Vineyards and Grapes
(Note: Some clones may be sensitive to certain herbicides)
GRAPES—Weed and Vegetation Management
General strategy Vegetation management in vineyards is determined by site-specific environmental factors. Weed competition and interference must be minimized within the row while trafficability and soil conservation are required between rows (see Section L.Vegetation Management in Orchards, Vineyards, and Berries in this handbook).
Cultivation Tillage controls annual weeds and suppresses perennials weeds. Cultivation is required every 3 weeks to eventually deplete perennials. Soil temperatures are increased by tillage or cultivation that keeps the soil surface bare, especially during grape maturation west of the Cascades. Growers often compromise by tilling every other row in alternate years to ensure trafficability during harvest. Adverse effects include soil erosion from sloping sites, soil compaction, and reduced water infiltration during winter rains (except in very sandy soils).
Flame weeding Propane burning will sear small broadleaf weeds, but will only reduce vegetative growth of grasses and perennial weeds, since growing points remain protected beneath the soil surface. Metal shrouds or covers conserve fuel by briefly elevating temperatures.
Herbicides Grape roots proliferate in undisturbed, competition-free strips representing one-third to half of the planting area, depending on moisture availability. New plantings require supplemental water or nearly vegetation-free conditions during the first 3 years of establishment. Choose combinations of practices that act together to achieve your desired level of vegetation management.
Managing herbicide resistance Dependence on glyphosate in vineyards is exerting strong selection pressures on weed populations and may ultimately lead to weeds that are resistant to glyphsoate. Several alternative, nonselective herbicides, listed below, have different sites of action and can be applied in rotation with glyphosate to reduce the risk of selecting for weeds that are resistant to glyphosate. Refer to Section C: Agrichemicals and their Properties: Managing Herbicide-resistant Weeds and Section C. Agrichemicals and their Properties in this handbook for more information.
Steps to avoid or manage glyphosate resistance
- Use other means to manage weeds such as cultivation, mowing, and flailing in orchards.
- Use preemergence herbicides where possible. Consider use of other nonselective herbicides such as glufosinate or paraquat with PPO inhibitors for burndown control.
- To delay development of resistance, use the full labeled rate of glyphosate.
- If continuing to use glyphosate in orchards or vineyard with resistant weeds, then tank mix glyphosate with other herbicides and make the application when the weeds are small.
- Do not let weeds go to seed, and in the case of weeds that outcross, do not let weeds produce pollen.
Mowing or flailing Mowing or flailing grass sods or weedy vegetation in aisles improves trafficability, prevents erosion, and improves soil conditions. Improved turf grass varieties, combined with water and fertilizer management for both the crop and sod, offer long-term advantages in soil management. However, caution is advised during vineyard establishment under non-irrigated conditions where vine growth may be reduced in the first 3 years from competition by most deep-rooted vegetation.
Mulches Organic mulches suppress weeds, conserve moisture, and improve soil tilth. Most polyethylene films last only one or two seasons. Woven or spun-bonded fabrics have controlled weeds for 5 to 7 years if the surface remains free of mulch or leaf debris that encourages weed germination.
GRAPES—Site Preparation
glyphosate (numerous product names)
Rate 0.47 to 4.5 lb ai/A (11 oz to 3.3 quarts/A Roundup Max)
Time Apply to weeds at least 10 days before planting the crop.
Remarks Use highest rate on field bindweed.. Rain within 6 hours after application may reduce effectiveness. Inhibits production of three amino acids and protein synthesis.
Caution Do not apply if weeds are under stress from drought, weather, or maturity.
Site of action Group 9: inhibits EPSP synthase
Chemical family None generally accepted
GRAPES—New Plantings, Soil-active Herbicides
isoxaben (Trellis)
Rate 0.495 to 0.998 lb ai/A (0.66 to 1.33 lb/A)
Time Apply after harvest in fall until 6 months before the next harvest, or immediately after cultivation, to debris-free soil surface.
Remarks Limited to 2 applications per year up to 1.33 lbs product per year. Activate with 0.5 inch water or shallow cultivation before weeds begin to emerge. Chemical stability remains adequate when left on soil surface for 21 days. Identify weeds and adjust rates according to charts on label.
Caution PHI is 165 days. 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
napropamide (Devrinol)
Rate 4 lb ai/A (8 lb/A Devrinol 50-DF)
Time Apply after transplanting to firm soil, before weeds germinate.
