Peas (Dry)
Dan Ball
Revised November 26, 2008

PEAS, DRY—Annual Grass and Broadleaf Weeds
Preplant incorporated
•  trifluralin (Treflan and others)
Rate  0.5 to 0.75 lb ai/A
Time  Apply preplant and incorporate. May be fall-applied.
Remarks  Incorporate thoroughly 2 to 3 inches deep right after applying. Use lower rate on coarse soils. Controls some broadleaf weeds; weak on nightshade, mustard, and mayweed.
Caution  Consult label about planting subsequent crops. Trifluralin may injure stressed crop seedlings.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
•  ethalfluralin (Sonalan)
Rate  0.56 to 0.75 lb ai/A (1.5 to 2 pints/A Sonalan)
Time  Apply preplant and incorporate by following label instructions.
Caution  Do not exceed labeled rates or crop may be injured. Do not graze or plant forage crop in treated soil or cut for hay or silage. For use only in dry peas.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
•  pendimethalin (Prowl 3.3EC, Stealth, Prowl H2O, and others)
Rate  0.5 to 1.5 lb ai/A (1.2 to 3.6 pints/A Prowl) or 0.7 to 1.4 lb ai/A (1.5 to 3 pints/A Prowl H2O). Use the lower rate on coarse soils, the higher rate on fine soils.
Time  Apply up to 60 days preplant and incorporate by following label instructions.
Remarks  Incorporate thoroughly 1 to 2 inches deep. Apply in at least 10 gal/A water or in 20 gal/A or more liquid fertilizer. Also controls several broadleaf weed species.
Caution  Do not apply to pea or lentil forage, silage, hay, or straw grown for feed.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
•  triallate (Far-Go)
Rate  1.25 to 1.5 lb ai/A
Time  Apply preplant or postplant and incorporate.
Remarks  Incorporate thoroughly 1 to 2 inches deep. Do not graze treated areas. To control wild oats only.
Site of action  Group 8: lipid synthesis inhibitor but not an ACCase inhibitor
Chemical family  Thiocarbamate
•  trifluralin + triallate (Buckle)
Rate  0.3 to 0.38 lb ai/A trifluralin + 1 to 1.25 lb ai/A triallate as Buckle (10 to 12.5 lb/A Buckle)
Time  Apply preplant and incorporate.
Remarks  Buckle is a granular formulation of both herbicides. Incorporate thoroughly 1 to 2 inches deep immediately after application. Use the lower trifluralin rate for coarse soils. See remarks in trifluralin entry in this section. Do not use foliage from treated peas for feed or forage.
Site of  action  (trifluralin) Group 3: microtubule assembly inhibitor; (triallate) Group 8: lipid synthesis inhibitor but not an ACCase inhibitor
Chemical family  (trifluralin) dinitroaniline; (triallate) thiocarbamate
•  imazethapyr (Pursuit or Pursuit DG)
Rate  0.047 lb ai/A (3 oz/A of Pursuit or 1.08 oz/A of Pursuit DG)
Time  Apply preplant and incorporate within 30 days before planting. Do not incorporate deeper than 3 inches.
Remarks  Registered in Oregon, Washington, Idaho, and Montana only.
Caution  Do not apply more than once per year. Preharvest interval is 60 days. Study label regarding planting subsequent crops.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
•  sulfentrazone (Spartan 4F)
Rate  0.07 to 0.25 lb ai/A (2.25 to 8 fl oz/A Spartan 4F)
Time  Apply after planting but before crop germinates.
Remarks  See current label for appropriate use areas. Use rate dependent on soil texture and organic matter. Consult label for use rates for specific soil type. PNW data suggest that use rates above 4.5 fl oz/A may cause injury to dry peas.
Caution  Do not exceed 8 fl oz/A per year. Preharvest interval is 60 days. See label before planting subsequent crops.
Site of action  Group 14: protoporphyrinogen oxidase inhibitor
Chemical family  Triazinone
Preemergence
•  metolachlor (Dual Magnum or Dual II Magnum)
Rate  1.5 to 3 lb ai/A
Time  Apply preemergence only.
Remarks  Application rate depends on soil type and organic matter content.
Caution  Preharvest interval for hay is 120 days.
Site of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Chloroacetamide
•  imazethapyr (Pursuit or Pursuit DG)
Rate  0.047 lb ai/A (3 oz/A of Pursuit or 1.08 oz/A Pursuit DG)
Time  Apply after planting but before crop emerges.
Remarks  Registered in Oregon, Washington, Idaho, and Montana only. See current label for appropriate use areas.
