Crop and Pest Management Guidelines

A Cornell Cooperative Extension Publication
34161

6.5 Postemergence Herbicides

34412

AIM

AIM (carfentrazone-ethyl) - read the label

Signal word: CAUTION

Medical emergency: (800) 331-3148

Selected uses: Postemergence control of certain susceptible broadleaf weeds and burn down of grapevine suckers

Rate: For broadleaf weed control, apply up to 2 fl. oz. per acre surface sprayed. Lower rates can be used to control small seedling weeds at the 2 to 3-leaf stage; higher rates are needed for larger weeds up to the 6-leaf stage. Applications to weeds beyond the six-leaf stage may result in only partial control. For burn down of grapevine suckers, apply at the maximum use rate (2 fl. oz.) per acre surface sprayed. Add a non-ionic surfactant (NIS) containing at least 80% active ingredient at 2 pt. per 100 gallons, or a crop oil concentrate (COC) at one gallon COC per 100 gallons, or methylated seed oil (MSO).

Timing: Aim may be applied at any time during the season, but do not allow spray mist to contact desirable fruit, foliage, or green bark. Suckers and other undesirable growth must be treated when the tissue is young (not mature or hardened off). Multiple applications per season are allowed, but do not apply more than 7.9 fl. oz. per season. Do not make applications less than 14 days apart or within 3 days of harvest.

Comments: Aim is very effective in controlling grapevine suckers, and also controls some small broadleaf weeds. Treated suckers turn brown within 1-2 days of application, but multiple applications may be necessary to obtain season-long sucker control. Refer to the label for a list of susceptible broadleaf weeds. Aim may be tank-mixed with other preemergence and postemergence herbicides; observe the other product's label restrictions.

34413

GRAMOXONE MAX, *GRAMOXONE SL 2.0

^*GRAMOXONE MAX, *GRAMOXONE SL 2.0 (paraquat) - RESTRICTED USE PESTICIDE - read the label

Signal word: DANGER

Medical emergency: (800) 888-8372

Selected uses: Postemergence burn down of all weeds in new or established vineyards and burn down of grapevine suckers up to 8 inches long.

Rate: *Gramoxone SL 2.0 contains 2 lb. of the active ingredient, paraquat, per gallon. Apply 2.5-4 pt per acre surface sprayed. ^*Gramoxone Max is a more concentrated formulation that contains 3 lb of the active ingredient, paraquat, per gallon. Apply 1.75-2.7 pt ^*Gramoxone Max per acre surface sprayed. Always add a nonionic surfactant (NIS) or crop oil concentrate (COC). Add NIS at 1 pt per 100 gal (75% or more surface-active agent), or NIS at 2 pt per 100 gal (50-74% surface-active agent), or COC at 1 gal per 100 gal. The label permits applications in as low as 10 gal per treated acre, but spray volume should be increased as necessary to obtain complete coverage of target weeds or suckers without runoff from the target foliage.

Timing: *Gramoxone should be applied to emerged weeds when they are small. Weeds 1-6 inches tall are easiest to control. Contacted plant foliage wilts and desiccates within hours of application, with complete necrosis in 1-3 days. For burndown of grapevine suckers, treat when sucker growth is no more than 8 inches long. For mature woody weeds, perennial weeds, late-germinating weeds, and green suckers, retreatment or spot -treatment may be necessary. Late season applications to weeds should be made to avoid contact with desirable foliage. Contact of spray or mist with fruit is expressly prohibited on the label and is not a legal use of the product. *Gramoxone applications are most effective under cool, cloudy conditions when drying time is slow and uptake into target foliage is optimal.

Comments: *Gramoxone is a dangerous poison and can be fatal if swallowed or inhaled. It is harmful if absorbed through the skin and can cause substantial eye injury. Follow all label precautions when mixing and applying. In vineyards where chemical suckering is undesirable, avoid contact with suckers by making a directed application under appropriate environmental conditions or use shielded equipment. Tank mixes with appropriate preemergence herbicides are recommended for broad-spectrum control and residual activity.

