurbits, beets, and many other crops. Crop yield may be reduced if applied to corn treated with the insecticides Counter or Lorsban. See label for adjuvant restrictions for sweet corn, which recommends nonionic surfactant rather than crop oil concentrate, particularly under lush growing conditions. Do not add UAN or AMS.
Site of action  Group 28: inhibits 4-hydroxyphenylpyruvatedioxygenase (4-HPPD)
Chemical family  Triketone
•  carfentrazone (Aim EC)
Rate  0.008 to 0.016 lb ai/A (0.5 to 1 fl oz/A Aim EC)
Time  Apply to actively growing weeds up to 4 inches tall or 3 inches across. Apply to corn from before planting up to the 14th collar growth stage and when weeds are small. Use directed applications if corn is larger than the V-8 stage.
Remarks  Adjust nozzles to minimize herbicide application directly over row or in whorl of corn plant. Acts as a contact. Fields can be planted to labeled crops at any time and rotated to any other crop 12 mo after application (see label). Good spray coverage is essential. 
Caution  Avoid applying to corn with collars filled with water. Use only a nonionic surfactant on sweet corn. Avoid any chance of spray drift to nontarget sites. User assumes all responsibility for crop loss or damage of sweet corn varieties and inbred lines for seed production. Overlapping applications can injure crop. Tank-mixtures of carfentrazone with emulsifiable concentrate (EC) formulations of other herbicides, fungicides, or insecticides, or with crop oil concentrate, methylated seed oil, or silicone-based adjuvants may increase crop injury. Adding nitrogen or ammonium sulfate with nonionic surfactant may increase leaf injury. Do not exceed 0.031 lb ai/A (2 fl oz/A Aim EC) per season.
Site of action  Group 14: inhibits protoporphyrinogen oxidase
Chemical family  Triazinone
•  bentazon (Basagran)
Rate  0.5 to 1 lb ai/A (1 to 2 pints/A)
Time  Apply to small annual broadleaf weeds; see label for maximum weed size.
Remarks  Use higher rate with crop oil concentrate applied twice, 7 to 10 days apart, for Canada thistle and yellow nutsedge. Irrigate before application to ensure vigorous weed growth. Control is poor if day and night are below 75° and 55°F, respectively. Use at least 5 gal/A water and at least 40 psi to ensure thorough coverage of weed foliage. Leaves may be speckled temporarily, but plants continue growth without further symptoms within 10 days.
Caution  Do not apply to corn growing under stress conditions. Do not mix with other pesticides. Do not exceed 2 lb ai/A per season. Inhibits photosynthesis.
Site of action  Group 6: photosystem II inhibitor
Chemical family  Benzothiadiazole
•  bentazon + atrazine (Laddok)  
western Oregon and Washington only
Rate  Consult label
Time  Apply early postemergence when weeds are small and actively growing. Adjust rates to weed size.
Remarks  Controls broadleaf weeds.
Caution  Atrazine is a restricted-use herbicide. Note limitations for atrazine and bentazon above. 
Site of action  (bentazon) Group 6: photosystem II inhibitor; (atrazine) Group 5: photosystem II inhibitor
Chemical family  (bentazon) benzothiadiazole; (atrazine) triazine
•  atrazine + crop oil
Rate  Consult label.
Time  Apply postemergence before grass weeds exceed 1.5 inches and broadleaf weeds 4 to 6 inches but before corn is 12 inches tall.
Remarks  Use lower water carrier volumes to improve activity. Do not exceed 1 to 1.5 lb ai/A when wheat is expected to follow in the rotation. Consult label for replanting sensitive crops within 12 to 24 mo.
Caution  A restricted-use herbicide. Do not apply more than once per season, except as suggested to suppress yellow nutsedge and Canada thistle. Reduce potential soil residue by keeping applications under 2 lb/A, or select other herbicides. Inhibits photosynthesis.
Site of action  Group 5: photosystem II inhibitor
 •  2,4-D amine (3.8 lb ae/A)
Rate  0.24 to 0.71 lb ae/A (0.5 to 1.5 pints/A)
Time  Apply after corn is tall enough to use drop nozzles between rows.
Remarks  To avoid drift injury, use the same precautions in spraying 2,4-D as for winter cereals. Avoid contact with corn foliage to reduce brittle stalks and whorl distortion that prevents tassel emergence. Mimics natural plant hormones.
Caution  Do not apply from tasseling to dough stage of corn. Crop injury is more likely if corn is growing rapidly under high temperature and high soil moisture. 
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  nicosulfuron (Accent, Accent Q)
Rate  0.24 to 1.0 oz ai/A (0.33 to 1.33 oz/A)
Time  Apply to actively growing weeds, either broadcast before corn is at fourth-collar stage (see label for definition) or with drop nozzles according to label instructions.
Remarks  See label for details, application restrictions, and ways to minimize potential crop injury. Applying 0.66 oz/A generally is sufficient to control wild proso millet without undue risk of injuring sweet corn. In recent research, tank-mixes of Outlook and/or Lorsban or other insecticides caused severe injury. Adjuvants improve uptake into leaves. Sweet corn variety tolerance to both Accent and Callisto herbicides is online at http://www.rec.udel.edu/weed_sci/WeedFacts/SweetCorn%20Trial%20Summary.htm. Accent Q includes the safener isoxadifen.
Caution  Avoid repeat applications in the same field, to minimize selection for resistant weed biotypes. Do not apply as a tank-mix with Basagran (bentazon), as serious injury will result. Do not apply when the difference between the daytime high and the nighttime low is expected to be 35°F or greater. Note especially precautions about types and timings of insecticide applications and environmental conditions that stress corn growth or reduce corn metabolism of nicosulfuron. Do not graze livestock or feed any treated component within 30 days of application. Read and understand this label thoroughly before treating sweet corn.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  foramsulfuron (Option)
Rate  0.033 to 0.038 lb ai/A (1.5 to 1.75 oz/A product)
Time  Apply postemergence up to the V5 stage of development or 16 inches tall. Drop nozzles must be used when corn is beyond the V5 stage or 16 to 36 inches tall.
Remarks  Always use a methylated or ethylated seed oil at 1.5 pints/A, plus UAN (28-0-0 or 32-0-0) at 2 quarts/A. Apply in 10 to 20 gal/A water. Target application timing to annual grasses 1 to 3 inches tall. Option controls nightshades better than Accent.
Caution  Do not rotate to other crops for 60 days after applying. Do not combine with crop oil concentrate or nonionic surfactant. Foramsulfuron, like other sulfonylurea herbicides, may temporarily stunt or yellow corn. Follow seed company recommendation charts for hybrid sensitivity to sulfonylurea herbicides or ALS inhibitors. Do not apply to corn that shows injury from previous applications of other herbicides. Do not apply in the same season with the insecticides Counter 15 G, Counter 20 G, Dyfonate, or Thimet. Do not make foliar applications of an organophosphate insecticide within 7 days of application, or corn may be injured. Do not apply more than twice per season.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  clopyralid (Stinger)
Rate  0.123 to 0.25 lb ae/A (0.33 to 0.66 pint/A product) 
Time  Apply to actively growing broadleaf weeds after corn emerges up to 24 inches tall. For Canada thistle, apply after most basal leaves emerge but before bud stage.
Remarks  For best results on Canada thistle, use at least 0.5 pint/A product. Do not cultivate before treatment; wait 2 wk after treatment before cultivation. Re-treat as necessary but do not exceed 0.66 pint/A product per calendar year. Preharvest interval is 30 days for ears and forage, 60 days for stover. Make one to two broadcast applications per crop per year, not to exceed a total of 0.66 pint/A. Retreatment interval is 21 days
Caution  Do not graze treated areas or harvest corn for feed within 40 days of treatment. Wheat, barley, canola, brassica crops (including those grown for seed), garden beets, sugar beets, oats, grasses, field corn, spinach, or turnips may be planted any time after treatment.
Asparagus, grain sorghum, mint, onion, and strawberries can be planted 12 mo after application.
Alfalfa, dry bean, soybeans, and sunflowers can be planted 1 mo after application if rain (not including irrigation) is greater than 18 inches, or after 18 mo if rainfall is less than 18 inches.
