Winter Annual Weeds

Preplant incorporated or preemergence

sulfentrazone (Spartan 4F)

Rate 0.07 to 0.25 lb ai/A (2.25 to 8 oz/A Spartan 4F)

Time Apply preplant incorporated (spring only) or early preplant in the fall or spring up to 3 days after planting as a preemergence application.

Remarks See current label for appropriate use areas. Use rate depends on soil texture and organic matter. Consult label for use rates for specific soil type. PNW data suggest that use rates above 4.5 oz/A may cause injury to dry peas.

Caution Do not exceed 8 oz/A per 12-month period. See label before planting subsequent crops. Do not incorporate to depths greater than 2 inches. Do not apply after crop emerges, or if seedlings are near soil surface. Do not apply to frozen soil.

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

Chemical family Aryl triazinone

Preplant surface or preemergence

sulfentrazone + carfentrazone (Spartan Charge)

Rate 0.074 to 0.251 lb ai/A sulfentrazone + 0.008 to 0.028 lb ai/A carfentrazone (3.0 to 10.2 oz/A Spartan Charge)

Time Apply fall or spring as preplant or preemergence.

Remarks Consult label to determine rate for soil pH, percentage of organic matter, and texture. Consult label for specific crop rotation restrictions.

Caution Do not exceed 0.28 lb ai (10.2 oz) Spartan Charge per 12-month period. Do not apply after crop emerges or if seedlings are near soil surface. Do not apply on sandy soils with less than 1% organic matter. Do not apply to frozen soil. Do not incorporate as this can destroy the herbicide barrier.

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

Chemical family Aryl triazinone

sulfentrazone + S-metolachlor (Spartan Elite)

Rate 0.1 to 0.2 lb ai/A sulfentrazone + 0.94 to 1.88 lb ai/A S-metolachlor (19 to 38 oz/A Spartan Elite)

Time Apply fall or spring as preplant or preemergence.

Remarks Consult label to determine rate for soil's percentage of organic matter and texture. Consult label for specific crop rotation restrictions.

Caution Do not apply to coarse-textured soils with less than 1% organic matter. Adequate rainfall is required for herbicide activation from rainfall. If activating moisture is not received within 7 to 10 days after application, a shallow incorporation may be needed to obtain adequate weed control. Do not incorporate to depths greater than 2 inches. Do not apply to frozen soils. Do not use for forage within 60 days after an application. Do not cut for hay within 120 days after application.

Site of action (sulfentrazone) Group 14: protoporphyrinogen oxidase inhibitor; (S-metolachlor) Group 15: inhibits very long chain fatty acid synthesis

Chemical family (sulfentrazone) Aryl triazinone; (S-metolachlor) Chloroacetamide

Preemergence

diuron (Diuron 4L, others)

Western Oregon only

Rate 1.2 to 2.6 lb ai/A (1.2 to 2.6 quart/A Diuron), depending on soil type

Time Apply as soon as possible after planting and before crop emerges.

Remarks Diuron will only control certain weeds, consult label. Do not apply on sand, sandy loam, or gravelly soils. Aerial application is prohibited.

Caution Crop injury may result if soil organic matter is less than 1%. Consult label for other restrictions.

Site of action Group 7: Photosystem II inhibitor

Chemical family Urea

Postemergence

bentazon (Basagran or Basagran 5L)

Rate 0.5 to 1 lb ai/A (1 to 2 pints/A Basagran); 0.75 to 1 lb ai/A (1.2 to 1.6 pints/A Basagran 5L)

Time Peas tolerate bentazon after 3-leaf (or 4-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 inadequate. Do not apply if temperatures exceed 80°F. See label for adjuvant rates. Temporary injury symptoms may occur 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 bentazon.

Site of action Group 6: photosystem II inhibitor

Chemical family Benzothiadiazole

metribuzin (several product names)

Rate 0.1875 to 0.25 lb ai/A (4 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, and before peas are 6 inches tall.

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

pronamide (Kerb)

Rate 0.75 to 1.5 lb ai/A (2 to 3.5 pints/A Kerb SC)

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.

Caution A restricted-use herbicide. Protective measures required for applicator. Do not feed, or allow animals to graze vines, after treatment. Do not make more than one treatment per season.

Site of action Group 3: microtubule assembly inhibitor

Chemical family Benzamide

quizalofop P-ethyl (Assure II or Targa)

Rate 0.04 to 0.08 lb ai/A (6 to 12 oz/A Assure II or Targa)

Time After grasses emerge. See label for details.

Remarks Controls 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 oz/A per season. Preharvest interval is 60 days. Do not graze livestock in treated areas or feed forage, hay, or straw from treated areas.

Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor

Chemical family Aryloxyphenoxypropionate

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 non-phytotoxic 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