Rhubarb
Ed Peachey
Revised November 7, 2008
 •  glyphosate (many products)
Rate  Consult label
Time  Broadcast before crop emerges; hooded and shielded sprayers in row middles, wiper application in row middles after crop emerges.
Remarks  Can apply in winter or early spring before rhubarb shoots or leaves emerge. Over-the-top wipers and directed applications are not permitted once the crop emerge. Treatment with other selective equipment (hooded and shielded sprayers) must be 14 days before harvest.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted
•  paraquat (Gramoxone Inteon, 2 lb paraquat cation/gal)
Rate  0.43 to 0.68 lb ai/A cation (1.7 to 2.7 pints/A)
Time  Apply during dormant season before buds in crown begin to grow.
Remarks  Add nonionic surfactant at 8 fl oz/100 gal spray mix. 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. Add a nonionic surfactant or crop oil concentrate as on label; take care to avoid anionic formulations that form insoluble precipitates in the tank. Do not exceed two applications or 3 pints/A per season.
Site of action  Group 22: photosystem I electron diversion
Chemical family  Bipyridilium
•  mesotrione (Callisto)
Rate  0.188 lb ai/A (6 fl oz/A)
Time  Apply to dormant rhubarb before spring green-up.
Remarks  Provides both preemergence and postemergence weed control. Add crop oil concentrate at 1% v/v or nonionic surfactant at 0.25% to spray solution if weeds have emerged.
Caution  Applying Callisto to nondormant rhubarb may result in a temporary bleaching. Rain or irrigation after application may increase risk of injury to emerging rhubarb. Preharvest interval is 21 days. Do not exceed 6 fl oz/A or one application per year.
Site of action  Group 28: inhibits 4-hydroxyphenylpyruvatedioxygenase (4-HPPD)
Chemical family  Triketone
•  napropamide (Devrinol 50DF)
Rate  4 lb ai/A (8 lb/A)
Time  Apply to weed-free soil surface in winter to dormant rhubarb, before weeds begin to germinate. Inhibits root growth.
Site of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Acetamide
•  pronamide (Kerb)
Oregon and Washington only
Rate  1 to 2 lb ai/A (2 to 4 lb/A)
Time  Apply in fall or winter to established rhubarb for grass and chickweed control. Results are best if soil is below 55°F and rain or irrigation follows application.
Remarks  Requires moisture from overhead irrigation or rain to activate. Inhibits root growth. Poorly controls weeds in the Asteraceae (Composite) family.
Caution  A restricted-use herbicide. Do not apply to newly transplanted rhubarb or to rhubarb that is actively growing. Preharvest interval is 38 days. Do not exceed 2 lb ai/A per year.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Benzamide
•  S-metolachlor (Dual Magnum)
Rate  0.63 to 1.27 lb ai/A (0.66 to 1.33 pints/A)
Time  Broadcast on soil surface before crop emerges.
Remarks  Do not exceed 1.33 pints/A or one application per crop. Use lower rates on light-texture soils, higher rates on fine-texture soils. Dual Magnum will not control emerged weeds.
Caution   Preharvest interval is 62 days.
Site of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Chloroacetamide
•  sethoxydim (Poast)
Rate  0.28 lb ai/A (1.5 pints/A)
Time  Apply at optimum growth stage listed on 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, heat, or low fertility. Resistant grasses include annual bluegrass and all fine fescues, but quackgrass can be suppressed.
Caution  Do not mix or apply with any other pesticide, additive, or fertilizer except as specified on label. Preharvest interval is 30 days. 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 or Prism)
Oregon and Washington only
Rate  0.094 to 0.125 lb ai/A (6 to 8 oz/A Select)
Time  Apply to actively growing grass weeds, including annual bluegrass, at growth stages on label.
Remarks  Read label carefully for adjuvant instructions; note effects of rain within 1 hr of applying other pesticides and of cultivation.
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

Tomatoes, Peppers, and Eggplants
Ed Peachey
Revised November 17, 2008
TOMATOES, PEPPERS, AND EGGPLANTS—Pretransplant, Preemergence, or Postdirected
•  carfentrazone (Aim EC)
transplants only
Rate  Up to 0.031 lb ai/A (2 fl oz Aim EC)
Time  Apply up to 1 day before transplanting.
Remarks  Tank-mixes with other herbicides increase spectrum of control. Apply to actively growing weeds not more than 4 inches tall or rosettes 3 inches in diameter. Contact activity only. Coverage is essential for good control.
Caution  Do not exceed 0.031 lb ai/A (2 fl oz Aim EC) per crop season. 
Site of action  Group 14: protoporphyrinogen oxidase inhibitor
Chemical family Triazinone
•  S-metolachlor (Dual Magnum, Charger Basic, or Brawl)
supplemental label; tomatoes only
Rate  0.95 to 1.9 lb ai/A (1 to 2 pints/A) depending on soil texture and organic matter content
Time  Pretransplant incorporated, pretransplant on the surface, or postdirected to transplanted tomatoes at least 4 inches tall.