Do not plant broadleaf crops grown for seed (excluding Brassica seed crops), carrot, celery, lentils, lettuce, melons, peas, potatoes, safflower, or tomato for 18 mo after applying clopyralid.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  paraquat (Gramoxone Max or Firestorm)
Rate  Consult labels.
Time  Apply postemergence as a directed spray when corn is at least 10 inches tall with nozzles arranged to spray no higher than the lower 3 inches of corn stalks. Add a nonionic surfactant or crop oil concentrate according to label specifications, taking care to avoid anionic formulations that react in the tank to form insoluble precipitates.
Remarks  Acts as contact; absorbs energy produced by photosynthesis, forming peroxides that disrupt living cells.
Caution  A restricted-use pesticide. Do not ingest or inhale spray mist. Wear protective face shields, respirators, and clothing. 
Site of action  Group 22: photosystem I electron diversion.
Chemical family  Bipyridilium
• clopyralid (Stinger)
Rate  Apply 0.124 to 0.25 lb ae/A (0.33 to 0.66 pint/A of Stinger) uniformly with ground equipment as a broadcast or directed spray in 10 to 20 gal/A total spray volume.
Time  Any time after sweet corn emerges until it is more than 18 inches tall.
Remarks  To control Canada thistle, apply when most thistle plants have emerged and thistles are at least 6 to 8 inches wide or tall, but before bud stage. To control Jerusalem artichoke, common cocklebur, jimsonweed, ragweed (common and giant), annual sowthistle, and sunflower, apply Stinger from weed emergence up to the five-leaf growth stage. Use a higher rate listed for heavy infestations or when greater residual control is desired.      
Caution  Preharvest interval is 30 days for ears and forage, 60 days for stover. Make one to two broadcast applications per crop per year, not to exceed a total of 0.66 pint/A. Retreatment interval is 21 days.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  halosulfuron-methyl (Sandea)
Rate  0.5 to 0.75 oz ai/A (0.66 to 1 oz/A)
Time  Apply postemergence from spike through layby stage. 
Remarks  Sandea is not recommended for use on ‘Golden Jubilee.’ Avoid concentrating spray toward leaf middles. Maximum of 0.75 oz ai/A per application on sweet corn and popcorn. Controls only susceptible broadleaf weeds and nutsedge. Nightshades are not controlled. Always add a nonionic surfactant if not tank-mixed with other herbicides. Apply only with ground equipment. May apply up to two times during growing season.
Caution  Not all varieties have been tested for sensitivity to this herbicide. Before using, consider crop rotation plans. Do not replant or rotate to wheat within 2 mo.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  fluthiacet-methyl (Cadet)
Idaho only
Rate  0.003 to 0.009 lb ai/A (0.4 to 0.9 fl oz Cadet/A)
Time  Apply to corn from two leaf (two leaf collars) to when corn is 48 inches tall or before tasseling, whichever comes first. See label for maximum growth stage and weeds controlled.
Remarks  See label for maximum weed size. Spray adjuvants required for optimum weed control. See label for adjuvant recommendations. Thorough coverage is essential for control of susceptible broadleaf weeds.
Caution  Do not exceed 0.009 lb ai/A (1.25 fl oz/A Cadet) per season.
Site of action  Group 14: protoporphyrinogen oxidase inhibitor 
Chemical family Triazinone
•  fluroxypyr (Starane) 
Rate  0.125 lb ae/A (0.66 pint/A product)
Time  Apply broadcast to actively growing broadleaf weeds before they are 8 inches tall, and up to and including four fully exposed leaf collars (V4 growth stage). After the V5 or V4 stages, apply as a directed spray with drop nozzles.
Remarks  Primarily to control volunteer potatoes in sweet corn, but acts on a number of broadleaf weeds.
Caution  Not all sweet corn varieties have been screened for tolerance to fluroxypyr, and varieties may differ in their tolerance. Do not allow grazing. Preharvest interval is 47 days for foraging treated field corn, 31 days for sweet corn ears. Do not add a spray adjuvant when applying fluroxypyr alone on sweet corn.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
breakhere CORN, SWEET―Quackgrass and Other Perennial Grass Control
•  glyphosate
See the Vegetable Site Preparation section in this handbook.
•  glyphosate (numerous product names)
Rate  Consult labels.
Time  Spot-treat vigorously growing quackgrass 6 to 8 inches tall by eliminating both the weed and crop within the treated area.
Remarks  Spray before corn silks to avoid residues in the harvested crop.  Inhibits production of three amino acids and protein synthesis.
Caution  Do not treat more than 10% of the acreage.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  EPTC or
•  butylate
See “Corn, Preplant-incorporated” section in this chapter. Suppresses perennial grasses only.
•  atrazine
Rate  Consult label
Time  Apply in fall or, preferably, spring either as a single application at higher rates 1 to 3 wk before plowing to actively growing quackgrass or as a split treatment, first before plowing and second before, during, or after planting, before weeds are 1.5 inches tall.
Remarks  Adding a nonionic adjuvant enhances control. Control of wild proso millet is poor. See label for planting sensitive crops within 12 to 24 mo, depending on time of application and total applied. Select other herbicides with reduced soil persistence to reduce carryover.
Caution  A restricted-use herbicide. Do not graze treated area or feed treated foliage to livestock for 45 days after treatment. 
Site of action  Group 5: photosystem II inhibitor
Chemical family  Triazine
•  sethoxydim (Poast)
Rate  Consult label; maximum rate is 0.28 lb ai/A (1.5 pints/A) with a maximum of 0.56 lb ai/A (3 pints/A) per year).
Time  Maximum height for quackgrass and wild proso millet control is 8 and 10 inches, respectively.
Remarks  For use in Poast-protected sweet corn varieties such as Rogers GH 2042, GH 6333, and GH 6631. May be applied over the top. A second application is allowed 10 days after the first. Identify susceptible grasses and add 2 pints/A nonphytotoxic crop oil concentrate to improve leaf absorption. Control often is erratic on grasses stunted or stressed from drought, high temperatures, or low fertility. Resistant grasses include annual bluegrass and all fine fescues; quackgrass can be suppressed. Grass control may be reduced if applied with bentazon. Inhibits fatty acid production, cell membranes, and new growth.
Caution  Do not apply to corn hybrids that are not tolerant to Poast. Do not exceed 3 pints/A per year. Preharvest interval is 30 days.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione

CORN, SWEET―Wild Proso Millet Control
Biology and management  Wild proso millet mimics sweet corn growth. Seeds mature before corn harvest, facilitating spread with machinery. Seed longevity in soil, however, is relatively short (3 to 5 yr). Rotating to grass seed or summer annual broadleaf crops helps deplete the seedbank if wild proso millet is not allowed to produce seed. Wild proso millet seedlings emerge erratically throughout the season because of inherent seed dormancy, which is strongest for black-seed types. Cultivation that brings new seeds to the surface, or irrigation and rain, often cause a new crop of weed seedlings to emerge.
Selective herbicides that suppress or control wild proso millet include EPTC, S-metolachlor, dimethenamid-P, nicosulfuron, and topramezone. In fields with a high density of seeds, control efforts may need a preplant herbicide such as EPTC, followed by a preemergence herbicide, followed by cultivation(s) or another postemergence herbicide. Both topramezone and tembotrione provide good control of wild proso millet up to 6 inches tall, but do not provide residual control.      
CORN, SWEET―Yellow  Nutsedge Control
•  EPTC or
•  butylate
See “Corn, Preplant-incorporated” section in this chapter. (Suppresses yellow nutsedge emergence but does not kill nutsedge tubers.)
•  S-metolachlor
See “Corn, Preemergence, Soil-applied” section in this chapter. (Applications inhibit new tuber formation and reduce infestations).
•  bentazon
See “Corn, Postemergence” section in this chapter. (Controls tubers in Oregon with split treatments applied in warm weather.)
•  atrazine
Rate  Consult label.
Time  Apply as a single or split applications according to one of six alternative methods listed on label.
Remarks  Yearly applications or use of other herbicides can reduce populations if a few plants survive growing season.
