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.

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

AnnualsSummer - grass, broadleaf, sedge, other

monocotsWinter – grass, broadleaf

Biennials – broadleaf

Perennials – grass, sedge, other monocots, broadleaves

Summer annual grasses

Large crabgrass

Giant foxtail

Goosegrass

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

Common chickweed Horseweed

Henbit

Biennials

Musk thistle Wild carrot

Perennial Monocots

Perennial grasses• clump - tall fescue, orchardgrass• creeping - quackgrass, bermudagrass,

johnsongrass

Perennial sedges – yellow nutsedge

Other perennial monocots – wild garlic

Bermudagrass

Perennial grasses

Quackgrass

Johnsongrass

Yellow and Purple NutsedgePerennial sedges (rhizomes, tubers)

Other monocots

Wild garlic (perennial)

Perennial broadleaves

• Simple – dandelion, buckhorn plantain

• Creeping - bindweed, brambles, poison ivy, horsenettle, hemp dogbane

Dandelion Buckhorn plantain

Simple perennial broadleaves

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 PreparationGoal 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 controlPreemergence 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, bittercressBuckhorn 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 controlPostemergence 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)

Nonselectiveparaquat (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)

NonselectiveScythe (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)

NonselectiveGlyphosate (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

Dayflower

Cutleaf evening primrose

White clover