Weed and Vegetation Management in Grape Production Jeffrey Derr Professor of Weed Science Virginia Tech Charlottesville VVA talk 1/30/14

2014 Pest Management Guides Horticultural and Forest Crops http://pubs.ext.vt.edu/456/456-017/456-017.html Weed control section for grapes http://pubs.ext.vt.edu/456/456-017/Section-3_Grapes-3.pdf

Weed identification Books and Websites Weeds of the Northeast – Cornell Press Weeds of the South - University of Georgia Press Virginia Tech weed identification website: http://oak.ppws.vt.edu/weedindex.htm

Vegetation Management Plan Cover crop between the rows - Erosion control, ability to drive through vineyard soon after a rain Initially bare ground within the grape row - weeds, cover crops suppress vine growth

Weed control in row middles Few options after planting grapes Aim (carfentrazone) -contact herbicide that will control small annual broadleaf weeds. Establish cover crop, control broadleaf weeds, kill cover crops in strips prior to planting

Perennial Cover Crop Evaluation for Enhanced Vineyard Floor Management Funded by the Virginia Wine Board/ VVA/VDACS Trials in Virginia Beach, Blacksburg, and cooperating vineyards Evaluate cool- and warm-season perennial grasses for use between rows of grapes

Project Goals Evaluate ease of establishment and persistence for cool- and warm-season cover crops between vine rows. Evaluate weed suppression for each perennial cover crop. Determine crop suitability criteria such as: traffic, drought, and cold tolerance, as well as maintenance requirements. Evaluate cover crop influence on overall soil health. Cover crops are an essential tool for a sustainable approach to vineyard floor management. Proper cover crop selection can help decrease herbicide use and mowing costs, as well as improve overall soil health.

Cool-season Establishment - Blacksburg All good establishment ‘Bighorn GT’ Sheep /Hard Fescue ‘DTT-43’ Dwarf Tall Fescue ‘DTT-20’ Dwarf Tall Fescue ‘Rough and Ready’ Microclover mix* ‘Companion Grass ‘ Cover Crop Mixture** ‘Applaud’ Perennial Ryegrass ‘Fawn’ K31 ‘Midnight’ Kentucky Bluegrass ‘Silverlawn’ Creeping Red Fescue

Cool-season Establishment - Blacksburg ‘Rough and Ready’ Microclover mix* - 34% Quatro Sheep Fescue, 30% Eureka II Hard Fescue, 30% PR8821 Perennial Ryegrass, 5 % Microclover ‘Companion Grass ‘ Cover Crop Mixture** -   80% PR8821 Perennial Ryegrass, 20% Creeping Red Fescue

Warm-season Establishment - Blacksburg Poor with blue grama Uneven with bermudagrass, zoysiagrass and their combinations with cool-season grasses - Weed competition

Establishment – Virginia Beach Good – tall fescues (Fawn, DTT 43, DTT 20, Justice), zoysiagrass + Gotham hard fescue Poor – Kentucky bluegrass, hybrid bluegrass, Bighorn GT, Companion grass, Rough and Ready, Perennial ryegrass, zoysia + perennial; ryegrass, blue grama

Traffic tolerance Good with the tall fescues, Companion grass, Rough and Ready Fair with Kentucky bluegrass Poor to fair with Bighorn GT, creeping red fescue

Cover crops – Cool-season glyphosate tolerant Big Horn GT – sheeps fescue Aurora Gold hard fescue Compared to Gotham hard fescue

Weed life cycle Annuals Summer - grass, broadleaf, sedge, other monocots Winter – grass, broadleaf Biennials – broadleaf Perennials – grass, sedge, other monocots, broadleaves

Summer annual grasses Large crabgrass Goosegrass Giant foxtail

Winter annual grasses Italian (Annual) ryegrass Annual bluegrass

Annual broadleaves Summer common lambsquarters, smooth pigweed, common ragweed, ivyleaf morningglory Winter vetch, horseweed, fleabane, common chickweed, henbit

Summer annual broadleaves Common ragweed tall morningglory Common lambsquarters Smooth pigweed