34414

POAST

POAST (sethoxydim) - read the label

Signal word: WARNING

Medical emergency: (800) 832-4357

Selected uses: Postemergence control of young annual grasses and suppression or control of perennial grasses in bearing and nonbearing vineyards, but not within 50 days of harvest.

Rate: Apply 1-2.5 pt per acre surface sprayed, depending on the grass species present. Add recommended adjuvant or crop oil concentrate at recommended rates. A maximum of 5 pt per acre sprayed can be applied annually.

Timing: Apply to actively growing grasses at recommended rates before they exceed the recommended growth stages on the label. (Examples: apply 1 pt per acre when foxtail species are less than 8 inches tall; apply 1.5 pt per acre when quackgrass is less than 8 inches tall.) Repeat treatments may be necessary for full season control.

Comments: Spray to obtain thorough coverage of grass foliage, but not to runoff. Observe the 50-day preharvest interval.

34415

RELY

†RELY (glufosinate-ammonium) - read the label

Signal word: WARNING

Medical emergency: (800) 334-7577

Selected uses: Postemergence burndown of all weeds in new or established vineyards and burndown of grapevine suckers up to 12 inches long. †RELY IS NOT REGISTERED FOR USE IN NASSAU AND SUFFOLK COUNTIES IN NEW YORK.

Rate: Apply 3-6 qt per acre surface sprayed. Consult the label for the appropriate rate, which is based on height and species of weeds present. Additional surfactant is not needed.

Timing: Best results are obtained when applications are made to actively growing weeds. Warm temperatures, high humidity, and bright sunlight improve the performance of †Rely. Contacted foliage wilts within days of application, with complete necrosis in 1-2 weeks. Repeat applications may be necessary. For grapevine sucker control, two applications 4 weeks apart at 4 qt/A are recommended when suckers are less than 12 inches long.

Comments: †Rely is primarily a contact herbicide (similar in activity to paraquat) with limited systemic activity. Damage to grapevine tissue is generally localized to contacted areas (burning of suckers or shoot tips in the herbicide application zone). †Rely controls most annual weeds and some biennials and perennials, including burdock, curly dock and wild onion species. Avoid direct spray or drift to desirable vegetation. Avoid contact with green bark on young vines as injury may occur. In vineyards where chemical suckering is undesirable, avoid contact with suckers by making a directed application under appropriate environmental conditions or use shielded equipment. Tank mixes with appropriate preemergence herbicides are recommended for broad-spectrum control and residual activity. †Rely is an older formulation of glufosinate that is being replaced with †Rely 280.

34416

RELY 280

†RELY 280 (glufosinate-ammonium) - read the label

Signal word: WARNING

Medical emergency: (800) 334-7577

Selected uses: Postemergence burndown of all weeds in new or established vineyards. Under 2(ee) recommendation, also for burndown of grapevine suckers up to 12 inches long. †RELY 280 IS NOT REGISTERED FOR USE IN NASSAU AND SUFFOLK COUNTIES IN NEW YORK.

Rate: Apply 48 fluid ounces (0.88 lb. ai/acre) to 82 fluid ounces (1.5 lb. ai/acre) of product per acre. Consult the label for appropriate rate based on weed height and weed species present. Under the 2(ee) recommendation, for grapevine sucker control, two applications approximately 4 weeks apart at 56 fluid ounces (1.02 lb. ai/acre) are recommended when suckers are less than 12 inches long. Do not apply more than 246 fluid ounces product per acre per year. †Rely 280 should be applied in a minimum of 15 gallons of water per acre.