Caution  A restricted-use herbicide. Consult label for planting sensitive crops within 12 to 24 mo, depending on time of application and total amount applied.
Site  of action  Group 5: photosystem II inhibitor
Chemical family  Triazine
CORN, SWEET―Canada Thistle Control
•  bentazon
See “Corn, Postemergence” section in this chapter.
•  2,4-D
See “Corn, Postemergence” section in this chapter.
•  glyphosate (numerous product names)
Rate  Consult labels.
Time  Apply at late-bud to early-bloom stage of thistle but before corn silking.
Remarks  Spot-spray thistle patches, eliminating weed and crop in the treated area. Spray before corn silking to avoid residue in harvested crop. Inhibits production of three amino acids and protein synthesis.
Caution  Do not treat more than 10% of the acreage.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted

breakhere  Herbicide Effectiveness in Sweet Corn
	Preplant incorporated or preemergence		Postemergence	
	atrazine
(Atrazine)1	mesotrione 
(Callisto)	S-metolachlor
( Dual II Magnum or Dual Magnum) 	EPTC (Eradicane)
butylate (Sutan)	Dimethenamid-P
(Outlook)	pendimethalin
(Prowl)2		nicosulfuron
Accent)3	carfentrazone
(Aim)4	atrazine
(Atrazine)5	bentazon
(Basagran)	mesotrione (Callisto)	topramezone (Impact)	2,4-D	
Annual Grasses
Wild proso millet
Panicum miliaceum	
P	
P	
F	
F	
G	
G		
G-E	
VP	
P	
VP	
P	
E	
VP	
Barnyardgrass
Echinochloa crus-galli	F	P	G	G	E	G		G	VP	G	VP	P	E	VP	
Witchgrass
Panicum capillare	P	P	E	E	E	G-E		G	P	P	VP	P	G	VP	
Broadleaves
Pigweed
Amaranthus spp. 	
F-E	
G	
G	
F	
G	
G		
G	
G	
F-E	
G	
G	
E	
G	
Lambsquarters
Chenopodium spp. 	E	G	F	G	P	G		P	G	E	E	G	E	F	
Nightshade
Solanum spp. 	G	G	F	G	G	P		VP	G	G	G	G	E	F	
Smartweed
Polygonum punctatum	G	G	P	VP	F	F		P	G	G	E	G	E	F	
Purslane
Portulaca oleracea	G	G	F	G	G	G		P	F	G	P	G	―	P	
Perennials
Yellow nutsedge
Cyperus esculentus	
F	
P	
G	
G	
G	
P		
F	
VP	
F	
F	
F	
P	
VP	
Canada thistle
Cirsium arvense	P	P	VP	P	VP	P		F	VP	F	F	VP	P	F	
Quackgrass
Elytrigia repens	F	P	VP	F	P	P		G	VP	F	VP	VP	VP	VP	
E = Excellent     G = Good    F = Fair     P = Poor     VP = Very poor or no effect
1Depends on level of triazine resistance
2May cause corn to lodge
3Do not use with organophosphate insecticides
4Must be applied to small seedlings for good effectiveness
5Must be applied with crop oil concentrate to small weeds
6Must be directed to prevent corn injury

breakhere  Cucurbit and Vine Crops
Cantaloupe, cucumber, pumpkin, squash, and watermelon
Ed Peachey
Revised November 11, 2008
CUCURBIT AND VINE CROPS―Site Preparation, Stale Seedbeds, and Selective Postemergence Applications
See “Site Preparation,” “Registered Uses for Glyphosate,” and “Registered Uses of Aim Herbicide in Food Crops” at the beginning of the Vegetables section in this handbook.
CUCURBIT AND VINE CROPS―Preplant Incorporated
•  bensulide (Prefar 4-E)
Rate  5 to 6.lb ai/A (5 to 6 quarts/A)
Time  Apply preplant and incorporate 0.5 to 1 inch deep simultaneously or immediately after application by cross-disking or using a power take-off rotary tiller.
Remarks  Sometimes the first flush of weeds must be controlled with cultivation before the herbicide begins to control grass. Consult label for planting sensitive crops following treatment. Inhibits roots of seedlings. Can be tank-mixed with Alanap to improve spectrum of weed control.
Caution  Do not apply more than once every 12 mo. 
Site of action  Group 8: lipid synthesis inhibitor but not an ACCase inhibitor
Chemical family  Organophosphorus
CUCURBIT AND VINE CROPS―Preplant or Preemergence Surface
•  glyphosate (Touchdown HiTech)
winter squash, Oregon only
Rate  0.39 to 0.78 lb ai/A (10 to 20 fl oz/A)
Time  Apply to emerged annual weeds after planting winter squash in spring but before crop emerges. May be mixed with residual herbicides.
Remarks  Oregon special local needs label OR-050006 in Benton, Lane, Linn, and Marion counties.
Caution  Do not apply if crop seeds are exposed because of poor row closure during planting. Do not apply if the radicle has emerged or if soil covering the seeds is cracking. Do not use on soils with less than 1% organic matter.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  naptalam (Alanap-L)
cucumber, melons (cantaloupe, musk, honeydew, casaba), and watermelon
Rate  0.5 to 1 lb ai/A (1 to 2 gal/A)
Time  Preemergence immediately after planting. Water is needed to incorporate herbicide.
Remarks  Registration voluntarily withdrawn but no time limit on selling or using Alanap. Primarily grass control and often used in tank-mixes with Prefar (bensulide, preplant incorporated or post plant surface) and Command (clomazone) .
Caution  Do not use under adverse conditions in the spring with extended cold and soil temperatures below 60°F.
Site of action  Group 19: inhibits indole acetic acid transport
Chemical family  Phthalamate
•  clomazone (Command 3ME) 
preplant surface, pretransplant surface, and postplant surface; on all cucurbits
Rate  0.15 to 0.75 lb ai/A (0.4 to 2 pints/A) depending on crop: cucumbers 0.4 to 1 pint/A; melons 0.4 to 0.67 pint/A; summer squash 0.67 to 1.33 pints/A; winter squash including processing pumpkin 0.67 to 2 pints/A.
Time  Apply using a boom mounted on front of incorporation equipment to ensure immediate incorporation at 1 inch.
Remarks  See label for crop-rotation restrictions for up to 16 mo after treatment. Plant crop seed below treated layer. The new formulation is designed to reduce or minimize drift but requires moisture to activate. Avoid overlaps in spraying and in treating very sandy soils. Inhibits chlorophyll development.
Caution  May discolor fruit of some orange varieties. Do not use on NK530, NK580, 'Turk's turban', 'Golden Delicious', all banana types and all other Cucurbita maxima that have a pink or burnt-orange color at harvest. Do not use on jack-o-lantern pumpkins. Clomazone may inhibit development of orange pigments. Before applying, check adjacent properties and avoid spraying within 300 to 1,200 ft of desirable plants. Sensitive crop and sites include landscapes, orchards, vegetable gardens, berry patches, and property lines. Do not graze cover crops or harvest food or feed within 9 mo of applying or allow livestock to graze treated plants. 
Site of action  Group 13: inhibits DOXP synthase
Chemical family  Isoxazolidinone
•  S-metolachlor (Dual Magnum)
pumpkin (Group 9B; including winter squash), inter-row or interhill only
Rate  0.95 to 1.27 lb ai/A (1 to 1.33 pints/A)
Time  Apply preemergence or postemergence before weeds germinate or yellow nutsedge emerges.
Remarks  Leave 1 ft of untreated area over the row, or 6 inches to each side of the planted hill and/or any emerged pumpkin foliage (inter-row or interhill means not directly over the planted seed or young pumpkin plants). Use the lower rate on soils light in texture (loamy sand or lighter) and low in soil organic matter (less than 3%).
Caution  Consult label for specific rates, depending on soil texture and especially organic matter, or for restrictions on planting sensitive crops within 4 to 5 mo. Inhibits roots and shoots. Preharvest interval is 30 days.
Site of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Chloroacetamide
•  dimethenamid-P (Outlook)
winter squash (var. 'Golden Delicious'), Oregon and Washington only
Rate  0.56 to 0.84 lb ai/A (12 to 18 fl oz/A)
Time  Apply postplant, preemergence, and irrigate with 0.5 inch water to activate herbicide.