Remarks  If applied pretransplant, incorporate but to less than the depth of transplanting. Postdirected applications to transplanted tomatoes should be after the first irrigation or settling rain.
Caution  Do not apply to varieties or cultivars with unknown tolerance to Dual Magnum. Dual Magnum may damage transplants weakened for any reason. Do not plant under wet, cool, or unfavorable growing conditions. Preharvest interval is 90 days.
Site of action  Group 15: inhibits very long-chain fatty acid synthesis
Chemical family  Chloroacetamide
•  S-metolachlor (Dual Magnum)
transplanted bell peppers, Oregon only
Rate  Before transplanting: 0.48 to 0.96 lb ai/A (0.5 to 1 pint/A Dual Magnum); after transplanting: 0.96 to 1.6 lb ai/A (1 to 1.67 pints/A Dual Magnum). Use lower rates on coarse soil and higher rates on fine-texture soil. In most Willamette Valley soils, if used according to label, 1 pint/A gives acceptable weed control with minimal phytotoxicity concerns.
Time  Before and after transplanting (do not incorporate).
Remarks  Special local needs label OR-070004. Transplanted bell peppers are very tolerant to over-the-top broadcast applications of S-metolachlor. Do not add adjuvants of any kind. Will not control emerged weeds, so till 2 to 3 days before applying to destroy weeds that may have emerged. Weed control is best if applied after transplanting and about 0.5 inch of irrigation water is applied shortly after transplanting (up to 2 days). Excessive water will lessen weed control.
Caution  Ensure that S-metolachlor-treated soil is not concentrated near bell pepper roots during transplanting, by minimizing the amount of S-metolachlor-treated soil allowed into the furrow during planting. Muck soils (more than 20% organic matter) normally require the higher rate (1 pint/A); however, weed control may be reduced on muck soils. S-metolachlor may injure crops if plant roots directly contact treated soil. Apply only once per crop; do not exceed 1 pint/A. Do not apply and incorporate S-metolachlor before transplanting. Preplant-incorporated applications may injure crop. Do not apply to direct-seeded crops. Tank-mixing with other herbicides may increase the chance of crop injury. Preharvest interval is 60 days.
Site of action  Group 15: inhibits very long-chain fatty acid synthesis
Chemical family  Chloroacetamide
•  trifluralin (Treflan)
Rate  0.5 to 1 lb ai/A (1 to 2 pints/A) depending on soil type and crop
Time  Apply before transplanting peppers and before or after transplanting tomatoes or eggplant. Incorporate within 24 hr by cross-disking or by using a power take-off (PTO) rotary tiller. 
Remarks  Spray only once and avoid overlaps. Use lower rates on light or coarse soils low in organic matter. Consult label for planting crops within 12 mo. Direct sprays to soil beneath transplants if applying postemergence. Inhibits mitosis, primarily in shoots.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
• pendimethalin (Prowl H2O only)
Rate  0.475 to 1.43 lb ai/A (1 to 3 pints/A) depending on soil type.
Time  Preplant incorporate before transplanting; preplant surface before transplanting; or postdirected application to transplanted or established direct-seeded tomatoes and peppers. 
Remarks  Spray only once and avoid overlaps. Use lower rates on light or coarse soils low in organic matter. Consult label for planting crops within 12 mo. Direct sprays to soil beneath transplants if applying postemergence. Inhibits mitosis, primarily in shoots. Preharvest interval is 70 days.
Caution  Do not apply to direct-seeded tomatoes or over the top of tomatoes or peppers, as injury will be severe. Consult crop injury disclaimer on label before using.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
•  napropamide (Devrinol)
Rate  1 to 2 lb ai/A (2 to 4 lb/A)
Time  Apply and incorporate uniformly 1 to 2 inches deep before transplanting. Use lower rates on light, sandy, or coarse soils.
Remarks  After harvest, plow deeply with moldboard or disk plow before planting succeeding crops. Inhibits seedling roots.
Site of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Acetamide
•  halosulfuron (Sandea)
pretransplant in tomatoes only, including under plastic mulch
Rate  0.375 to 0.75 oz ai/A (0.5 to 1 oz/A)
Time  Pretransplant applied to bare ground with transplanting 7 days later.
Remarks  Controls nutsedge and may be used under plastic mulch. Make a second postemergence application if nutsedge breaks through the plastic.
Caution  Sandea-treated soil in transplant hole may injure crop. Note crop rotation intervals.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  DCPA (Dacthal)
tomatoes only
Rate  4.5 to 10.5 lb ai/A (6 to 14 lb/A)
Time  Apply 4 to 6 wk after transplanting to moist, weed-free soil; apply more water to activate.
