Established Plantings-Preemergent

dichlobenil (Casoron CS and Casoron 4G)

Rate 2 to 3.9 lb ai/a (1.4 to 2.8 gal/a Casoron CS); 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 lb/a)

Time Apply in winter as single application, or apply half-doses in October and March. Rainfall or irrigation needed to activate herbicide.

Remarks Reduce rate or rotate with other herbicides after effective weed control is achieved. Use in vineyards established at least 3 years or on vines that have trunks greater than 1.5 inches in diameter. Will control some very small emerged weeds, particularly if applied with an adjuvant.

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

indaziflam (Alion)

Rate 0.046 to 0.065 lb ai/a (3.5 to 5 oz/a product) depending on percent organic matter content of soil.

Time Apply in fall to early spring to firmed soil that does not have cracks.

Remarks Begin applications 3 years after vines have been planted and are exhibiting good growth and vigor. Ensure that the grapes have 6 inches of soil barrier between the soil surface and the root system. 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. Lower rates may be sufficiently effective. Preharvest 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. Time between applications is 90 days. Clean spray tanks thoroughly after use. Surface and groundwater advisories are included on the label because of potential to harm nontarget 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 DF-XT or 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 for DF formulation, 70 days for DF-XT. 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. Inhibits mitosis, primarily in roots.

Site of action Group 3: microtubule assembly inhibitor

Chemical family Dinitroaniline

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. Clean cultivation before application is preferable but not necessary because Kerb will control some small weeds that have emerged. 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

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 before transplanting or prior to periods of weed germination or immediately after existing weeds are controlled.

Remarks 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