Remarks  Supplemental label. Preharvest interval is 90 days. Planting at 1.5 inches or below will help to mitigate potential crop injury.
Caution  Do not apply more than 21 fl oz/A per year. Replanting winter squash is not recommended if there is a crop failure. Other labeled crops can be planted immediately; cereals can be planted within 4 mo of the Outlook application. Excessive rain after planting may temporarily injure crop.
Site of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Chloroacetamide
•  ethalfluralin (Curbit EC)
Rate  1.13 to 1.69 lb ai/A (3 to 4.5 pints/A)
Time  Apply preemergence surface and activate with 0.5 inch of irrigation within 2 to 5 days, or cultivate soil surface above seed. Crop may be injured with excessive rain or irrigation or if seeding is too shallow.
Remarks  Adjust rates depending on soil texture and organic matter content.
Caution  Do not graze or apply to wet or cloddy soils. Note replanting restrictions for sugar beets and red beets listed on label. (Inhibits mitosis, primarily in shoots.)
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
•  ethalfluralin + clomazone (Strategy)
Rate  2 to 6 pints/A, depending on soil texture (see label)
Time  Apply only as a postplant surface treatment before crop and weeds emerge. Activate with 0.5 inch of irrigation within 2 to 5 days, or cultivate soil surface above seed. Crop may be injured with excessive rain or irrigation or if seeding is too shallow.
Remarks  Adjust rates depending on soil texture and organic matter content. Do not preplant-incorporate, as crop will be injured. Inhibits mitosis, primarily in shoots.
Caution  Avoid drift onto neighboring plants. Clomazone will make affected plants turn white. Do not graze or apply to wet or cloddy soils. Note replanting restrictions for sugar beets and red beets listed on label.
Site of action  (ethalfluralin) Group 3: microtubule inhibitors; (clomazone) Group 13: inhibits DOXP synthase
Chemical family  (ethalfluralin) dinitroaniline; (clomazone) isoxazolidinone
•  halosulfuron-methyl (Sandea)
Rate  0.375 to 0.75 oz ai/A (0.5 to 1 oz/A) for cucumbers and other cucurbits approved for directed applications in row-middles. 0.375 to 0.56 oz ai/A (0.5 to 0.75 oz/A) for processing winter squash and pumpkins. Consult label for the diversity of rates recommended depending on crop and method of planting.
Time  Apply before emerging crop cracks the soil, before transplanting, or before seeding or transplanting under plastic mulch.
Remarks  To control broadleaf weeds and nutsedge. Adjust rates, depending on soil texture and organic-matter content. Can be applied preemergence surface as a tank-mix with Outlook (dimethenamid-P) in processing squash to enhance lambsquarters control. Use the 0.5-oz/A rate to avoid crop stunting if tank-mixing with Outlook and if wet, cold soil conditions are expected.
Caution  Crop growth may be stunted briefly after emergence. Consult label for rotation crops, soil-applied organophosphate insecticides, and other precautions. Do not exceed 1 oz/A herbicide per year. Preharvest interval is 30 days for squash, cucumbers, and pumpkin, 57 days for melons.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea 
•  terbacil (Sinbar)
watermelon only
Rate  0.1 to 0.2 lb ai/A (2 to 4 oz/A, to a maximum of 4 oz/A per year)
Time  Apply before transplanting or before crop emerges if direct-seeding watermelon.
Remarks  Supplemental label for watermelon only. Moisture is required to activate the herbicide and should arrive within 2 wk of planting. May be applied preemergence under plastic mulch. Preharvest interval is 70 days.
Caution  Do not use on sand or gravel soil types. Use with caution if soil organic matter is less than 1%. Do not replant any crop for 2 yr after applying terbacil.
Site of action  Group 5: photosystem II inhibitor
Chemical family  Uracil
•  bensulide (Prefar 4-E)
Rate  5 to 6 lb ai/A (5 to 6 quarts/A)
Time  Apply before crop and weeds emerge, preferably soon after planting; follow with sprinkler irrigation to wet soil 2 to 4 inches deep.
Remarks  For furrow irrigation, thoroughly saturate bed top. Germinated or seedling weeds must be cultivated before application. Consult label for planting sensitive crops after treatment.
Caution  Do not apply more than once every 12 mo.
Site of action  Group 8: lipid synthesis inhibitor but not an ACCase inhibitor
Chemical family  Organophosphorus
CUCURBIT AND VINE CROPS―Postemergence
•  halosulfuron-methyl (Sandea)
broadcast sprays on cucumbers, cantaloupe, processing winter squash, and pumpkins only; selective sprays allowed on other cucurbit crops
Rate  0.375 to 0.75 oz ai/A (0.5 to 1 oz/A) depending on soil type for cucumbers and other cucurbits; 0.375 to 0.56 oz ai/A (0.5 to 0.75 oz/A) for processing winter squash and pumpkins.
Time  Apply postemergence to seeded or transplanted crops that are well established and that have two to five leaves (preferably four to five leaves), and before the first female flowers appear.
Remarks  Results in the Pacific Northwest indicate potential for crop injury or delayed flowering with broadcast postemergence treatments. Primary use is nutsedge suppression. Applications are allowed for most cucurbit crops if spray is directed to row middles after planting or transplanting, or if applied with shielded sprayers that prevent herbicide contact with the crop. Avoid irrigation or rain within 4 hr after treatment.
Caution  Crop growth may be stunted or become yellow briefly after treatment. Consult label for rotation crops, soil-applied organophosphate insecticides, and other precautions. Do not exceed 2 oz/A herbicide per year. Preharvest interval is 30 days for squash, cucumber, and pumpkin, 57 days for melons.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  sethoxydim (Poast)
Rate  0.19 to 0.28 lb ai/A (1 to 1.5 pints/A)
Time  Apply at optimum growth stage listed on the label.
Remarks  Identify susceptible grasses and add 2 pints/A nonphytotoxic crop oil concentrate to improve leaf absorption. Control often is erratic on grasses stunted or stressed from drought, high temperatures, or low fertility. Resistant grasses include annual bluegrass and all fine fescues, but quackgrass can be suppressed. Inhibits fatty acid production, cell membranes, and new growth.
Caution Preharvest interval is 14 days (3 days for cantaloupe). Do not exceed 3 pints/A per season.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione
•  clethodim (Prism; Select 2C in Oregon only)
Rate  Consult label for rate required to control different grasses.
Time  Apply to actively growing grasses at recommended weed heights.
Remarks  Add crop oil concentrate as described on label.
Caution  Consult labels for maximum rate per application and season. Preharvest interval is 14 days.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione
CUCURBIT AND VINE CROPS―Postemergence Layby Treatments
•  trifluralin (Treflan 4L or HFP)
Rate  0.5 to 1.0 lb ai/A (1 to 2 pints/A)
Time  Apply as a directed spray between rows when crop has three to four true leaves.
Remarks  Incorporate 2 to 3 inches deep, using rolling cultivators set to throw soil toward plants in row. Spray only once per year. Consult label for restrictions on planting sensitive crops within 12 mo. (Inhibits mitosis, primarily in shoots.)
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
•  ethalfluralin (Curbit)
Rate  1.13 to 1.69 lb ai/A (3 to 4.5 pints/A)
Time  Apply in bands between rows after planting or transplanting. Activate with 0.5 inch irrigation within 2 to 5 days or cultivate soil 1 to 2 inches deep.
Remarks  Adjust rates depending on soil textures and organic matter.
Caution  Do not graze or apply to wet cloddy soils. Note replanting restrictions on label for sugar beets and red beets. (Inhibits mitosis, primarily in shoots.)
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
•  DCPA (Dacthal W-75)
cucumbers and melons (all types) only
Rate  4.5 to 10.5 lb ai/A (6 to14 lbs/A)
Time  Apply after plants have four to five true leaves, after cultivation and weeding but before any new weeds become established.