Winter annual broadleaves Vetch Henbit Common chickweed Horseweed

Biennials Musk thistle Wild carrot

clump - tall fescue, orchardgrass Perennial Monocots Perennial grasses clump - tall fescue, orchardgrass creeping - quackgrass, bermudagrass, johnsongrass Perennial sedges – yellow nutsedge Other perennial monocots – wild garlic

Perennial grasses Johnsongrass Quackgrass Bermudagrass

Yellow and Purple Nutsedge Perennial sedges (rhizomes, tubers)

Other monocots Wild garlic (perennial)

Perennial broadleaves Simple – dandelion, buckhorn plantain Creeping - bindweed, brambles, poison ivy, horsenettle, hemp dogbane

Simple perennial broadleaves Dandelion Buckhorn plantain

Creeping perennial broadleaves Poison ivy Horsenettle Hedge bindweed

Perennial broadleaf weeds Hemp dogbane Black locust

Grape Weed Control Biological – little available Cultural Chemical

Vegetation Management Plan Killed strip within the row to reduce weed competition Mowed (grass) alleyways for erosion control, drivability soon after rain

Site Preparation Goal is to reduce weed populations, especially for perennial weeds Cover crops - cropping with competitive or allelopathic crops, such as rye or sudangrass, for 1 to 2 to two years before planting Grow alternative crops like corn where troublesome weeds like yellow nutsedge or broadleaf weeds can be controlled using herbicides that cannot be used in fruit. Establish permanent cover

Site prep - Chemical control Glyphosate - apply in strips in fall for fescue, orchardgrass control - plant into killed strips

Cultural control Cultivation (mechanical) – suppress perennials, break crusts, soil erosion, root damage Cultivation (flame) – tree injury, fire hazard Black plastic, fabrics – habitat for rodents, cost Organic mulches – improve moisture penetration, habitat for rodents, cost

Chemical control Preemergence herbicides Match to weed problems Apply prior to weed germination (clean soil or add a postemergence) Apply proper rate for soil type (organic matter, soil texture) Need rain or irrigation for activation Shorter residual under wet conditions

Preemergence herbicides for grapes – annual grasses and small-seeded broadleaf weeds Surflan (oryzalin), Prowl (pendimethalin), Devrinol (napropamide) – annual grasses, some broadleaves Can be used at planting after soil settles

Preemergence control – small-seeded broadleaf weeds Trellis (Gallery) (isoxaben) Combine with Surflan (oryzalin), Prowl (pendimethalin), Devrinol (napropamide) – annual grasses, some broadleaves Can be used at planting after soil settles 165 day PHI

Preemergence herbicides for grapes – annual grasses, small-seeded broadleaf weeds, suppression of yellow nutsedge Solicam (norflurazon) Vines must be established 2 years

Pre and early POST control – annual grasses, small-seeded broadleaf weeds, suppression of yellow nutsedge, dandelion Matrix (rimsulfuron) Vines must be established 1 year Short residual Combined with Surflan, Prowl, etc. for broader-spectrum control 14 day PHI

Pre and early Post control – annual broadleaf weeds, annual grasses Goal, GoalTender (oxyfluorfen) vines established 3 years unless on trellis wire at least 3 feet above soil surface combine with Surflan, Prowl, etc. for improved annual grass control

Chateau (flumioxazin) – grapes Dormant applications preferred Treat in early spring and fall Could add a preemergence grass herbicide, especially under high annual grass pressure or lower rates Add a postemergence herbicide for control of emerged weeds Use directed sprays, do not apply overtop of grapes

Chateau (flumioxazin) – grapes 6 to 12 ounces of product per treated acre, which equates to 0.19 to 0.38 pounds active ingredient per acre. Maximum use rate per year is 24 ounces of product. Use of 6 ounces of Chateau per acre when applications are made to very sandy/gravelly soils and tree or grape vines are established less than 3 years.

Pre and early Post control – annual broadleaf weeds, annual grasses Chateau (flumioxazin) Vines established at least 2 years unless vines protected with grow tubes, waxed containers, etc.