Caution  Do not apply more than once per year. Preharvest interval is 60 days. See label before planting subsequent crops.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
PEAS, DRY—Annual and Perennial Grass Weeds
Postemergence
•  sethoxydim (Poast)
Rate  0.19 to 0.48 lb ai/A (1 to 2.5 pints/A Poast)
Time  Apply to actively growing grasses listed on label. Add 2 pints/A nonphytotoxic crop oil concentrate for ground application to improve leaf penetration.
Remarks  Ask knowledgeable people about susceptible grasses in your area. Control may be erratic if grasses are stressed from lack of vigor, drought, or high temperature. Fine fescues and annual bluegrass resist treatment; quackgrass is suppressed.
Caution  Preharvest interval is 30 days. Do not exceed 4 pints/A product per year. Do not mix or apply with any other pesticide, additive, or fertilizer except as directed on the label.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione
•  quizalofop P-ethyl  (Assure II or Targa)
Rate  0.04 to 0.08 lb ai/A (6 to 12 fl oz/A Assure II)
Time  After grasses emerge. See label for details.
Remarks  Controls both annual and perennial grasses. Always use either a nonionic surfactant at 1 quart/100 gal or a petroleum-based crop oil at 1 gal/100 gal.
Caution  Do not exceed 14 fl oz/A per season. Preharvest interval is 60 days. No grazing or feeding restrictions.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Aryloxyphenoxy propionate
•  clethodim (Select, Intensity One)
Rate  0.063 to 0.078 lb ai/A (4 to 5 fl oz/A Select 2EC)
Time  After grasses emerge. See label for details.
Remarks  Controls both annual and perennial grasses. Always use a petroleum-based crop oil at 1 gal/100 gal.
Caution  Do not exceed 5 fl oz/A per season. Preharvest interval is 75 days. Do not graze. Do not apply after crop begins bolting. Applying during bloom period may injure crop.
Site of action  Group 1: acetyl CoA Carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione

PEAS, DRY—Annual Broadleaf Weeds
Preemergence
•  metribuzin (several products)
Rate  0.1875 to 0.375 lb ai/A (4 to 8 oz DF product/A). 
Time  Apply before or after planting but before crop emerges.
Remarks  Rain or mechanical incorporation is needed to suppress weeds. Under dry conditions, incorporate 1 to 2 inches. Apply in 10 gal/A or more of water for ground equipment or 5 gal/A or more for aerial spray equipment.
Caution  Do not apply on seedings less than 2 inches deep. Do not use on clay knobs or poorly covered subsoils. Do not use on coarse soils or soils with less than 1.5% organic matter. Heavy rain after application may injure crop. This treatment may cause some chlorosis or minor necrosis. Preharvest interval is 50 days for dry peas, 120 days for hay.
Site of action  Group 5:  photosystem II inhibitor
Chemical family  Triazinone
Postemergence
•  MCPA amine (Chiptox and others)
Rate  0.125 to 0.375 lb ae/A. Lower the rate as temperature increases.
Time  Apply when peas are 4 to 6 inches tall and weeds are less than 2 inches wide or 3 inches high.
Remarks  Not recommended for use in western Washington.
Caution  Do not apply when the temperature is expected to reach 90°F within the next 24 hr. Do not permit MCPA to drift off target. Do not graze or feed.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  bentazon (Basagran and others)
Rate  0.5 to 1 lb ai/A (1 to 2 pints/A Basagran)
Time  Peas tolerate bentazon after three-leaf (or four-node) stage. Apply to small, actively growing annual broadleaf weeds as per label. For Canada thistle and yellow nutsedge, use higher rate and apply twice, 7 to 10 days apart.
Remarks  Avoid applying bentazon during prolonged cold weather; weed control may be nullified. One quart/A (by ground) or 1 pint/A (by air) of crop oil concentrate improves control. Crop may show temporary symptoms under certain environmental conditions. Preharvest interval is 30 days. Do not exceed 2 lb ai/A per year. Do not cultivate within 5 days before or after applying.
Site of action  Group 6: photosystem II inhibitor
Chemical family  Benzothiadiazole
•  imazamox (Raptor)
Rate  0.031 lb ai/A (4 oz/A Raptor)
Time  Apply to dry peas with at least three pairs of leaves before blooming.
Remarks  Apply with nonionic surfactant at 1 quart/100 gal. In dry pea, apply 6 to16 oz/A Basagran for additional crop safety.
Caution  Read and observe all precautions on the label to ensure maximum crop safety.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
•  metribuzin (Sencor, Tricor DF, and others)
Rate  0.125 to 0.25 lb ai/A (2 to 5.3 oz/A product)
Time  Apply only once per season to susceptible broadleaf weeds less than 2 inches tall or wide.
Remarks  Temporary chlorosis of the crop may occur, particularly under moist conditions or if a postemergence application follows a preemergence metribuzin herbicide application. Weed control may be reduced if dry conditions persist after treatment. 
