Postemergence

bentazon (Basagran)

Rate 0.75 to 1 lb ai/a (1.5 to 2 pints/a)

Time Apply as pea tolerance increases, as waxes develop on leaf surfaces.

Remarks Apply to peas having at least three pairs of leaves (four nodes) but prior to flowering. Temporary foliar injury may occur under conditions that result in the cuticle of pea leaves allowing too much herbicide to be absorbed, including temperatures over 80°F, or application on a sunny day immediately after several cloudy days. Small, newly emerged broadleaf weeds can be controlled in early spring, at cool temperatures (75°F day, 55°F night), by adding a highly refined nonphytotoxic oil concentrate (see label). Do not apply to peas under stress from root rot.

Caution Do not tank mix with spray additives or pesticides except MCPA and MCPB (without crop oil). Preharvest interval is 30 days. Do not exceed 2 lb ai/a (4 pints/a) per season.

Site of action Group 6: photosystem II inhibitor

Chemical family Benzothiadiazole

clethodim (Select Max and other trade names)

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.

Caution Do not exceed 32 fl oz/a per year. Allow at least 14 days between applications. Preharvest interval is 21 days.

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

Chemical family Cyclohexanedione

halosulfuron-methyl (Sandea)

Rate 0.023 to 0.046 lb ai/a (0.5 to 1 oz/a)

Time Postemergence

Remarks Apply as a directed spray when peas have 2 to 4 trifoliate leaves and before flowering. Directed sprays are recommended to limit crop injury. Make one broadcast application with ground equipment in a minimum of 15 gallons of water per acre. Use a nonionic surfactant at 0.25% (v/v) with postemergence applications. Not all pea varieties have been tested for tolerance. Under adverse growing conditions, maturity of the treated crop may be delayed, affecting harvest date, yield, and quality. For untested varieties, a small area of the field should be sprayed to determine potential sensitivity to its use. See label for significant crop rotation restrictions for this herbicide.

Caution Application of halosulfuron may cause significant, temporary stunting and delay maturity of peas resulting in delayed harvest. This product is available to the end-user/grower solely to the extent that the benefit and utility, in the sole opinion of the end-user/grower, outweigh the extent of potential injury associated with the use of this product. Due to the risk of crop damage, all such use is at the end-use/grower's risk.

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

Chemical family Sulfonylurea

imazamox (Raptor)

Rate 0.023 lb ae/a (3 fl.oz/a)

Time Postemergence

Remarks Make one application when peas are at least 3 inches tall, but before 5 nodes and before flowering. The use of trifluralin before imazamox treatment may increase the likelihood and severity of crop injury. Use a nonionic surfactant at 0.25% (v/v) with postemergence applications. For enhanced grass activity, add crop oil concentrate at 1% (v/v) instead of nonionic surfactant. Mixing with bentazon may lessen potential for crop injury. See label for significant crop rotation restrictions for this herbicide.

Caution Use of this product may lead to crop injury, loss, or damage. BASF recommends that the user and/or grower test this product to determine its suitability for such intended use. Reduced crop growth, quality and yield, temporary yellowing and/or delayed maturity may result from an imazamox application to pea. Because crop maturity may be delayed, timing of harvest may need to be adjusted accordingly. Do not apply imazamox if planting is delayed and a chance of frost before maturity is likely. Growers should check with the seed company regarding the safety of imazamox to their variety.

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

Chemical family Imidazolinone

imazamox+ bentazon (Varisto)

Rate 0.023 lb ai/a imazamox and 0.5 lb ai/a bentazon (1 pint/a)

Time Apply as pea tolerance increases, as waxes develop on leaf surfaces.

Remarks There are no University data for use of this product in the PNW. Apply to peas at least 3-inches tall but prior to 5 nodes before flowering. Temporary foliar injury may occur under conditions that result in the cuticle of pea leaves allowing too much herbicide to be absorbed, including temperatures over 80°F, or application on a sunny day immediately after several cloudy days. Avoid applying this product during prolonged periods of cold weather (day temperature below 75°F and night temperature below 55°F for 2 to 5 days) because weed control may be reduced. An adjuvant must be used with this product, although adjuvants with or without nitrogen fertilizer may increase injury and reduce yield. Do not apply to peas under stress from root rot. See label for significant crop rotation restrictions for this herbicide.

Caution In-furrow treatments of insecticides or nematicides or use of trifluralin may predispose English pea to injury from this product. Preharvest interval is 10 days. Do not apply more than once per season.

Site of action Group 6: photosystem II inhibitor

Chemical family Benzothiadiazole

MCPA (several trade names)

Rate 0.125 to 0.375 lb ae/a (0.25 to 0.75 pint/a)

Time Apply postemergence to control small broadleaf weeds or prevent flowering in larger weeds such as nightshade when peas exceed 4 to 6 inches.

Remarks Adjust rates for expected temperatures; see label.

Caution Do not apply if temperature may exceed 90°F within 24 hr. Maintain spray pressure below 40 psi to minimize drift from target field. Do not feed treated peas or vines to livestock.

Site of action Group 4: synthetic auxin

Chemical family Phenoxy acetic acid

MCPB (Thistrol)

Rate 0.5 to 1.5 lb ae/a (2 to 6 pints/a)

Time Apply at six- to twelve-node stage for peas, and to Canada thistle during stem elongation but before 8 inches tall. Higher rate required during cool weather.

Remarks Prevents development of Canada thistle buds and contamination of harvested product. Some evidence exists that early-morning applications are safer to crop than afternoon applications.

Caution Do not feed treated peas or vines to livestock. Do not spray when air exceeds 90°F or when peas are moisture stressed.

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 (4 to 8 fl oz/a)

Time Apply only once per season, to susceptible broadleaf weeds less than 2 inches tall or wide.

Remarks Do not apply more than 0.5 inch of irrigation within 1 month after metribuzin application because crop may be injured. In western Oregon, try small areas before treating large ones. Warm weather or tank-mixes with bentazon have caused injury west of the Cascades. Preharvest interval is 50 days; grazing is permitted after 40 days. Ensure peas, location, or irrigation conditions are listed on product label.

Caution Restricted-use herbicide in Washington to protect surface and groundwater. Do not apply to wet crop foliage, or to very moist soil surface. Do not apply within 3 days after cool, wet, or cloudy weather or within 24 hr of other pesticide applications (except tank-mixes specified on label) to minimize risk of crop injury. Do not use on coarse, sandy, or shallow soils or on soil with less than 1.5% organic matter.

Site of action Group 5: photosystem II inhibitor

Chemical family Triazinone

quizalofop (Assure II)

Rate 0.04 to 0.08 lb ai/a (5 to 10 oz/a)

Time Apply at optimum growth stage listed on label.

Remarks Identify susceptible grasses, and add 4 quarts crop oil concentrate or 1 quart nonionic surfactant/100 gal of spray mix. Grass control may be reduced if applied immediately before or after a broadleaf herbicide.

Caution Do not mix with, or apply with, any other pesticide except as specified on label. Do not apply to plants stressed from lack of moisture, cold, or injury from herbicides, insects, or disease. Preharvest interval is 30 days. Do not exceed 0.1 lb ai/a per season.

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

Chemical family Aryloxyphenoxy propionate

sethoxydim (Poast)

Rate 0.19 to 0.375 lb ai/a (1 to 2 pint/a) depending on species, consult label.

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, high temperatures, or low fertility. Tolerant 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 15 days. Do not exceed 0.75 lb ai/a (4 pints/a) per season.

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

Chemical family Cyclohexanedione