clethodim (Select Max, Arrow, Envoy Plus, and others for nonbearing crops)
Rate 0.07 to 0.12 lb ai/A (9 to 16 fl oz/A Select Max for annual grasses; 12 to 16 oz/A Select Max for perennial grasses). Consult label for rates of other products.
Time Apply to actively growing grass weeds, including annual bluegrass, at labeled growth stage.
Remarks Read label carefully for adjuvant instructions, and for information about effects of rain within 1 hr, applications of other pesticides, or cultivation.
Caution Do not broadcast spray. Direct spray at base of the plant where grassy weeds are growing. Do not exceed 64 fl oz/A Envoy or Select Max, or 32 fl oz/A Arrow, per season. Do not apply to nonbearing crops grown for rootstock.
Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family Cyclohexanedione
fluazifop (Fusilade DX)
Rate 0.25 to 0.38 lb ai/A (16 to 24 oz/A Fusilade DX) depending on target weed species
Time Apply to actively growing grasses, or within 7 days after irrigation, as a directed spray with 1% crop oil or 0.25% nonionic surfactant.
Remarks Identify grasses and adjust rates depending on susceptibility and stage of weed growth as label instructs. 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.
Caution Preharvest interval is 1 day. Grazing is prohibited.
Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family Aryloxyphenoxy propionate
glyphosate (numerous products)
Rate Consult label
Time Apply to actively growing weeds.
Remarks Avoid contact with green foliage or suckers of crop. Preharvest interval is 14 days.
Caution Do not exceed 12.8 pints/A product per year. Follow all precautions on label.
Site of action Group 9: inhibits EPSP synthase
Chemical family None generally accepted
isoxaben (Trellis SC)
Rate 0.5 to 1.0 lb ai/A (0.66 to 1.33 lb/A product)
Time Apply late summer to early fall, in early spring, or immediately after cultivation to debris-free soil surface. Activate with 0.5 inch water or shallow cultivation before weeds begin to emerge.
Remarks Identify weeds and adjust rates according to charts listed on label for broadleaf control. Chemical stability remains adequate when left on soil surface for 21 days. Preharvest interval is 60 days.
Caution Do not apply to newly transplanted crops until the soil has settled and cracks disappear.
Site of action Group 21: inhibits cell wall synthesis Site B
Chemical family Benzamide
isoxaben + trifluralin (Snapshot 2.5 TG)
Nonbearing only
Rate 2.5 to 5.0 lb ai/A (100 to 200 lb/A product) depending on target weed
Time Apply during dormant season to crops that will not bear fruit for at least 1 year.
Remarks Apply evenly with drop or rotary-type spreader to avoid crop injury. Apply to weed-free soil. Controls many broadleaf and grass weeds that grow from seeds but will not control weeds that emerge from existing stolons, rhizomes, or root pieces. Control existing weeds with cultivation or postemergence herbicides. Activate within 3 days using 0.5 inch of water before weeds begin to emerge. See label for repeat treatments. PHI 365 days.
Caution Do not make repeat applications at 150 lb/A or greater within 60 days of a previous application. Do not apply when wind favors drift of granule from the target area.
Site of action (isoxaben) Group 21: inhibits cell wall biosynthesis Site B; (trifluralin) Group 3: microtubule assembly inhibitor
Chemical family (isoxaben) benzamide; (trifluralin) dinitroaniline
napropamide (Devrinol DF-XT, Devrinol 2-XT)
Rate 4 lb ai/A (8 lb/A Devrinol DF-XT, 8 quarts/A Devrinol 2-XT)
Time Apply after transplanting to firm soil, before weeds germinate or sawdust is spread.
Remarks On day of treatment, wet soil 2 to 4 inches deep to reduce degradation by sun and to activate herbicide. Where convenient, shallow mechanical incorporation appears to improve activation (inhibits root growth).