Remarks The day of treatment, wet soil 2 to 4 inches deep to reduce degradation by sun and to activate herbicide. If convenient, shallow mechanical incorporation appears to improve activity. Avoid exposure of transplant roots contacting soil. May be applied through irrigation system. Can be tank mixed with broad-spectrum herbicides glyphosate and paraquat.
Site of action Group 15: inhibits very long chain fatty acid synthesis
Chemical family Acetamide
oryzalin (Surflan)
Rate 2 to 6 lb ai/A (2 to 6 quarts Surflan/A)
Time Apply after transplanting to firm soil, before weeds germinate.
Remarks Requires sprinkler irrigation, rain, or shallow cultivation (1 to 2 inches) to activate. Rate depends on duration of weed control desired. Inhibits mitosis, primarily in roots.
Site of action Group 3: microtubule assembly inhibitor
Chemical family Dinitroaniline
oxyfluorfen (Goal 2XL)
Rate 1.25 to 1.5 lb ai/A (5 to 6 pints/A Goal 2XL) for preemergence control; as low as 2 pints/A for early postemergence control of susceptible species.
Time Apply only to healthy vines.
Remarks Direct the spray toward the base of vines, avoiding direct plant contact. Acts as contact, either directly on broadleaf weeds or at soil surface as weeds emerge. Controls broadleaf weeds pre- and postemergence depending on application rate and weed species.
Site of action Group 14: protoporphyrinogen oxidase inhibitor
Chemical family Diphenylether
pendimethalin (Prowl H2O, Prowl 3.3EC, and other products)
Nonbearing crop for Prowl 3.3; bearing for Prowl H2O
Rate 1.9 to 3.8 lb ai/A (2 to 4 quarts/A Prowl H2O); 1.98 to 3.96 lb ai/A (2.4 to 4.8 quarts/A Prowl 3.3EC)
Time Apply before or after planting or to 1-year dormant vines.
Remarks Spray directly on the ground beneath newly planted and 1-year-old vines. Overhead watering or rain is required (usually 0.5 inch is adequate) within 7 days for herbicide activation. Can also be applied before transplanting vines by incorporating into the top 2 inches of soil, or by applying to soil surface. Minimize contact of treated soil with the vine roots when transplanting.
Caution Do not apply over the tops of vines with leaves or open buds. Do not graze treated areas, or apply more than 6.3 quarts/A per year.
Site of action Group 3: microtubule assembly inhibitor
Chemical family Dinitroaniline
trifluralin (Treflan and several other products, EC and granular)
Rate 0.5 to 2 lb ai/A (1 to 4 pints Treflan)
Time Before transplanting, or in established bearing and nonbearing vineyards.
Remarks Apply before times of expected weed emergence or immediately after existing weeds are controlled. Apply as a directed spray to the soil and incorporate with methods that do not injure the crop. Use lower rates on sandy soils or soil containing low organic matter levels. Inhibits mitosis in roots and shoots. Preharvest interval is 60 days.
Site of action Group 3: microtubule assembly inhibitor
Chemical family Dinitroaniline
GRAPES—New Plantings—Post-emergence Contact and Translocated Applications
clethodim (Prism or Envoy)
Nonbearing crop only
Rate 0.095 to 0.123 lb ai/A (13 to 17 fl oz/A Prism)
Time Apply to actively growing grass weeds, including annual bluegrass, at growth stage listed on label.
Remarks Read label carefully for adjuvant instructions and for information about effects of rain within 1 hour, applications of other pesticides, or cultivation. Do not apply to a vine that will bear fruit in 1 year after Prism application.
Caution Do not exceed 68 fl oz/A per season.
Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family Aryloxyphenoxy propionate
diquat (Reglone)
Nonbearing only
Rate 0.375 to 0.5 lb ai/A (24 to 32 fl oz/A)
Time Apply to completely cover rapidly growing weed foliage, to facilitate planting. Add a nonionic surfactant.
Remarks Acts as contact. Absorbs energy produced by photosynthesis; forms peroxides that disrupt living cells.
