Seedbeds and Early Establishment

See "Section N. Vegetable Crops: Site Preparation, Stale Seedbeds, and Selective Postemergence Applications" for additional options for weed control during asparagus establishment.

clethodim (several trade names)

Rate 0.07 to 0.12 lb ai/a

Time Apply to actively growing grasses at the time specified on the label. Add nonionic surfactant, at 0.25% v/v, to spray mix.

Remarks Adjust rate for target weeds. Use the higher rates for perennial grasses.

Caution Do not harvest within 1 day of treatment. Do not exceed 16 fl oz/a of product per application or 64 fl oz/a (0.5 lb ai/a) per season. Allow at least 14 days between treatments.

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

Chemical family Cyclohexanedione

fluazifop (Fusilade DX)

Rate 0.09 to 0.375 lb ai/a (6 to 24 oz/a product)

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, low fertility, grass stage of growth, or environmental factors. 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 for susceptibility and stage of weed growth according to label instructions.

Caution Do not exceed 24 oz/a product per application or 48 oz/a product per season. Grazing is prohibited.

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

Chemical family Aryloxyphenoxy propionate

halosulfuron (Sandea)

Rate 0.023 to 0.073 lb ai/a (0.5 to 1.5 oz/a product)

Time For nursery and transplanted crowns. Do not apply sooner than six weeks after fern emergence.

Remarks Controls several broadleaf weeds and yellow nutsedge. A surfactant is not recommended as increased asparagus injury may result. Spray on asparagus ferns may cause temporary yellowing; minimize crop injury by using drop nozzles to direct spray below the ferns.

Caution A maximum of 2 applications may be made per crop-cycle. Do not exceed 1.5 oz ai/a (2 oz/a product) per 12 month period. Use a minimum of 15 gallons of water per acre. Consult the label for crop rotation restrictions.

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

Chemical family Sulfonylurea

linuron (Lorox DF)

Rate 1 to 2 lb ai/a (2 to 4 lb/a product)

Time Preemergence: Apply after planting seed 1 to 1.5 inches deep and spraying a 1-inch band of activated charcoal on soil surface directly over row. The activated charcoal will adsorb and inactivate herbicide.

Remarks Sprinkler irrigation or rain (0.5 to 1 inch) is required for herbicide activation.

Caution Do not use on sands, loamy sands, or soils with less than 1% organic matter. Weed control will be reduced in soils with high organic matter (greater than 5% and peat or muck). See label for replanting instructions if initial planting fails.

Site of action Group 7: photosystem II inhibitor

Chemical family Substituted urea

linuron (Lorox DF)

Rate 0.5 to 1 lb ai/a (1 to 2 lb/a product)

Time Postemergence: On direct-seeded or newly planted crowns. Apply once or twice when ferns are 6 to 18 inches tall, and weeds are less than 4 inches tall.

Caution Do not use a surfactant or fertilizer solution. Do not exceed 2 lb ai/a per year (see remarks above).

Site of action Group 7: photosystem II inhibitor

Chemical family Substituted urea

pendimethalin (Prowl H2O, Satellite Hydrocap)

Rate 1.14 to 3.9 lb ai/a (2.4 to 8.2 pints/a). On sandy soils: 2.4 pints/a maximum.

Time Apply preemergence to newly planted crowns.

Caution Do not apply to direct-seeded asparagus. Assure that crowns are fully covered with 2 to 4 inches of soil.

Site of action Group 3: microtubule assembly inhibitor

Chemical family Dinitroaniline

sethoxydim (several trade names)

Rate 0.19 to 0.47 lb ai/a

Time Apply at optimum growth stage as directed on label. Add 2 pints/a nonphytotoxic crop oil concentrate to improve leaf absorption. Control often is erratic on grasses stressed by drought, high temperatures, or low fertility. Resistant grasses include annual bluegrass and all fine fescues; quackgrass can be suppressed.

Remarks Identify susceptible grasses and adjust rates for susceptibility and stage of weed growth according to label instructions.

Caution Do not harvest within 1 day of treatment. Do not exceed two applications or 5 pints/a per season. Allow at least 14 days between sequential applications.

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

Chemical family Cyclohexanedione

terbacil (Sinbar WDG)

Rate 0.8 to 1.6 lb ai/a (1 to 2 lb/a product)

Time Apply after planting seed 1 to 1.5 inches deep and spraying a 1-inch band of activated charcoal on soil surface directly over row. The activated charcoal will adsorb and inactivate herbicide.

Remarks Sprinkler irrigation (0.5 to 2 inches) or rain is required to activate herbicide.

Caution Do not use on soils containing less than 1% organic matter or on gravelly soils. See label for replanting instructions if initial planting fails. Inhibits photosynthesis.

Site of action Group 5: photosystem II inhibitor

Chemical family Uracil