Site of action Group 15: inhibits very long chain fatty acid synthesis
Chemical family Acetamide
norflurazon (Solicam DF)
Blueberry only
Rate 1.95 to 3.93 lb ai/A (2.5 to 5 lb/A Solicam DF) depending on soil type
Time West of the Cascades, immediately after planting. East of the Cascades, wait 6 months after planting before applying.
Remarks Soil surface must be weed free and relatively free of plant residues or debris. Inhibits yellow pigment formation, bleaching green chlorophyll. Preharvest interval is 60 days.
Caution Do not use on nursery stock.
Site of action Group 12: bleaching; inhibits carotenoid synthesis
Chemical family Pyridazinone
oryzalin (Surflan AS and Fugitive)
Rate 2 to 6 lb ai/A (2 to 6 quarts/A product)
Time Apply after transplanting to firm soil, before weeds germinate or sawdust is spread.
Remarks Requires sprinkler irrigation, rain, or shallow cultivation (1 to 2 inches) for activation. Avoid exposure of transplant roots contacting treated soil. Inhibits mitosis, primarily in roots.
Caution Do not apply to lowbush blueberries.
Site of action Group 3: microtubule assembly inhibitor
Chemical family Dinitroaniline
pendimethalin (Satellite Hydrocap)
New plantings and bearing crops
Rate 2 to 6 lb ai/A (2 to 6.3 quarts/A product) depending on target weed species
Time Apply after transplanting to firm soil. Apply before weeds germinate and emerge. Requires sprinkler irrigation or rain (0.5 inch or more) to incorporate. May be applied preplant incorporated. May also be applied through sprinkler and drip irrigation system.
Remarks PHI 30 days. Controls several broadleaf weeds but no grasses.
Caution Do not apply more than 6 lb ai/A/year. Use lower rates on coarse soil to avoid damage.
Site of action Group 3: microtubule assembly inhibitor
Chemical family Dinitroaniline
paraquat (Gramoxone SL 2.0)
Rate 0.625 to 1 lb ai/A (2.5 to 4 pints/A Gramoxone SL 2.0)
Time Apply up to 5 times per season as a directed spray toward plant base; ensure complete wetting when weeds are small. Avoid spray contact with foliage and new shoots.
Remarks Add a nonionic surfactant or crop oil concentrate as label specifies; take care to avoid anionic formulations that react in the tank to form insoluble precipitates. Acts on contact; absorbs energy produced by photosynthesis, forming peroxides that disrupt living cells.
Caution Restricted use pesticide due to acute toxicity. For retail sale to and use only by certified applicators - not to be used by uncertified persons working under the supervision of a certified applicator. Do not ingest or inhale spray mist. Wear protective shields, respirators, and clothing. Do not let spray contact foliage, fruit, or young tree trunks. Do not graze treated areas.
Site of action Group 22: photosystem I electron diversion
Chemical family Bipyridilium
sethoxydim (Poast)
Blueberry only
Rate 0.19 to 0.47 lb ai/A (1 to 2.5 pints/A Poast) depending on target weed species
Time Identify susceptible grasses and apply at optimum growth stage listed on the label.
Remarks Add 2 pints/A of a non-phytotoxic crop oil concentrate to improve leaf absorption. Control often is erratic if grasses are stunted or stressed from drought, high temperatures, 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 Do not exceed 5 pints/A per season. Pre-harvest interval is 30 days.
Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family Cyclohexanedione
simazine (Princep 4L)
Blueberry only
Rate 2 to 4 lb ai/A (2 to 4 quarts/A Princep)
Time Apply in spring within 2 weeks after transplanting to firm soil before weeds are established. A split application of 2 quarts/A Princep 4L in the spring plus 2 quarts/A Princep 4L in the fall is also permitted.
Remarks Use lowest rate possible. Mix with low rates of other herbicides that have other types of action. On plantings less than 6 months old, use 1/2 the rate listed.
Caution Do not use on light-texture soils. Requires surface moisture to activate. Do not apply if berries are present.
Site of action Group 5: photosystem II inhibitor
Chemical family Triazine