Site of action Group 22: photosystem I electron diversion
Chemical family Bipyridilium
fluazifop (Fusilade DX)
Rate Refer to specific grassy weeds on label 0.25 to 0.375 lb ai/A (16 to 24 oz/A Fusilade)
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 Can now be applied to bearing grapes under supplemental label. Identify grass weeds and adjust rates, depending on susceptibility and stage of 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. Do not apply more than 24 fl oz/A per year. Do not apply twice within 14 days.
Caution PHI is 50 days. Grazing is prohibited.
Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family Aryloxyphenoxy propionate
glyphosate (numerous product names)
Rate 0.47 to 4.5 lb ai/A (11 oz to 3.3 quarts/A Roundup Max)
Time Apply to actively growing weeds either as site preparation or in nonbearing crops 1 year before first harvest.
Remarks Avoid contact with green crop foliage or suckers.
Caution Do not exceed 12.8 lb ai/A per year. Follow all precautions on label. Repeated glyphosate applications have created resistant biotypes of ryegrass in Australian orchards. To avoid weed resistance, rotate and mix weed control practices.
Site of action Group 9: inhibits EPSP synthase
Chemical family None generally accepted
sethoxydim (Poast)
Rate 0.19 to 0.47 lb ai/A (1 to 2.5 pints/A Poast)
Time Add 2 pints/A of a nonphytotoxic crop oil concentrate to improve leaf absorption.
Remarks Identify susceptible grasses and apply at optimum growth stage listed on label. Control often is erratic on grasses stunted or stressed from drought, high temperatures, or low fertility. Resistant grasses include annual bluegrass and all fine fescues; quackgrass can be suppressed.
Caution Preharvest interval is 50 days. Do not exceed 5 pints/A per season.
Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family Aryloxyphenoxy propionate
GRAPES—Established Plantings—Dormant and Non-dormant Soil-active Herbicides
dichlobenil (Casoron CS and Casoron 4G)
Rate 4 to 6 lb ai/A (100 to 150 lb/A Casoron 4G)
Time Apply midwinter, immediately before a cold rain, to reduce volatility and enhance weed suppression.
Remarks Weigh and distribute uniformly exact quantities over precisely measured areas to ensure accurate applications. Use in vineyards established at least 4 weeks, preferably the winter after planting. Oregon results over 9 years suggest perennial weeds can be suppressed with 4-, 3-, and 2-lb ai/A rates applied during 3 consecutive years.
Caution Grazing livestock is prohibited.
Site of action Group 20: inhibits cell wall synthesis Site A
Chemical family Nitrile
diuron (Karmex and several other products)
Rate 1.6 to 3.2 lb ai/A (2 to 4.8 lb ai/A in Idaho)
Time Apply in winter as single application, or apply half-doses in October and March.
Remarks Reduce rate or rotate with other herbicides after effective weed control is achieved. Use in vineyards established at least 3 years.
Caution Do not apply on very sandy or gravelly soils. Can be rotated with simazine or other herbicides to reduce weed shifts.
Site of action Group 7: photosystem II inhibitor
Chemical family Substituted urea
flumioxazin (Chateau)
Rate 0.188 to 0.38 lb ai/A (6 to 12 oz/A Chateau). Refer to organic matter, soil types, and rates listed on label for various broadleaf weeds.
Time Pre- or post-emergence (weeds up to 2 inches tall). Preferred time is fall, to maximize the potential for rain to activate and set the herbicide. Tank mix with approved herbicides if weeds are large, or if weedy vegetation will keep Chateau from reaching the soil surface.
Remarks Residual or postemergence weed control can be achieved by adjusting rates or labeled tank-mixes (see label). Use a surfactant to improve postemergence control. If grapes are non-dormant, only apply before budbreak, and after final harvest, unless using shielded application equipment.
Caution Do not apply to vines established less than 2 years, unless they are trellised at least 3 ft from the ground, and protected by nonporous wraps, grow tubes, or waxed containers. Do not apply within 300 yards of bearing pears. Do not mow treated area after final harvest. Preharvest interval is 60 days.
Site of action Group 14: protoporphyrinogen oxidase inhibitor
Chemical family Diphenylether
indaziflam (Alion)
Rate 0.065 lb ai/A (5 oz/A product)
Time Apply in fall to early spring to firmed soil that does not have cracks.
