Annual Broadleaf Weeds

Preplant surface, preplant incorporated, or preemergence

metribuzin (several trade names)

Rate 0.1875 to 0.375 lb ai/a (4 to 8 oz/a of a 75% DF product)

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 if seeds are planted 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

saflufenacil (Sharpen)

Rate 0.022 to 0.044 lb ai/a (1.0 to 2.0 oz/a Sharpen)

Time Apply early preplant, preplant incorporated or preemergence for limited residual broadleaf weed control.

Remarks Sharpen controls mainly broadleaf weeds. Methylated seed oil (MSO) or crop oil concentrate (COC), at 1% v/v + ammonium sulfate (AMS) at 8.5 to 17 lb/100 gal of water, are required for satisfactory control of emerged weeds. An early preplant application of Sharpen at 1.0 to 2.0 oz/a can be made prior to a PPI or preemergence application. Sequential applications must be at least 30 days apart.

Caution Do not substitute a nonionic surfactant for MSO or COC as control of emerged weeds will suffer. Do not exceed 2.0 oz/a during the cropping season. Do not apply when the peas have reached the cracking stage, or after emergence, because severe crop injury will occur. Legume forage may be fed or grazed 65 or more days after application.

Site of action Group 14: protoporphyrinogen oxidase (PPO) inhibitor

Chemical family Uracil

Postemergence

bentazon (Basagran or other trade names)

Rate 0.5 to 1 lb ai/a (1 to 2 pints/a Basagran)

Time Peas tolerate bentazon after 3-leaf (or 4-node) stage. Apply to small, actively growing annual broadleaf weeds as per label. Do not apply to peas in bloom. 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 inadequate. See label for adjuvant rates. 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 7 days after applying.

Site of action Group 6: photosystem II inhibitor

Chemical family Benzothiadiazole

imazamox (Raptor or other trade names)

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 peas, always apply 6 to 16 oz/a Basagran to minimize potential for crop response. Only one application of Raptor may be made during the season.

Caution Read and observe all precautions on the label to ensure maximum crop safety. Consult label restrictions regarding planting subsequent crops.

Site of action Group 2: acetolactate synthase (ALS) inhibitor

Chemical family Imidazolinone

imazamox + bentazon (Varisto)

Rate 0.023 to 0.031 lb ae/a imazamox + 0.5 to 0.66 lb ae/a bentazon (16 to 21 oz/a Varisto)

Time Apply to dry peas with at least three pairs of leaves before blooming. Do not apply within 30 days of harvest.

Remarks Apply with nonionic surfactant at 1 quart/100 gal. Weed control may be improved by adding 12 to 15 lb ammonium sulfate or 2.5 gal liquid fertilizer (28% or 32%) per 100 gal of spray solution. Only one application may be made per season.

Caution Read and observe all precautions on the label to ensure maximum crop safety. Consult label restrictions regarding planting subsequent crops.

Site of action (imazamox) Group 2: acetolactate synthase (ALS) inhibitor; (bentazon) Group 6: photosystem II inhibitor

Chemical family (imazamox) Imidazolinone; (bentazon) Benzothiadiazole

MCPA sodium salt or dimethylamine salt (Chiptox, MCPA amine 4, or other trade names)

Rate 0.125 to 0.375 lb ae/a (0.5 to 1.5 pints/a Chiptox; 0.25 to 0.75 pints/a MCPA amine 4). 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 Do not apply when peas are blooming. Peas may show slight injury, but usually recover a few days after treatment. Not recommended for use in western Washington.

Caution Do not apply when the temperature is expected to reach 90°F within the next 24 hours. 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

metribuzin (several trade names)

Rate 0.125 to 0.25 lb ai/a (2.6 to 5.3 oz/a of a 75% 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 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