Caution  Do not use on clay knobs or poorly covered subsoils. Do not use on coarse soils or soils with less than 1.5% organic matter. Heavy rain after application may injure crop. Preharvest interval is 50 days for dry peas, 40 days for hay. Do not exceed 0.5 lb ai/A metribuzin per crop year.
Site of action  Group 5: photosystem II inhibitor
Chemical family  Triazinone
PEAS, DRY—Canada Thistle and Annual Broadleaf Weeds
•  MCPB (Thistrol)
Rate  0.5 to 1.5 lb ae/A. Use higher rate during cool weather.
Time  Apply when peas have six to twelve nodes, but before flower buds form, and Canada thistle is 4 to 10 inches tall.
Remarks  Canada thistle is only suppressed and usually regrows.
Caution  Do not permit MCPB to drift off target. Do not feed peas or vines to livestock. Do not apply if temperature is expected to exceed 85°F within the next 24 hr. Do not spray peas under moisture stress.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid

Peas (Winter)
Dan Ball
Revised  November 26, 2008
PEAS, WINTER—Winter Annual Weeds
•  pronamide (Kerb)
Rate  0.75 to 1.5 lb ai/A (1.5 to 3 lb/A Kerb)
Time  November to January, when peas are in the second node (2 to 3 inches).
Remarks  Ground sprayer only; apply in at least 20 gal/A water. If weeds are larger than 3 inches, use the higher rate. Controls henbit that germinates after application. 
Caution  A restricted-use herbicide. Protective measures required for applicator. Do not feed or allow animals to graze vines after treatment.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Benzamide
•  bentazon (Basagran)
Rate  0.5 to 1 lb ai/A (1 to 2 pints/A Basagran)
Time  Peas tolerate bentazon after three-leaf (or four-node) stage. Apply to small, actively growing annual broadleaf weeds as per label. For Canada thistle and yellow nutsedge, use the higher rate and apply two times, 7 to 10 days apart.
Remarks  Avoid applying bentazon during prolonged cold weather; weed control may be nullified. Do not apply if temperatures exceed 80°F. Using 1 quart/A of crop oil concentrate by ground or 1 pint/A by air improves weed control. Temporary injury symptoms may occur on the crop under certain environmental conditions. Preharvest interval is 30 days. Do not exceed 2 lb ai/A/yr. Do not cultivate within 5 days before or after applying bentazon.
Site of action  Group 6: photosystem II inhibitor
Chemical family  Benzothiadiazole
•  metribuzin (several products)
Rate  0.1875 to 0.25 lb ai/A (3 to 5.3 oz/A of a DF product)
Time  Apply only once per season to susceptible broadleaf weeds less than 2 inches tall or wide.
Remarks  Temporary chlorosis of the crop may occur, particularly under moist conditions or if a postemergence application follows a preemergence metribuzin herbicide application. Weed control may be reduced if dry conditions persist after treatment.
Caution  Do not use on clay knobs or poorly covered subsoils. Do not use on coarse soils or soils with less than 1.5% organic matter. Heavy rain after application may injure crop. Preharvest interval is 50 days for winter peas, 120 days for hay. Do not exceed 0.5 lb ai/A metribuzin per crop year.
Site of action  Group 5: photosystem II inhibitor
Chemical family  Triazinone
•  sethoxydim (Poast)
Rate  0.29 to 0.48 lb ai/A (1.5 to 2.5 pints/A Poast)
Remarks  Apply to actively growing grasses listed on label. Add 2 pints/A of a nonphytotoxic crop oil concentrate for ground application to improve penetration into leaves. Ask knowledgeable people about susceptible grasses in your area.
Caution  Control may be erratic on grasses stressed by lack of vigor, drought, high temperature, low fertility, or grass stage of growth. Fine fescues and annual bluegrass resist treatment; quackgrass is suppressed. Preharvest interval is 30 days. Do not exceed 4 pints/A product per year. Do not mix or apply with any other pesticide, additive, or fertilizer except as directed on the label.
Site of action  Group 1: acetyl CoA Carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione
PEAS, WINTER—Harvest Aid
•  paraquat (Gramoxone Inteon)
Rate  0.3 to 0.5 lb ai/A (1.2 to 2 pints/A Gramoxone Inteon)
Time  Use with a nonionic surfactant, crop oil concentrate, or methylated seed oil. Apply when crop is mature: i.e., at least 80% of pods are yellowing and mostly ripe, and no more than 40% (bush-type peas) or 30% (vine-type peas) of leaves are still green.
Remarks  Split applications permitted. Do not exceed two applications per season.
Caution  A restricted-use herbicide. Do not allow to drift from target site.
Site of action  Group 22: photosystem I electron diversion
Chemical family  Bipyridilium
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