Remarks Vines must be 5 years old and planted 12 or more inches deep. Existing vegetation must be controlled with glyphosate or burndown herbicides such as glufosinate or paraquat. Controls annual broadleaf and grass weeds, and perennial weeds from seed only. Existing perennial/biennial weeds growing from roots will not be controlled. Rainfall or irrigation of 0.25 inch or more within 3 weeks of application is required for maximum efficacy. Pre-harvest interval is 14 days.
Caution Avoid direct contact with foliage, green bark, or roots of desired species. Do not apply to sand or to soil that is more than 20% gravel. Clean spray tanks thoroughly after use. Surface and groundwater advisories are included on the label because of potential to harm non-target aquatic organisms, and potential for runoff and percolation to ground water. A well maintained and level vegetated buffer strip of 25 ft or more will help reduce runoff.
Site of action Group 29: inhibits cellulose biosynthesis
napropamide (Devrinol 50DF)
Rate 4 lb ai/A (8 lb/A Devrinol 50DF)
Time Apply fall through spring before weeds germinate, or apply foliar-active herbicide to control existing vegetation.
Remarks Irrigation or shallow incorporation is recommended for treatments made November through February if no rain falls within 2 weeks after application. Irrigate within 24 hours to wet soil 2 to 4 inches deep if applied March through October. Shallow mechanical incorporation seems to enhance activity. Excessive plant residues on soil surface reduce performance.
Caution Preharvest interval is 35 days. Inhibits root growth.
Site of action Group 15: inhibits very long chain fatty acid synthesis
Chemical family Acetamide
norflurazon (Solicam)
Rate 0.98 to 3.93 lb ai/A (1.25 to 5 lb/A Solicam) depending on soil type.
Time Apply to weed-free soil in fall to early spring, when soil surface is reasonably free of plant residue. Requires ample rain to activate.
Caution Do not use on grapes established less than 2 years in the field. Do not use on gravelly, sandy, or loamy sand soils. Preharvest interval is 60 days.
Site of action Group 12: bleaching; inhibits carotenoid biosynthesis
Chemical family Pyridazinone
oryzalin (Surflan)
Rate 2 to 6 lb ai/A (2 to 6 quarts/A Surflan) depending on duration of weed control needed. Do not exceed 12 lb/A per year.
Time Apply late fall or early spring to bare soil, or after existing vegetation has been destroyed by tillage or use of a foliar-active herbicide.
Remarks Use higher rates or split treatments and apply in fall and spring for longer residual control. Irrigate with at least 0.5 inch of water or rain to activate herbicide. Shallow cultivation can control newly germinated weeds without reducing herbicide activity. Allow 24 months before planting vegetables after grapes. Inhibits mitosis, primarily in roots.
Site of action Group 3: microtubule assembly inhibitor
Chemical family Dinitroaniline
oxyfluorfen (Goal 2XLand Goal Tender)
Rate 1.25 to 1.5 lb ai/A (5 to 6 pints/A Goal 2XL) for preemergence control in dormant grapes; as low as 1 to 2 pints/A for early postemergence control of susceptible species in non-dormant grapes (0.5 to 3 pints/A Goal Tender)
Time Apply after harvest, but before bud-swell in spring.
Remarks Direct the spray toward the base of vines in late winter or spring, avoiding direct plant contact. Controls broadleaf weeds pre- and post-emergence, depending on time and rate of application and weed species. Can be tank mixed with glufosinate (Rely) or paraquat (Gramoxone) or other preemergence herbicides such as napropamide (Devrinol), diuron (Karmex), or pronamide (Kerb) to improve residual weed control. Acts on contact, either directly on broadleaf weeds, or at soil surface as weeds emerge. Pre-harvest interval is 14 days.
Caution Do not apply when fruit is present.
Site of action Group 14: protoporphyrinogen oxidase inhibitor
Chemical family Diphenylether
pendimethalin (Prowl H2O)
Rate 3 to 6 lb ai/A (3.2 to 6.3 quarts/A Prowl H2O)
Time Apply any time after fall harvest, during winter dormancy, and in the spring before budbreak.
Remarks Spray directly on ground beneath grape vines, before weeds emerge. Overhead watering or rain is required (usually 0.5 inch is adequate) within 7 days for herbicide activation. Can also apply before transplanting vines, by incorporating into the top 2 inches of soil or by applying to soil surface. Minimize contact of treated soil with the vine roots when transplanting.