Results withChateau Strength is annual broadleaf control Excellent control – common lambsquarters, pigweed, velvetleaf, jimsonweed, common ragweed, prickly sida, bittercress Buckhorn plantain, yellow woodsorrel from seed Good control – annual morningglories, cocklebur

Results with Chateau Fair to excellent control of annual grasses: Large crabgrass, yellow foxtail, giant foxtail, johnsongrass from seed No control of yellow nutsedge or bermudagrass at use rates

Preemergence control - annual broadleaf weeds, annual grasses Princep (simazine), Karmex (diuron) Vines established 3 years Inexpensive broadleaf control Match rate to soil type Combine with a grass herbicide

Preemergence herbicides for grapes – winter applied – cool-season grasses, winter annuals Kerb, Casoron – winter-applied, cools season perennial grasses, winter annuals For control of quackgrass, tall fescue, orchardgrass, plus winter annuals

Pre – annual grasses, annual broadleaf weeds Alion (indaziflam) Vines established at least 5 years

Alion (indaziflam) -sprayable form 1.67 lb/gal caution label Preemergence with significant post activity different mode of action (cellulose biosynthesis inhibitor) -directed spray -use rate 5 fl oz/acre (0.065 lb ai/A) (only 1 appl/year at that rate)

Alion (indaziflam) Strength – controls annual grasses (crabgrass, goosegrass, foxtails, annual bluegrass, annual ryegrass) many annual broadleaf weeds (jimsonweed, pigweed, horseweed, lambsquarters, velvetleaf, eclipta, spurge, henbit, chickweed, speedwell, bittercress) Long residual Weakness Does not control morningglory or yellow nutsedge

Postemergence herbicides for grapes

Chemical control Postemergence herbicides Match to weed problem Apply to actively growing weeds (no drought stress) Apply under warm temperatures (60 – 85 F) See if a surfactant is needed (nonionic versus crop oils)

Postemergence Grass herbicides Perennial grasses – johnsongrass, quackgrass, bermudagrass Annual grasses – crabgrass, foxtails, etc. Poast (sethoxydim), Fusilade DX (fluazifop) – 50 day PHI Select Max – nonbearing Add a nonionic surfactant or crop oil

Aim (Carfentrazone) a 1.9 lb/gallon EW or as a 2 lb/gallon EC postemergence control of small annual broadleaf weeds. 1 to 2 fluid ounces per acre. Apply when annual broadleaf weeds are less than 6 inches in height and actively growing. does not control grasses. can be tank mixed within other postemergence herbicides for broader-spectrum control or with preemergence herbicides. Adding a crop oil concentrate or nonionic surfactant may improve weed control. Do not allow spray to contact green stems, leaves, flowers Can also be used for control of suckers – see label for rates and directions for this use. 3 day PHI

Rely (glufosinate) Nonselective Contact with some translocation Less effective on perennial weeds than glyphosate but lower risk of crop injury Apply as a directed spray when weeds are small and actively growing 14 day PHI

Alternatives to Rely (glufosinate) Nonselective paraquat (Gramoxone) Rapid acting contact No effect on underground tissue – rhizomes, roots, bulbs, etc. Restricted use due to toxicity Apply this contact herbicide as a directed spray when weeds are small and actively growing

Alternatives to Rely (glufosinate) Nonselective Scythe (pelargonic acid) Acetic acid (Weed Pharm) – organic production Rapid acting contact No effect on underground tissue – rhizomes, roots, bulbs, etc. sucker control

Alternatives to Rely (glufosinate) Nonselective Glyphosate (Roundup, others) more effective on weeds (systemic) but poses greater risk of systemic damage apply using a shield spray or wiper application Keep off grape foliage, green stems 14 day PHI

Glyphosate Off patent, available under a variety of trade names (Roundup WEATHERMAX, Touchdown, etc.) Check label for pounds glyphosate acid/gallon Check label for need for a surfactant Check spray water for calcium content (hard water) – add ammonium sulfate 8-17 lb/100 gal

Herbicide Resistance Refers to a weed that used to be controlled but no longer is controlled Separate from tolerance where a weed species was always hard to control with that herbicide

Horseweed (Conyza canadensis)

Weed shifts (Weeds less sensitive to glyphosate) Bengal dayflower/tropical spiderwort Doveweed Dayflower Morningglory

Cutleaf evening primrose Dayflower White clover