Remarks  Performs poorly in western Oregon and Washington. Results improve with rain or overhead irrigation immediately after application. Consult label for restrictions on planting sensitive crops within 8 mo. Inhibits mitosis.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Phthalic acid

Garlic
Ed Peachey
Revised November 24, 2008
GARLIC―General Weed Management Strategy
Garlic requires nearly perfect weed control because it emerges slowly and matures in 10 to 11 mo, and its short vertical leaves never form a canopy. Growers, therefore, often control all weedy vegetation immediately before the crop emerges (often in wet weather), applying a selective soil-applied herbicide for winter weed control and adding treatments in spring, depending on specific weed infestations.
GARLIC―Site Preparation, Stale Seedbeds, and Selective Postemergence Applications
See “Site Preparation,” “Registered Uses for Glyphosate,” and “Registered Uses of Aim Herbicide in Food Crops” at the beginning of the Vegetables section in this handbook.
GARLIC―Preemergence 
•  paraquat (Gramoxone Inteon; 2 lb paraquat cation/gal)
Rate  0.63 to 1 lb cation/A (2.5 to 4 pints/A); use higher rates for heavy weed infestation or wild oat control
Time  Apply just before crop emerges to emerged weeds only. Add a nonionic surfactant or crop oil concentrate as label specifies, taking care to avoid anionic formulations that react in the tank to form insoluble precipitates.
Remarks Acts as contact; absorbs energy produced by photosynthesis, forming peroxides that disrupt living cells.
Caution  A restricted-use pesticide. Do not ingest or inhale spray mist. Wear protective face shields, respirators, and clothing.
Site of action  Group 22: photosystem 1 electron diversion
Chemical family  Bipyridilium
•  pendimethalin (Prowl H2O and 3.3EC)
Rate  0.5 to 1.49 lb ai/A (1.2 to 3.6 pints/A)
Time  Apply either preemergence soon after planting, postemergence when garlic has one to five true leaves, or split the treatments but do not exceed 3.6 pints/A product per crop except for dodder control (see label).
Remarks  Adjust rates for soil texture and organic matter. Existing weeds must be destroyed; rain or overhead irrigation must be within 7 days to activate. Inhibits mitosis in both shoots and roots.
Caution  Do not feed or graze field residues. Preharvest interval is 45 days.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
•  ethofumesate (Nortron SC)
Rate  Preemergence―0.5 to 1 lb ai/A (16 to 32 fl oz/A) depending on soil texture. Weed control diminishes in fine-texture soils and soils with high organic matter.
Time  Apply after planting and activate with at least 0.5 inch water.
Remarks  Do not use smaller than 50 mesh screen and avoid overlaps, which may increase risk of crop injury.
Caution  May cause temporary leaf fusion, distortion, and stunting when used as label directs and under normal growing conditions. If crop is lost due to unfavorable growth conditions after application, do not plant anything except sugar beets, table beets, onions, garlic, shallots, or ryegrass.
Site of action  Group 16: unknown
Chemical family  Benzofuran
•  flumioxazin (Chateau)
Rate  3 oz ai/A (6 oz/A Chateau WDG and SW)
Time  Prior to garlic emergence.
Remarks  Supplemental label for use in garlic. Application should be made within 3 days of planting, and before weeds emerge.
Caution  Toxic to aquatic invertebrates. Do not apply directly to water. Clean spray tank carefully before applying other herbicides.
Site of action  Group 14: protoporphyrinogen oxidase (PPO) inhibitor
Chemical family  Diphenylether
GARLIC―Postemergence
•  bromoxynil (Buctril or Broclean)
Rate  0.375 to 0.5 lb ai/A (1.5 to 2 pints/A Buctril)
Time  Apply postemergence to weeds less than 4 inches tall, preferably in the cotyledon stage.
Remarks  Finish treatments before garlic is 12 inches tall. Use higher rate on larger weeds.
Caution  Do not ingest or inhale spray mist. Prevent contact with skin. Wear protective face shields, respirators, and clothing. Preharvest interval is 112 days.
Site of action  Group 6: Photosystem II inhibitor
Chemical family  Nitrile
•  dimethenamid-P (Outlook)
Rate  0.56 to 0.84 lb ai/A (12 to 18 fl oz/A) on coarse soils and 0.84 to 0.98 ai/A (18 to 21 fl oz/A) in medium- or fine-texture soils. May be applied in a single application only. Do not exceed 21 fl oz/A per season. 
Time Apply postemergence from the two-true-leaf stage until at least 30 days before harvest.
Remarks  Postemergence by ground, chemigation, aerial, impregnated onto dry bulk fertilizer, or layby (including postemergence-directed). Refer to the EPA-approved labels for specific application methods and requirements.
Caution  Applying before the two-true-leaf stage may significantly injure the crop. To avoid harming endangered plant species, comply with the following mitigation measures where these species grow in the listed counties (including Jackson, Klamath, Marion, and Washington counties in Oregon). Aerial applications must leave a 150-ft untreated buffer between treatment area and endangered plant populations. Ground applications must use low-pressure nozzles that produce only medium to coarse or very coarse droplets and leave a 35-ft untreated buffer between treatment area and endangered plant populations.
Site of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Chloroacetamide
•  ethofumesate (Nortron SC)
Rate  0.5 lb ai/A (16 fl oz/A) with up to four evenly spaced sequential applications
Time  Postemergence.
Remarks  Do not use smaller than 50 mesh screen and avoid overlaps, which may increase risk of crop injury. In postemergent applications, rain or irrigation within 6 hr after applying may reduce weed control.
Caution  May cause temporary leaf fusion, distortion, and stunting when used as label directs and under normal growing conditions. If crop is lost due to unfavorable growth conditions after application, do not plant anything except sugar beets, table beets, onions, garlic, shallots, or ryegrass.
Site of action  Group 16: unknown
Chemical family  Benzofuran
•  oxyfluorfen (GoalTender)
Rate  0.12 to 0.25 lb ai/A (0.25 to 0.5 pint/A)
Time  Apply postemergence to garlic with two fully developed true leaves.
Remarks  Multiple treatments may be required as new weeds emerge, but do not exceed 0.5 lb ai/A per season. Use a clean sprayer and do not mix with oils, surfactants, or other agricultural chemicals. Acts as a selective contact that disrupts cell membranes.
Caution  Do not apply to garlic under any stress. Leaves may curl slightly, and young plants sometimes become prostrate on the soil surface for 1 to 2 days, but yields have not been reduced. Preharvest interval is 60 days. 
Site of action  Group 14: protoporphyrinogen oxidase inhibitor
Chemical family  Diphenylether
•  carfentrazone (Aim)
Rate  up 0.031 lb ai/A (0.5 to 2 fl oz/A Aim EC) per application in at least 10 gal/A of finished spray
Time  Apply with hooded sprayer between rows of emerged crop.
Remarks  See the table of approved uses on vegetable crops under “Selective Postemergence Applications” at the beginning of the Vegetables section of this handbook.
Site of action  Group 14: protoporphyrinogen oxidase inhibitor
Chemical family  Triazinone
•  fluazifop (Fusilade DX)
Rate  Refer to label directions for specific grassy weeds.
Time  Apply to actively growing grasses as a directed spray with 1% crop oil or 0.25% nonionic surfactant.
Remarks  Identify grasses, and adjust rates for susceptibility and stage of weed growth as on label. Results often are erratic on grasses stressed from lack of vigor, drought, high temperature, or low fertility. More mature grasses and quackgrass can be controlled but may require two applications. Annual bluegrass and all fine fescues resist treatment. Inhibits fatty acid production, cell membranes, and new growth.
Caution  Preharvest interval is 45 days. Do not exceed 48 fl oz/A per year. Grazing is prohibited.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Aryloxyphenoxy propionate
•  sethoxydim (Poast)
Rate  0.19 to 0.28 lb ai/A (1 to 1.5 pints/A) depending on target grass species
Time  Apply at optimum growth stage listed on label.
Remarks  Control is often erratic on grasses stunted or stressed from drought, high temperatures, or low fertility. Resistant grasses include annual bluegrass and all fine fescues, but quackgrass can be suppressed. Add 2 pints/A nonphytotoxic crop oil concentrate or methylated seed oil to improve leaf absorption and efficacy. Inhibits fatty acid production, cell membranes, and new growth.