Caution Do not apply during or after bud swell in the spring. Do not apply over the tops of vines with leaves or open buds. Do not graze treated areas or apply more than 6.3 quarts/A per year. Preharvest interval is 90 days.
Site of action Group 3: microtubule assembly inhibitor
Chemical family Dinitroaniline
pronamide (Kerb)
Rate 1 to 4 lb ai/A (2 to 8 lb/A Kerb)
Time Apply only once in fall or winter, preferably October to December when temperature is 55°F or below.
Remarks Use lower rates on annual grasses and light soil textures; higher rates on perennial grasses such as quackgrass and fine textured soils. Requires moisture from rain or irrigation for activation. Use only on vineyards established at least 1 year, or on spring-planted grapes established at least 6 months. Inhibits root growth.
Caution A restricted-use herbicide.
Site of action Group 3: microtubule assembly inhibitor
Chemical family Benzamide
rimsulfuron (Matrix FNV)
Rate 0.063 lb ai/A (4 oz/A Matrix FNV per year)
Time Applied before or shortly after weed emergence.
Remarks Apply uniformly to the vineyard floor, or as a directed application at the base of the vine. Crops must be established 1 year before application. Results are best if soil is moist at time of application and receives 0.5 inch of rain or irrigation within 2 weeks after application. Do not disturb the soil after application or weed control will be compromised. Two applications separated by 30 days are allowed if applied in bands that cover half of the vineyard. Preemergence control of puncturevine quackgrass, mallow and common dandelion from seed; suppression of yellow nutsedge; Preharvest interval is 14 days. Controls common mallow and dandelion pre-emergence, suppresses nutsedge and quackgrass.
Caution Avoid spray contact with foliage or fruit (except undesirable suckers) or drift onto adjacent crops. Clean spray tank carefully. Minimize contact with fruit or foliage.
Site of action Group 2: acetolactate synthase (ALS) inhibitor
Chemical family Sulfonylurea
simazine (Princep)
Rate 2 to 4 lb ai/A (2 to 4 quarts/A Princep 4L)
Time Apply in winter as single application, or apply half-doses in October and March.
Remarks Reduce rate or rotate with other herbicides after achieving weed control. Requires surface moisture for activation.
Caution Do not apply on very sandy or gravelly soils. Can be rotated with diuron or other herbicides to reduce weed shifts. Do not use in vineyards established less than 3 years, or crop injury may occur
Site of action Group 7: photosystem II inhibitor
Chemical family Substituted urea
trifluralin (several products)
Rate 0.5 to 2 lb ai/A (1 to 4 pints/A Treflan)
Time Apply and incorporate immediately by thoroughly mixing 1 to 2 inches deep, using equipment that will not injure roots.
Caution Preharvest interval is 60 days. Inhibits mitosis in roots and shoots.
Site of action Group 3: microtubule assembly inhibitor
Chemical family Benzamide
GRAPES—Established Plantings—Directed Applications in Non-dormant Grape Rows
2,4-D amine + glyphosate (Nufarm Recoil Broad Spectrum Herbicide)
Rate 0.13 to 0.54 lb ae/A 2,4-D and 0.20 to 0.79 lb ae/A glyphosate (1 to 4 quarts/A)
Time Apply after shatter following bloom, before grape shoots reach the ground. Apply to vigorously growing weeds that are in bud to early bloom stage.
Remarks Use a directed-shielded boom with low-pressure flooding nozzles to reduce possible drift and injury. Grapes are extremely sensitive to 2,4-D. Avoid all contact or drift to leaves, young shoots, and stems. May be used to suppress or control Canadian thistle and field bindweed. Mimics natural plant hormones.
Caution Do not apply to vineyards established less than 3 years. Injury potential to grapes is high if applied outside the dormant season. Use a hooded boom, or single nozzle and flooding type nozzles, to deliver a coarse spray. Apply when soil is moist after irrigation, then wait 7 to 10 days before irrigating again.
Site of action Group 4: synthetic auxin
Chemical family Phenoxy acetic acid
bentazon (Basagran herbicide)
Non bearing grapes only
Rate 0.75 to 1 lb ai/A (1.5 to 2 pts/A)
Time Spring to early summer, depending on growth stage of weeds.
