caprylic plus capric acids (Suppress)
Rate 3% to 9% dilution in 25 to 100 gal of water, depending on weed size, temperature, and sunlight intensity.
Time Preemergence or any time during the crop growing season to control weeds in row-middles or to burn down unwanted crop vegetation.
Remarks OMRI approved burndown. Not selective in broadleaf vegetable crops, and crop will be injured any time the spray contacts plant tissue. Do not apply to weeds when wet from dew, rain or water. Do not water within 2 hours after application. Do not apply if rainfall is expected within 2 hours of spray. For mature weeds up to 6 inches tall, use the higher rates in up to 100 gal of water/a.
Rate Up to 0.031 lb ai/a (up to 2 fl oz/a)
Time Preemergence or any time during the crop growing season to control weeds in row-middles or to burn down unwanted crop vegetation (e.g., in hops).
Remarks The EPA classifies carfentrazone as a low-risk herbicide, and it is therefore registered on many crops as a post directed-application. Refer to the table "Registered Uses of Aim" in this chapter for labeled uses of this herbicide in the Pacific Northwest.
Caution This herbicide is not selective in broadleaf vegetable crops, and crop will be injured any time the spray contacts plant tissue. Spray equipment clean-out: Aim herbicide is active at very low rates; ensure that spray tanks are thoroughly cleaned before pesticides are applied to other crops. Clean the spray tank as soon after use as possible with recommended cleaning procedures on the label.
Site of action Group 14: protoporphyrinogen oxidase inhibitor
Chemical family Triazinone
clove leaf oil (Matratec EC)
Rate 5% to 10% dilution in 25 to 100 gal of water, depending on weed size, temperature, and sunlight intensity.
Time Before weeds are 6 inches tall.
Remarks OMRI-listed and WSDA-approved herbicide for in-crop use. Apply before crop emergence, or between rows after emergence, avoiding contact with desirable foliage. Directed sprays or hooded sprayers are recommended. Works best on annual weeds less than 6 inches. Performance may be erratic depending on environmental conditions. Bright sunlight improves efficacy. No preharvest interval or reentry interval.
d-limonene or lemongrass oil (Avenger AG)
Rate 13% to 25% dilution depending on weed size and species.
Time When weeds are less than 6 inches tall.
Remarks OMRI-listed, NOP-compliant, and WSDA-approved organic burndown herbicide for use in crop and noncrop sites. Foliage contacted by Avenger will be damaged. Directed sprays or hooded sprayers are recommended. Coverage is very important. Leaf damage is visible within hours. Cool weather may slow activity. No reentry interval. Fast wilting or necrosis of the leaves may occur due to removal of waxy cuticle.
glyphosate (Roundup and many others)
Rate 0.5 to 2 lb ae/a
Time Apply to seedbeds before or shortly after the crop is planted or emerges.
Remarks Refer to the table "Registered Uses of Glyphosate" in this section for general guidelines; read the label carefully to determine proper timing and which product can be applied to each crop.
Caution Glyphosate may injure some crops if the soil is extremely sandy, or if the planter did not properly close the seed row. Do not let glyphosate contact seeds or any part of the seedling, as crop failure will result.
Site of action Group 9: inhibits EPSP synthase
Chemical family None generally accepted
paraquat (Gramoxone SL 2.0) or diquat (Reglone)
Rate Consult label
Time Many crops and situations, including weed control in row middles after crop establishment; consult labels.
Remarks Apply between rows in vegetable crops. Use paraquat if grasses are present. 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. Exposed crop plants may be killed if these herbicides contact sufficient living tissue.
Caution Paraquat is a restricted-use herbicide. Do not ingest or inhale spray mist. Wearing protective face shields, respirators, and clothing is advised. Both herbicides act on contact; they absorb energy produced by photosynthesis, forming peroxides that disrupt living cells.
Site of action (both) Group 22: photosystem I electron diversion
Chemical family (both) Bipyridilium