Caution  Preharvest interval is 30 days. Do not exceed 4.5 pints/A per season.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione
•  clethodim (Select 2EC; or Prism in Oregon only)
Rate  0.094 to 0.25 lb ai/A (6 to 16 fl oz/A Select)
Time  Apply to actively growing grass weeds, including annual bluegrass, at growth stage listed on label.
Remarks  Read label carefully for adjuvant instructions and about effects of rain within 1 hr, application of other pesticides, or cultivation.
Caution  See labels for maximum rates per application and season. Preharvest interval is 45 days.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione

Leaf Crops 
(Crop groups 4A, 2, and 19) 
Lettuce, endive (escarole), spinach, New Zealand spinach, Swiss chard, and arugula (Leafy Greens Subgroup 4A), Chicory (Leaves of Root and Tuber Vegetables Group 2), and cilantro/coriander (Herbs Group 19)
Ed Peachey
Revised November 11, 2008
LEAF CROPS―General Weed Management Strategy
Direct-seeded lettuce requires a couple of cultivations and a hand thinning or weeding; transplanted lettuce matures in 45 days after one or two cultivations with a minor hand weeding.
LEAF CROPS―Site Preparation, Stale Seedbeds, and Selective Postemergence Applications
See “Site Preparation,” “Registered Uses for Glyphosate,” and “Registered Uses of Aim Herbicide in Food Crops” at the beginning of the Vegetables section in this handbook.
LEAF CROPS―Preemergence
•  benefin (Balan)
lettuce only, direct-seeded and transplanted 
Rate  1.2 to 1.5 lb ai/A (2 to 2.5 lb/A)
Time  Apply from 10 wk to just before planting; incorporate within 8 hr by cross-disking or with a power-takeoff rotary tiller.
Remarks  May apply through center-pivot and lateral-move irrigation systems. Spray only once; avoid overlapping. See label about planting sensitive crops within 10 to 12 mo. Control is poor for many broadleaf weeds. Inhibits mitosis in shoots and roots.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
•  bensulide (Prefar 4E)
lettuce, endive, and arugula only; will severely injure spinach, New Zealand spinach, and Swiss chard
Rate  5 to 6 lb ai/A (5 to 6 quarts/A)
Time  Preplant or preemergence.
Crops  Lettuce and other leafy vegetables including but not limited to arugula, Brassica leafy vegetables (see label), cardoon, celery, chicory, Chinese celery, chervil, cress, dock, endive, Florence fennel, and parsley. Do not use on spinach or Swiss chard.
Remarks  Incorporate before planting in top 1 to 2 inches of soil by cross-disking or using a power take-off  rotary tiller; or apply preemergence soon after planting, before crop and weeds begin germination, and activate with 1 inch overhead moisture. Sometimes the first flush of weeds must be controlled with cultivation before herbicide begins to control grass. See label for planting sensitive crops after treatment. Inhibits roots of seedlings.
Caution  Do not apply more than once per year. Primarily a grass herbicide. 
Site of action  Group 8: lipid synthesis inhibitor but not an ACCase inhibitor
Chemical family  Organophosphorus
• trifluralin (Agristar Trifluralin EC)
endive and chicory only
Rate  0.5  to 1 lb ai/A (1 to 2 pints/A) depending on soil type and organic matter content (see label)
Time  Apply preplant and incorporate in top 1 to 2 inches of soil by cross-disking or using a power take-off rotary tiller.
Caution  Consult label for lengthy crop rotation restrictions when using this product.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
•  pronamide (Kerb 50W)
lettuce and endive only, direct-seeded and transplant
Rate  1 to 2 lb ai/A (2 to 4 lb/A)
Time  Apply preplant and incorporate thoroughly 2 to 3 inches deep, or apply preemergence at or soon after planting and activate with surface moisture to reduce loss of herbicide.
Remarks  See label for some sensitive varieties and for planting sensitive crops within 12 mo. Primarily a grass herbicide. Inhibits mitosis.
Caution  A restricted-use pesticide. Preharvest interval is 55 days.
Site of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Chloroacetamide
•  cycloate (Ro-Neet)
spinach only
Rate  2 to 3 lb ai/A (2.7 to 4 pints/A)
Time  Apply preplant to soil dry enough for thorough mixing; incorporate 2 to 3 inches deep immediately by cross-disking or using a rotary tiller within minutes after application.
Remarks  Use on mineral soils only. Seed may be planted immediately. Sprinkler irrigation may be used to incorporate the herbicide in the Pacific Northwest if the soil is dry to at least 0.5 inch, the irrigation is within 5 days, and irrigation wets the soil to 4 inches. Inhibits shoot growth.
Caution  No preharvest interval listed.
Site of action  Group 8: lipid synthesis inhibitor but not an ACCase inhibitor
Chemical family  Thiocarbamate
LEAF CROPS―Postemergence
•  phenmedipham (Spin-Aid)
spinach only
Rate  0.49 to 0.98 lb ai/A (3 to 6 pints/A)
Time  Apply any time spinach is past four- to six-leaf stage and before weeds are at the two-leaf stage.
Remarks  Avoid applying if weather may change rapidly from cool and cloudy to warm and sunny, or if spinach is stressed from insect, disease, or cultivation injury. Tip burn or temporary growth retardation and chlorosis may occur; plants usually recover within 10 days. 
Caution  Preharvest interval is 40 days. Avoid diluting herbicide more than 1 quart/7 gal water in spray tank, which can cause the chemical to precipitate.
Site of action  Group 5: photosystem II inhibitor
Chemical family  Phenylcarbamate 
•  clopyralid (Stinger)
spinach only
Rate  Apply 0.063 to 0.124 lb ae/A (0.16 to 0.33 pint/A) with ground equipment in total spray volume of 10 gal/A or more.
Timing  Apply at the two- to five-leaf stage of spinach. Stinger controls wild buckwheat when applied in the one- to three-leaf stage of growth, before vining begins. Apply Stinger to clover from weed emergence up to the five-leaf stage of growth. To suppress sowthistle, apply Stinger from rosette up to bud stage.
Remarks  Controls wild buckwheat, sweet clover, prickly lettuce, common ragweed, and galinsoga. Suppresses sowthistle.
Caution  Preharvest interval is 21 days. Make one to two broadcast applications per crop per year, not to exceed 0.5 pint/A. Note crop rotational intervals on label.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  sethoxydim (Poast)
Rate  0.188 to 0.28 lb ai/A (1 to 1.5 pints/A)
Time  Apply at optimum growth stage listed on the label.
Remarks  Identify susceptible grasses, and add 2 pints/A nonphytotoxic crop oil concentrate to improve leaf absorption. Control often is erratic on grasses stunted or stressed from drought, high temperatures, or low fertility. Resistant grasses include annual bluegrass and all fine fescues, but quackgrass can be suppressed. Inhibits fatty acid production, cell membranes, and new growth.
Caution  Preharvest interval is 15 days for spinach and leaf lettuce, 30 days for head lettuce. Do not exceed 3 pints/A per season. Avoid applying when temperatures exceed 90°F or when relative humidity exceeds 60%.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione
•  clethodim (Select or Prism)
Rate  0.094 to 0.125 lb ai/A (6 to 8 oz/A Select) depending on target weed species and growth stage
Time  Apply to actively growing grass weeds, including annual bluegrass, at growth stages indicated on label.
Remarks  Read label carefully for adjuvant instructions, and note effects of rain within 1 hr, application of other pesticides, and cultivation.
Caution  See labels for maximum rates per application and season. Preharvest interval is 14 days.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione
•  fluazifop (Fusilade DX)
endive only
Rate  0.125 to 0.188 lb ai/A (8 to 12 oz/A) depending on target weed species and growth stage.
Time  Apply to actively growing grasses as a directed spray with 1% crop oil or 0.25% nonionic surfactant.