Remarks Supplemental label (Arysta LifeSciences) for non-bearing crops. Useful for suppression and control of yellow nutsedge, Canada thistle, and musk thistle. For Canada thistle apply 2 pints/A when plants are between 8 inches tall and bud stage. Apply a second application 2 weeks later if needed. For nutsedge, apply 1.5 to 2 pints/A when plants are 6-8 in tall, and make a second application 7-10 days later if needed. Always add a crop oil concentrate. Use no more than 2 lbs ai/A per year. Irrigate to make sure plants are actively growing before applying bentazon. Do not cultivate or mow for 5 days after application. Weeds growing under drought conditions may not be adequately controlled.
Caution Apply as a directed spray, away from the crop. Do not apply within one year of crop harvest.
Site of action Group 6: photosystem II inhibitor
Chemical family Benzothiadiazole
carfentrazone-ethyl (Aim EC)
Rate 0.016 to 0.031 lb ai/A (1 to 2 fl oz/A Aim EC)
Time Directed spray and with hooded sprayers within and between rows.
Remarks Preharvest interval is 3 days. Control is enhanced with COC (1%) or NIS (0.25%).
Caution Care must be taken not to allow spray mist to contact desirable fruit, foliage or green stem tissue. Can be used for sucker control.
Site of action Group 14: inhibits protoporphyrinogen oxidase
Chemical family Triazinone
clove or clove leaf oil (Matran EC, Matratec)
Rate 5 to 8% 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 emerges, or between rows after emergence; avoid contact with desirable foliage. Directed sprays or hooded sprayers are recommended to protect desirable foliage. Works best on annual weeds less than 6 inches. Performance may be erratic depending on environmental conditions. Bright sunlight improves efficacy. No preharvest or re-entry interval.
glufosinate ammonium (Rely 280)
Rate 0.88 to 1.5 lb ai/A; (48 to 82 fl oz/A depending on weed size)
Time Apply to actively growing weeds as a directed spray or spot treatment according to weed growth stage.
Remarks Avoid drift to, or treatment of, desirable foliage or green bark during establishment year.
Caution Do not exceed 4.5 lb ai/A per 12-month season. Do not graze or apply within 14 days of harvest.
Site of action Group 10: glutamine synthase inhibitor
Chemical family Phosphinic acid
glyphosate (numerous products)
Rate 0.47 to 4.5 lb ai/A (11 oz to 3.3 quarts/A Roundup Max)
Time Select application equipment to prevent crop injury by directing spray, or use selective applicators.
Remarks Adjust concentration depending on equipment. See label for rate and time of application, especially for perennial weeds. Adding surfactant or mixing ammonium sulfate according to label may improve control of slightly stressed weeds.
Caution Do not let drift or mist contact green foliage or bark, suckers, or vines and renewals less than 3 years old. Preharvest interval is 14 days. If repeat applications are needed, do not exceed 10.6 lb ai/A per year. Repeated glyphosate applications have created resistant biotypes of ryegrass in Australian orchards. To avoid weed resistance, rotate and mix weed control practices.
Site of action Group 9: inhibits EPSP synthase
Chemical family None generally accepted
glyphosate
Rate 2 to 4 quarts/A to control Canada thistle
Time Apply after shatter following bloom, before grape shoots reach the ground. Apply to vigorously growing weeds that are in bud to early bloom stage.
Remarks Use a directed-shielded boom with low-pressure flooding nozzles to reduce possible drift and injury. Grapes are extremely sensitive to 2,4-D. Avoid all contact or drift to leaves, young shoots, and stems. Mimics natural plant hormones.
Caution Do not apply to vineyards established less than 3 years. Injury potential to grapes is high if applied outside the dormant season. Do not allow 2,4-D to contact suckers or shoots emerging from the main stem.
Site of action Group 4: synthetic auxin
Chemical family Phenoxy acetic acid
glyphosate (several products)
Rate 0.47 to 4.5 lb ai/A (11 oz to 3.3 quarts/A Roundup Max)
Time Wick-wiper: Mix 1 gal product with 2 gal water and apply to weeds.
Remarks Avoid contact with desirable vegetation. In severe infestations, reduce equipment ground speed, or apply in two directions to ensure contact with wiper. (See remarks above.)
Site of action Group 9: inhibits EPSP synthase
Chemical family None generally accepted
limonene (lemon grass oil) (Green Match)
Rate 14% dilution rate, 20% for spot treatment of difficult to control weeds.