Comments: †Rely 280 is primarily a contact herbicide (similar in activity to paraquat) with limited systemic activity. Damage to grapevine tissue is generally localized to contacted areas (burning of suckers or shoot tips in the herbicide application zone). †Rely 280 controls most annual weeds and some biennials and perennials, including burdock, curly dock and wild onion species. Avoid direct spray or drift to desirable vegetation. Avoid contact with green bark on young vines as injury may occur. In vineyards where chemical suckering is undesirable, avoid contact with suckers by making a directed application under appropriate environmental conditions or use shielded equipment. Tank mixes with appropriate preemergence herbicides are recommended for broad-spectrum control and residual activity.

34417

ROUNDUP, TOUCHDOWN

ROUNDUP (various formulations), TOUCHDOWN (various formulations), others (glyphosate) - read the label

Signal word: CAUTION

Medical emergency: (314) 694-4000, (800) 327-8633

Selected uses: Postemergence systemic control of annual and perennial weeds in bearing and nonbearing vineyards where contact with green grapevine foliage can be avoided.

Rate: Glyphosate products are available in several formulations of varying concentration. Some products list the amount of active ingredient (ai) on the label, others list the acid equivalent (ae).

Use the following table as a guide to determine the appropriate amount of product to use to apply typical rates of the active ingredient glyphosate:

 Product

 Active Ingredient (ai) Per gallon product

 Amount of product to use at typical use rates (fl oz/A)

 1

 lb ai

 1.5

 lb ai

 2

 lb ai

 Original Roundup, ^Roundup Ultra, ^Touchdown

 4 lb (ai)

 32

 48

 64

 ^Roundup UltraMax

 5 lb (ai)

 26

 39

 52

 Touchdown Total

 4.17 lb (ae)

 23

 35

 46

 Touchdown High Tech

 5 lb (ae)

 19

 29

 38

Consult the individual product labels to determine the appropriate rate for use in specific situations. Many perennial weeds require a higher rate of glyphosate than shown on the above table for effective control. Glyphosate is most effective when applied at lower gallonage and higher concentration. Typical vineyard applications are made at about 10 gal/A sprayed. Note maximum allowable gallonage restrictions on product labels. Effective rates are dependent upon many factors including weed species present, growth stage, and environmental factors. Many small annual weeds can be controlled with applications of 0.5-1.0 lb. ai/A glyphosate while many perennial weeds require higher rates for control. Consult product labels for specific rate recommendations and the addition of surfactant. (The ^Roundup Ultra label states not to add a surfactant while the Touchdown High Tech label states 1-2 qt per 100 gal nonionic surfactant of at least 75% active ingredient must be added.) The addition of ammonium sulfate (AMS) may increase the effectiveness of glyphosate products, particularly under hard water conditions, drought conditions, or when tank mixing with residual herbicides. Add dry AMS at 8.5-17 lb per 100 gal or use equivalent rates of liquid AMS.

Timing: Glyphosate applications should not be made when green shoots, canes, or foliage are in the spray zone. Plant growth is inhibited soon after application, followed by foliar chlorosis within several days (depending on temperature and other factors) and complete necrosis within 1-3 weeks. Glyphosate is absorbed by mature foliage and translocated to other plant parts. To avoid injury, applications should be made before the end of grape bloom, or with shielded sprayers or wiper equipment, but not within 14 days of harvest. Optimal application timing information can be found on product labels. Most annual weeds can be controlled any time they are emerged and actively growing. More effective control of perennial weeds is achieved at the flowering or seed head stage of growth. Control of perennial weeds is most effective when glyphosate is applied to mature leaves capable of translocating the herbicide throughout the plant. For control of woody perennials and other hard-to-control perennial weeds, make applications to actively growing weeds as late as legally possible, prior to leaf senescence on the target weeds. Perennial grasses and other actively growing perennial weeds can be controlled with fall applications, which can be made after 100 percent natural grape leaf fall after harvest.

Comments: Glyphosate can be used as a substitute for cultivation in the row middles as described in the Cornell fact sheet, "Managing Vineyard Floors Using No-tillage." Tank mixes with appropriate preemergence herbicides are recommended for broad-spectrum control and residual activity.

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