Remarks  Identify grasses, and adjust rates for susceptibility and stage of weed growth as on label. Results often are erratic on grasses stressed from lack of vigor, drought, high temperature, or low fertility. More mature grasses and quackgrass can be controlled but may require two applications. Annual bluegrass and all fine fescues resist treatment. Inhibits fatty acid production, cell membranes, and new growth
Caution Preharvest interval is 28 days. Do not exceed 48 oz/A per year. Grazing is prohibited.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Aryloxyphenoxy propionate
•  triflusulfuron methyl (UpBeet)
supplemental labels in the PNW for endive and chicory only
Rate  0.25 oz ai/A (0.5 oz/A)
Time  Apply when endive or chicory plants have developed one true leaf (two cotyledons and one true leaf). Use at least two sequential applications for best results. Apply 5 to 10 days apart, depending on weed size.
Remarks  Apply to small actively growing weeds. Nonionic surfactants may be used at 0.25% v/v but may increase risk of crop injury. Crop oil concentrates are not recommended. Controls pigweed, kochia, shepherdspurse, and velvetleaf.    
Caution  Discoloration may be noted in some cases but effects are temporary. Do not contaminate water bodies, or rinse or flush spray near roots of trees and desirable plants, or injury may result.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea 

Onions
Dry bulb and green, leeks, shallots, and spring onions
Ed Peachey
Revised November 24, 2008
ONIONS―Site Preparation, Stale Seedbeds, and Selective Postemergence Applications
See “Site Preparation,” “Registered Uses for Glyphosate,” and “Registered Uses of Aim Herbicide in Food Crops” at the beginning of the Vegetables section in this handbook.
ONIONS―Preplant
•  S-metolachlor (Dual Magnum)
fall preplant for yellow nutsedge control in dry bulb onions; Oregon and Idaho only
Rate and Time  East of Cascade―apply 1.27 lb ai/A (1.33 pints/A) in fall after crop harvest but before freeze-up. Fall applications of Dual Magnum can be surface-applied. However, recent experience at the OSU Malheur Experiment Station indicates onions may be injured if Dual Magnum is not sufficiently incorporated in fall and if weather remains cold and wet after onions are planted in spring. To reduce risk of crop injury, apply at least 100 days before planting onion seed, sets, or transplants.
West of Cascades―apply 1.27 lb ai/A (1.33 pints/A) of Dual Magnum in fall. Use low rate on mineral soils and high rate on muck soils. Apply before fall rains begin or after the first light rain. Do not incorporate Dual Magnum with tillage, as this will reduce yellow nutsedge control. To reduce risk of crop injury, apply at least 130 days before planting onion seed, sets, or transplants.
Remarks  Indemnified special local needs labels OR-040009 and ID-9900016 available at www.farmassist.com. Dual Magnum inhibits roots and shoots formation.
Caution  Risk of crop injury is greater on light-texture soils and at higher application rates. Tank-mixes with other pesticides may increase potential of crop injury. Only one application in fall is recommended. No more than 1.33 pint/A in a single fall preplant application. Avoid areas with shallow groundwater and directly applying to water.
Site of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Chloroacetamide
•  bensulide (Prefar 4-E)
not for use in Willamette Valley of Oregon; dry bulb onions and shallots only
Rate  5 to 6 lb ai/A (5 to 6 quarts/A)
Time  Fall application, during bed construction―apply after markout when soil is below 60°F. Spray over beds and incorporate with water or mechanically. Spring application―apply preplant incorporated or preemergence in band or broadcast and incorporate with rain or irrigation. Apply enough overhead irrigation to wet 2 to 4 inches of soil or enough furrow irrigation to wet across seed beds.
Remarks  Special local needs label available (WA-940010). Shallow mechanical incorporation can be substituted to maintain the herbicide above the onion seed. If mechanically incorporated, use spike-tooth harrow, smizer roller, or similar equipment to maintain shallow and uniform layer of herbicide within the upper 1 inch of soil for sandy soils or the upper 0.5 inch for loam soils. Use low rates on sandy soils. Will not control germinated weed seedlings. Inhibits roots of seedlings.
Site of action  Group 8: lipid synthesis inhibitor but not an ACCase inhibitor
Chemical family  Organophosphorus
ONIONS―Preemergence, Delayed Preemergence, Early Postemergence
•  ethofumesate (Nortron SC)
dry bulb onions and shallots only
Rate  Preemergence―0.5 to 1 lb ai/A (16 to 32 fl oz/A) depending on soil texture. Weed control diminishes in soils with fine texture or high organic matter. Postemergence―0.5 lb ai/A (16 fl oz/A) with up to four evenly spaced sequential applications.
Time  Apply after planting and activate with at least 0.5 inch of water, or apply after crop emerges.
Remarks  Do not use smaller than 50 mesh screen and avoid overlaps, which may increase risk of crop injury. For postemergent applications, rain or irrigation within 6 hr after application may reduce weed control.
Caution  May cause temporary leaf fusion, distortion, and stunting when used as label directs and under normal growing conditions. If crop is lost due to unfavorable growth conditions after application, do not plant anything except sugar beets, table beets, onions, garlic, shallots, or ryegrass.
Site of action  Group 16: unknown 
Chemical family  Benzofuran
•  S-metolachlor (Dual Magnum)
early postemergence for yellow nutsedge control in dry bulb onion; Oregon, Idaho, and Washington
Rate and Time  Apply at two-true-leaf stage of onions at 0.67 to 1.33 pints/A (0.64 to 1.27 lb ai/A). Another application of 0.67 to 1.33 pints/A may be made 21 or more days after the first, if needed, provided Dual Magnum was not applied preplant in fall.
Remarks  Indemnified special local need labels OR-040009 and ID-9900016 are available at www.farmassist.com. The Washington special local need label (WA-990023) is distributed only by the Walla Walla Sweet Onion Growers Association. Excessive rain or cold, wet conditions after application may reduce plant stand and cause stunting and yield loss. Onion tolerance to Dual Magnum increases with increasing onion size.
Caution  Restricted use in Washington. (1) Do not apply within 60 days of harvest. (2) Do not harvest green onions. (3) Do not apply this product through any type of irrigation system. (4) Do not graze animals on green forage or stubble. If a fall preplant application of Dual Magnum was used for nutsedge, only one postemergence application at a maximum rate of 1.33 pints/A is allowed. Do not apply more than 2.68 pints/A to dry bulb onions as a combined total across all application timings and use patterns to produce that crop.
Site of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Chloroacetamide
•  dimethenamid-P (Outlook)
dry bulb onions, garlic, and dry bulb shallots
Rate  0.56 to 0.84 lb ai/A (12 to 18 fl oz/A) on coarse soils and 0.84 to 0.98 lb ai/A (18 to 21 fl oz/A) in medium-texture or fine soils. May be applied in a single application. Do not exceed 21 fl oz/A per season. 
Time  Apply postemergence from the two-true leaf stage until at least 30 days before harvest.
Remarks  Split applications of 10 to 14 oz/A followed by 7 to 14 oz/A are permitted but cannot exceed a total of 21 oz/A. Refer to the EPA-approved labels for specific application methods and requirements.
Caution  Applications before the two-true-leaf stage may significantly injure the crop. Aerial applications must leave a 150-ft untreated buffer between treatment area and endangered plant populations. Ground applications must use low-pressure nozzles that produce only medium to coarse or very coarse droplets and leave a 35-ft untreated buffer between treatment area and endangered plant populations.
Site of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Chloroacetamide
•  pendimethalin (Prowl 3.3EC or Prowl H2O)
dry bulb onions and shallots only, direct-seeded or transplanted
Rate  0.5 to 1.48 lb ai/A (1.2 to 3.6 pints/A Prowl 3.3)
Time  Delayed preemergence for dry bulb onion only (after onion seed germinates but before it emerges); and after onions emerge (two- to nine-true-leaf stage). Delayed preemergence―apply Prowl H2O when 75% of dry bulb onion seed radicals have emerged. Determine radical status by digging onion seedlings at random locations in a field and noting radical length. Plant onions at least 1 inch deep to mitigate risk of injuring them.
Remarks  Special local needs labels are available for delayed preemergence for Prowl H2O (OR‑060008, WA‑070004, and ID‑060009) from several grower associations in both western and eastern Oregon and Washington and in Idaho. Adjust rates according to soil texture. Rain or overhead irrigation is needed within 10 days for activation. Inhibits mitosis, both in shoots and roots.