Remarks  Performs poorly in western Oregon and Washington. Consult label for planting sensitive crops within 12 mo. Results can be improved with overhead irrigation immediately after spraying. Inhibits mitosis.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Phthalic acid
•  clomazone (Command 3ME)
peppers only, but not on banana peppers
Rate  0.25 to 1 lb ai/A (0.66 to 2.66 pints/A). Use lower rates on coarse soil, higher rates on fine soils.
Time  Preemergent soil-applied before transplanting.
Remarks  Place roots below the chemical barrier when planting. Do not use on banana peppers.
Caution  Clomazone has a residual or carryover of up to 16 mo; therefore, consult label for rotational crops before applying. Do not apply next to sensitive crops when there is potential for drift. The microencapsulated (ME) formulation is designed to minimize drift and injury to adjacent fields and sites.
Site of action  Group 13: inhibits DOXP synthase
Chemical family  Isoxazolidinone
TOMATOES, PEPPERS, AND EGGPLANTS—Postemergence
•  metribuzin (Sencor)
tomatoes only
Rate  0.25 to 0.5 lb ai/A (0.5 to 1 pint/A)
Time  Preplant incorporate before transplanting; or apply postemergence as a single treatment or a split application, with at least a 14-day interval, at 0.25 to 0.37 lb ai/A to tomatoes with at least five to six true leaves but before weeds are 1 inch tall.
Remarks  Use lower rates on soils with 0.5 to 2% organic matter, but do not use on soils with less than 0.5% organic matter. Inhibits photosynthesis.
Caution  Do not use surfactant or tank-mix with other pesticides. Do not apply within 24 hr of other pesticide applications. Preharvest interval is 7 days. Do not apply within 3 days after cool, wet, or cloudy weather. Do not exceed 1 lb ai/A per season. Carefully note other precautions on label.
Site of action  Group 5: photosystem II inhibitor
Chemical family  Triazinone
•  metribuzin (Lexone or Sencor)
established tomatoes only
Rate  Directed spray at 0.5 to 1 lb ai/A
Time  Apply as a single treatment or a split application with at least a 14-day interval when weed pressure is intense or in fields with hard-to-control weeds.
Caution  Do not exceed 1 lb ai/A per season. Note other precautions above and on label.
Site of action  Group 5: photosystem II inhibitor
Chemical family  Triazinone
•  rimsulfuron (Matrix)
field-grown tomatoes only
Rate  0.25 to 0.5 oz ai/A (1 to 2 oz/A) postemergence
Time  Apply when weeds are less than 1 inch tall or wide and crop is at the cotyledon stage.
Remarks  Use a nonionic surfactant at 0.25% v/v. Sequential applications 7 to 14 days apart may improve black nightshade control.  Tomato varieties may differ in tolerance to rimsulfuron; apply to a small test area before treating whole fields.
Caution  Using adjuvants at more than 0.25% v/v may result in temporary chlorosis. Consult labels for rotational intervals. Preharvest interval is 45 days.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  halosulfuron (Sandea)
broadcast only in tomato; row middles and furrows for peppers and eggplants
Rate  0.375 to 0.75 oz ai/A (0.5 to 1 oz/A)
Time  Apply broadcast to actively growing transplanted tomatoes with four leaves or more, 14 days or more after transplanting, but before first bloom. Apply to row middles or furrows only in direct-seeded peppers and eggplants, avoiding herbicide contact with the planted crop. 
Remarks  Will not suppress or control nightshade species. 
Caution  Observe crop rotation restrictions carefully.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  sethoxydim (Poast)
Rate  0.28 lb ai/A (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 heat, or low fertility. Resistant grasses include annual bluegrass and all fine fescues; quackgrass can be suppressed.
Caution  Preharvest interval is 20 days. Do not exceed 4.5 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 (Prism or Select)
Rate  For tomatoes, 0.094 to 0.188 lb ai/A (6 to 12 oz/A Select); for peppers and eggplants, 0.094 to 0.125 lb ai/A (6 to 8 oz/A Select). Also depends on weed growth stage.
Time  Apply to actively growing grass weeds, including annual bluegrass, at growth stage as on label.
Remarks  Consult labels for maximum rates per application and season. Read label carefully for adjuvant instructions and for information about effects of rain within 1 hr, applications of other pesticides, and cultivation. Preharvest interval is 20 days.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione
•  paraquat (Gramoxone Inteon, 2 lb paraquat cation/gal)
Rate  Preplant and preemergence: 0.43 to 0.68 lb ai/A cation (1.7 to 2.7 pints/A Inteon). Postemergence directed: 0.43 lb ai/A cation (1.7 pints/A Inteon).
Time  Apply as a directed spray to emerged weeds between rows after crop is established.
Caution  Do not exceed three applications per season. Preharvest interval is 30 days. Do not graze animals.
Site of action  Group 22: photosystem I electron diversion
Chemical family  Bipyridilium

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