Time Up to first fruit set, when weeds are less than 6 inches tall.
Remarks Broadspectrum, non-selective contact herbicide that does not translocate. Spot treatments allowed in bearing crops up to 1 wk before harvest. Do not exceed 8.5 gal/A per application in bearing crops. Most effective on annual weeds. OMRI listed, NOP compliant, and WSDA approved organic burndown herbicide for use in crop and non-crop sites. Foliage contacted by Green Match will be damaged. Directed sprays or hooded sprayers are recommended to protect desirable foliage. Coverage is very important. Leaf damage is visible within hours. Cool weather may slow activity. No re-entry interval. This herbicide causes rapid wilting or necrosis of the leaves due to removal of waxy cuticle.
pyraflufen (Venue)
Rate 0.001 to 0.006 lb ai/A (0.7 to 4 fl oz product/A)
Remarks Apply as a directed application to actively growing weeds less than 4 inches high, or rosettes less than 3 inches in diameter. Use lower rate for small weeds and higher rate for larger weeds. Do not exceed 6.8 fl oz/A or three applications per season. Allow at least 30 days between applications. Apply during postharvest until prebloom. Mixing this herbicide with another herbicide increases the weed spectrum and is highly recommended.
Caution This product is a contact, nonselective, broadleaf herbicide. Avoid contact with desirable foliage, green bark, or fruit.
Action in plant Inhibits protoporphyrinogen oxidase (PPO) that disrupts cell membranes.
Site of action Group 14: protoporphyrinogen oxidase inhibitor
Chemical family Phenylpyrazole
paraquat (Gramoxone Inteon)
Rate 0.625 to 1 lb ai/A (2.5 to 4 pints/A Gramoxone Inteon)
Time Apply as a directed shielded spray toward base of vines, when weeds are growing vigorously and new growth is 1 to 6 inches high.
Remarks Add a nonionic surfactant or crop oil concentrate according to label; avoid anionic formulations that react in the tank to form insoluble precipitates. Avoid windy conditions. Acts on contact; absorbs energy produced by photosynthesis forming peroxides that disrupt living cells. Five applications allowed per year. Treat when suckers are less than 8 inches long.
Caution A restricted-use herbicide. Do not ingest or inhale spray mist. Wear protective face shields, respirators, and clothing. Do not allow spray to contact green stem, fruit, or foliage.
Site of action Group 22: photosystem I electron diversion
Chemical family Bipyridilium
sethoxydim (Poast)
Rate 0 .19 to 0.47 lb ai/A (1 to 2.5 pints/A Poast)
Time Identify susceptible grasses and apply at optimum growth stage listed on the label.
Remarks Add 2 pints/A of a nonphytotoxic crop oil concentrate to improve leaf absorption. Control often is erratic on grasses stunted or stressed by 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 50 days. Do not exceed 5 pints/A per season.
Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family Aryloxyphenoxy propionate
GRAPES—Sucker Control in Non-Dormant Grapes
oxyfluorfen (Galigan,Goal 2XL, Goal Tender)
Oregon and Washington only
Rate 0.25 to 0.5 lb ai/A (0.5 to 1 pints/A Goal Tender)
Time Apply as a directed ground spray to suckers growing from plant base up to 12 inches tall.
Remarks Apply to suckers less than 12 inches long. Immature, expanding leaves at time of contact are most susceptible. Complete sucker control requires removing canes by hand. The highest rate, or a second application, may be required for acceptable control or suppression of grape suckers. Not for use on table grapes. Can be tank mixed with glufosinate (Rely) or paraquat (Gramoxone) to enhance sucker control.
Caution Do not exceed 1.5 lb ai/A per season. Preharvest interval is 60 days. Can be applied to non-dormant grapes up to 3 weeks after bloom.
Site of action Group 14: protoporphyrinogen oxidase inhibitor
Chemical family Diphenylether
carfentrazone-ethyl (Aim EC)
Rate 0.031 lb ai/A (2 fl oz/A Aim EC)
Remarks Suckers must be young and succulent. Control is enhanced with COC (1%) or NIS (0.25%).
Caution Care must be taken not to allow spray mist to contact desirable fruit, foliage or green stem tissue. Do not use on seedlings.
Site of action Group 14: inhibits protoporphyrinogen oxidase
Chemical family Triazinone