Caution  Be aware of crop-rotation restrictions, including for sugar beets, winter wheat, and winter barley.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
•  oxyfluorfen (GoalTender, Goal 2XL, or Galigan 2E)
dry bulb onion, green onions (via sprinkler application)
Rate   0.12 to 0.25 lb ai/A (0.25 to 0.5 pint/A GoalTender) in direct-seeded and transplanted onions.
Time  Apply postemergence to onions with two fully developed true leaves while broadleaf weeds have fewer than four true leaves. Goal applications are allowed on green onions through sprinkler irrigation systems (Special local needs label OR‑020027). Read and follow label instructions precisely regarding irrigation interval and all chemigation specifications to minimize environmental hazards.
Remarks  Multiple treatments may be required as new weeds emerge, but do not exceed 0.5 lb ai/A (maximum of 2.5 pints/A per use season). Use a clean sprayer and do not mix with oils, surfactants, or other agricultural chemicals. Apply when susceptible weeds are in the two- to four-leaf stage and actively growing. Acts as a selective contact that disrupts cell membranes.
Caution  Do not apply to onions under any stress. Leaves may curl slightly, and young plants sometimes become prostrate on the soil surface for 1 to 2 days, but yields have not been reduced. Preharvest interval is 45 days. Goal damages some onion varieties more easily than others; ‘Walla Walla’ sweet onions are very sensitive. Check with your seed supplier for information regarding the variety you wish to plant.
Site of action  Group 14: protoporphyrinogen oxidase inhibitor
Chemical family  Diphenylether
•  DCPA (Dacthal Flowable)
Rate 4.5 to 10.5 lb ai/A (6 to 14 pints/A)
Time  Apply after planting to soil surface before weeds germinate and onions emerge.
Remarks  Performs erratically west of the Cascades. In eastern Oregon and Washington, if overhead irrigation is not available, apply and shallowly incorporate herbicide with a nailboard. Rain after incorporation improves weed control. Results improve with overhead irrigation immediately after application. Consult label for planting sensitive crops within 8 mo. Inhibits mitosis.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Phthalic acid

ONIONS―Postemergence
•  bromoxynil (Buctril or Broclean)
Idaho and east of Cascades, dry bulb and green onions only
Rate  0.25 to 0.38 lb ai/A (1 to 1.5 pints/A)
Time  Apply in 50 to 70 gal water for thorough coverage when onions have two to five true leaves. Apply on sunny days when plants are dry and humidity is low. 
Caution  Do not ingest or inhale spray mist, and prevent contact with skin. Wear protective face shields, respirators, and clothing. Do not apply west of Cascades or when protective waxy cuticle on onion leaves may be thin or damaged. Do not add adjuvants. Injury can sometimes occur, even under ideal conditions.
Site of action  Group 6: photosystem II inhibitor
Chemical family  Nitrile
•  trifluralin (Treflan TR-10)
dry bulb onions only
Rate  0.38 to 0.63 lb ai/A (3.75 to 6.26 lb/A broadcast rate)
Time  Apply at layby as a directed spray to the soil between rows, and incorporate immediately with sweeps or rolling cultivators.
Remarks  Use proportionately less when treating area between rows only. Inhibits mitosis in shoots and roots.
Caution  Do not apply to soils with more than 3.5% organic matter, or effectiveness will be reduced. Do not apply preplant or preemergence. Preharvest interval is 60 days. Remove emerged weeds before applying. See label for planting sensitive crops within 12 mo.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
•  carfentrazone (Aim)
Rate  up to 0.031 lb ai/A (0.5 to 2 fl oz/A Aim EC) per application in at least 10 gal/A of finished spray
Time  Apply with hooded sprayer between rows of emerged crop.
Remarks  See the table of approved uses on vegetable crops under “Selective Postemergence Applications” at the beginning of the Vegetables section in this handbook. Hooded sprayers must prevent spray from reaching green stem tissue, foliage, blooms or fruit of the crop.
Site of action  Group 14: protoporphyrinogen oxidase inhibitor
Chemical family  Triazinone
•  paraquat (Gramoxone Inteon)
Rate  0.63 to 1 lb cation/A (2.5 to 4 pints/A)
Time  Apply before, during, or after planting but before crop emerges to control emerged weed seedlings only. 
Remarks  Add a nonionic surfactant or crop oil concentrate according to label specifications, taking care to avoid anionic formulations that react in the tank to form insoluble precipitates. Acts as contact; absorbs energy from photosynthesis, forming peroxides that disrupt living cells.
Caution  A restricted-use pesticide. Do not ingest or inhale spray mist. Wear protective face shields, respirators, and clothes. Do not exceed 4 pints/A per season. Preharvest interval is 60 days. 
Site of action  Group 22: photosystem 1 electron diversion
Chemical family  Bipyridilium
•  fluazifop (Fusilade DX)
dry bulb onions only
Rate  0.125 to 0.188 lb ai/A (8 to 12 oz/A) depending on target weed species and growth stage.
Time  Apply to actively growing grasses with 1% crop oil or 0.25% nonionic surfactant. Results often are erratic on grasses stressed from lack of vigor, drought, high temperature, or low fertility. 
Remarks  Identify grasses; adjust rates depending on susceptibility and stage of weed growth as label instructs. More mature grasses and quackgrass can be controlled but may require two applications. Annual bluegrass and all fine fescues resist treatment. Inhibits fatty acid production, cell membranes, and new growth.
Caution Preharvest interval is 45 days. Do not exceed 3 pints/A per year. Grazing is prohibited. 
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Aryloxyphenoxy propionate
•  sethoxydim (Poast)
Rate  0.19 to 0.28 lb ai/A (1 to 1.5 pints/A) depending on target grass species and growth stage
Time  Apply at optimum growth stage as on label.
Remarks  Identify susceptible grasses, and add 2 pints/A nonphytotoxic crop oil concentrate to improve leaf absorption. Results often are erratic if grasses are stressed from lack of vigor, drought, high temperature, or low fertility. Resistant grasses include annual bluegrass and all fine fescues, but quackgrass can be suppressed. Inhibits fatty acid production, cell membranes, and new growth.
Caution Preharvest interval is 30 days. Do not exceed 4.5 pints/A per season. 
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione
•  clethodim (Select 2EC for dry onions only or Select Max for dry and green onions; supplemental label)
Rate  Consult labels for information on dry and green onion.
Time  Apply to actively growing grass weeds, including annual bluegrass, at growth stage on label.
Remarks  Read label carefully for adjuvant instructions and about effects of rain within 1 hr, applying other pesticides, or cultivation.
Caution  Consult labels for maximum rates per application and season. Preharvest interval is 45 days for dry bulb onions, 14 days for green onions.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione
•  fluroxypyr  (Starane Ultra) 
dry bulb onions only
Rate  0.125 lb ae/A (0.35 pints/A product)
Time  Apply broadcast postemergence from the two-true-leaf stage though the six-leaf stage. Weeds should be 4 to 8 inches tall.
Remarks  Special local needs labels OR-080026 and ID-080007 for control of kochia, volunteer potatoes, and other susceptible broadleaf weeds. Adjuvants are not recommended. Heavy flushes of weeds can be controlled with two sequential applications at 10- to 14-day intervals. Do not exceed 0.7 pint/A or two applications per year. 
Caution  Crop injury may occur with some onion varieties. Applications after the six-leaf stage should be made as a directed spray with drop nozzles. Do not broadcast after the six-leaf stage. Do not apply through any type of irrigation system. Preharvest interval is 42 days. 
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine

ONIONS―Sprout Inhibition
•  maleic hydrazide (Royal MH-30)
Rate 2 lb ai/A (1.33 gal/A)
Time  Apply when bulbs are fully mature, with soft necks and five to eight green leaves, or when about 50% of the tops have fallen but are still green. 
Remarks  Apply at temperatures below 80° to 85°F to avoid crystallization on leaf surfaces. Using a spray adjuvant is suggested in arid regions west of the Rocky Mountains. Avoid early sprays, before maturity, to reduce spongy onions.
Caution  Do not treat seed onions.
Site of action  Not well understood
Chemical family  None generally accepted