Postemergence

clethodim (Select 2EC; Prism in Oregon only; or Select Max)

Rate 0.094 to 0.125 lb ai/a (6 to 8 fl oz/a Select 2EC; 9 to 16 fl oz/a Select Max). Consult label for rate required to control different grasses.

Time Apply to actively growing grasses at recommended weed heights.

Remarks Add crop oil concentrate as described on label. Do not exceed 8 fl oz/a per season.

Caution Consult 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

ethofumesate (Nortron SC)

Carrots only, in Oregon and Washington only

Rate 2 lb ai/a (64 oz/a) to carrots with two to four true leaves

Time Apply after planting and activate with at least 0.5 inch water.

Remarks Do not use smaller than 50 mesh screen and avoid overlaps, which may increase risk of crop injury. Rain or irrigation within 6 hr after irrigation may reduce weed control. Do not cultivate more than 2 inches deep.

Caution May cause temporary leaf fusion, distortion, and stunting when used according to label directions and under normal growing conditions. Nortron may cause stand loss if the crop is under stress. Apply in evening if air was warmer than 80°F during the day. If crop is lost due to unfavorable growth conditions after application, do not plant anything except sugar beets, table beets, carrots, onions, garlic, shallots, or ryegrass.

Site of action Group 16: unknown

Chemical family Benzofuran

fluazifop (Fusilade DX)

Carrots only

Rate Refer to label for rates on specific grasses

Time Apply to actively growing grasses as a directed spray with 1% crop oil or 0.25% nonionic surfactant. Results often are erratic on grasses stressed from lack of vigor, drought, high temperature, or low fertility. More mature grasses and quackgrass can be controlled but may require two applications. Annual bluegrass and all fine fescues resist treatment.

Remarks Identify grasses, and adjust rates, depending on susceptibility and stage of weed growth according to label instructions. Inhibits fatty acid production, cell membranes, and new growth.

Caution Preharvest interval is 45 days. Do not exceed 48 oz/a per year. Grazing is prohibited.

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

Chemical family Aryloxyphenoxy propionate

linuron (Lorox DF)

Carrots, transplanted celery, celeriac

Rate 0.75 to 1.5 lb ai/a (1.5 to 3 lb/a Lorox DF)

Time Apply postemergence when carrots are 3 inches tall, or when celery and celeriac are established after transplanting but are less than 8 inches tall.

Remarks Treat grass weeds less than 2 inches tall and broadleaf weeds less than 6 inches tall. Do not exceed 40 psi spray pressure. Weed control may be poor if daytime high temperature is below 50°F. Crop may be injured if herbicide is mixed with surfactants, nitrogen, or fertilizer solution, or if temperatures exceed 85°F. Repeat applications on carrots may be made but do not exceed a total of 3 lb/a product.

Caution Carrot varieties differ in their resistance; determine tolerance to linuron before applying to prevent possible crop injury. Do not apply on sand, loamy sands, gravelly soils, or soils with less than 1% organic matter. Do not apply by air. Consult label for planting rotation crops within 12 months. Preharvest interval is 14 days for carrots, 67 days for celery. REI Is 8 days for handset irrigation in celeriac,

Site of action Group 7: photosystem II inhibitor

Chemical family Substituted urea

metribuzin (Metribuzin 75DF and 4L)

Carrots only

Rate 0.25 lb ai/a (0.33 lb/a of Metribuzin 75DF or 0.5 pints/a Metribuzin 4L)

Time Apply after carrots form five to six true leaves but before weeds are 1 inch high or wide.

Remarks Earlier applications will result in excessive crop injury.

Caution If needed, repeat application after at least 3 weeks, but do not exceed 0.5 lb ai/a per year. Preharvest interval is 60 days. Do not apply within 3 days of any other chemical or within 3 days after periods of cool, wet, or cloudy weather or on very hot days. Leaf tissue may be temporarily chlorotic or burned. For carrots with unknown tolerance, treat only a small area to determine crop safety.

Site of action Group 5: photosystem II inhibitor

Chemical family Triazinone

prometryn (Caparol 4L)

Carrots, celery, and celeriac

Rate 1 to 2 lb ai/a (2 to 4 pints/a Caparol per application). Up to 3 applications on carrots but only PRE or POST on celery and celeriac).

Time Apply after planting through 6-leaf stage of carrot; for celery, after planting or after 2-3 leaf stage; for celeriac, apply after transplanting at 6-8 leaf stage.

Remarks Do not exceed 8 pints/a of Caparol 4L per carrot crop cycle, or 4 pts/a for celery or celeriac. Application may be made over the crop. Use in at least 20 gal/a spray volume. Apply before weeds are 2 inches tall. Use crop oil if weeds are larger than 2 in. PHI is 30 days for carrot, 40 days for celery, and 60 days for celeriac.

Caution Do not exceed 8 pints/a per crop. Rotation intervals are 5 months for cabbage, carrots, celeriac, celery, corn, dill, fennel, and peas, 8 months for onions and red beets, and 12 months for all other crops.

Site of action Group 5: photosystem II inhibitor

Chemical family Triazine

sethoxydim (Poast)

Rate 0.5 lb ai/a (2.5 pints/a) for carrots and parsnip; 0.28 lb ai/a (1.5 pints/a) for celery

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. Results often are erratic on grasses stressed from lack of vigor, drought, high temperature, or low fertility. Resistant grasses include annual bluegrass, and all fine fescues; quackgrass can be suppressed. Inhibits fatty acid production, cell membranes, and new growth.

Caution Preharvest interval is 14 days for parsnip, 30 days for carrots and celery. Do not exceed 5 pints/a for carrots or 3 pints/a for celery per season.

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

Chemical family Cyclohexanedione