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

2. 2014 Pest Management Guides
Horticultural and Forest Crops
Weed control section for grapes

3. Weed identification Books and Websites
Weeds of the Northeast – Cornell Press
Weeds of the South - University of Georgia Press
Virginia Tech weed identification website:

4. 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

5. 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

6. 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

7. 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.

8. 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

9. 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

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

11. 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

12. 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

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

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

15. Summer annual grasses
Large crabgrass
Goosegrass
Giant foxtail

16. Winter annual grasses
Italian (Annual) ryegrass Annual bluegrass

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

18. Summer annual broadleaves
Common ragweed tall morningglory
Common lambsquarters Smooth pigweed

19. Winter annual broadleaves
Vetch
Henbit
Common chickweed
Horseweed

20. Biennials
Musk thistle Wild carrot

21. 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

22. Perennial grasses
Johnsongrass
Quackgrass
Bermudagrass

23. Yellow and Purple Nutsedge
Perennial sedges (rhizomes, tubers)

24. Other monocots
Wild garlic (perennial)

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

26. Simple perennial broadleaves
Dandelion Buckhorn plantain

27. Creeping perennial broadleaves
Poison ivy Horsenettle
Hedge bindweed

28. Perennial broadleaf weeds
Hemp dogbane Black locust

29. Grape Weed Control
Biological – little available
Cultural
Chemical

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

31. 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

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

33. 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

34. 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

35. 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

36. 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

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

38. 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

39. 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

40. 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

41. 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.

42. 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.

43. 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

44. 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

45. 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

46. 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

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

48. 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)

49. 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

50. Postemergence herbicides for grapes

51. 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)

52. 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

53. 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

54. 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

55. 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

56. 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

57. 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

58. 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

59. 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

60. Horseweed (Conyza canadensis)

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

62. Cutleaf evening primrose
Dayflower
White clover