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Master Gardener Training - Weed Identification and Management

Master Gardener Training - Weed Identification and Management. Jeffrey Derr Professor of Weed Science Virginia Tech. Additional information - Weed identification Books. Weeds of the Northeast – Cornell Press Weeds of Southern Turfgrass, Georgia Cooperative Extension Service

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Master Gardener Training - Weed Identification and Management

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  1. Master Gardener Training - Weed Identification and Management Jeffrey Derr Professor of Weed Science Virginia Tech

  2. Additional information- Weed identification Books • Weeds of the Northeast – Cornell Press • Weeds of Southern Turfgrass, Georgia Cooperative Extension Service • Weeds of the South - University of Georgia Press • Color Atlas of Turfgrass Weeds – John Wiley & Sons

  3. Additional information • Pest Management Guides Home Grounds and Animals http://pubs.ext.vt.edu/456/456-018/456-018.html • Herbicide labels

  4. Additional Information – Weed ID Websites Virginia Tech Weed ID websites www.ppws.vt.edu/ipm/weeds_container_nurseries.html www.turfweeds.net www.ppws.vt.edu/weedindex.htm

  5. What is a weed?

  6. Prickly pear cactus Purple loosestrife

  7. What is a weed? Plant out of place, growing were it is not needed or wanted • Purple loosestrife (Lythrum) • Prickly pear cactus • Bamboo • English ivy

  8. Why control weeds?

  9. Reasons to Manage Weeds Competition - leading to reduced crop growth and yield (quantity, quality) • for water (drought years) • nutrients (especially nitrogen) –cannot correct with extra N • light (viny weeds) • pollination (dandelion blooms) – reduced crop pollination)

  10. Reasons to Manage Weeds • Harbor insect and disease pests (dandelion and tomato ringspot virus, buckhorn plantain/aphids) • Attract bees (problem for those allergic to bee stings) • Interfere with harvest (rash - poison ivy, spines - brambles) • Allelopathy (natural herbicides) - juglone – black walnut • Provide cover for rodents

  11. Reasons to manage weeds • Adversely affect human health – rashes (poison ivy), poisonous if eaten (black nightshade), allergies (common ragweed), thorns (greenbrier) • Reduce aesthetic value of lawns and gardens • Block visibility along highways • Block water flow in ditches

  12. Weed names • Common names – differ across state, country (stickweed, wiregrass, silver crabgrass, etc.) Weed scientists used an approved list of common names for the US (horseweed, bermudagrass, goosegrass) • Scientific name – used throughout the world Eleusine indica (goosegrass)

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

  14. Summer annual grasses Large crabgrass Goosegrass Giant foxtail

  15. Microstegium (Japanese stiltgrass)

  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. 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. False Green Kyllinga – perennial sedge

  25. Other monocots Wild garlic (perennial)

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

  27. Simple perennial broadleaves Dandelion Buckhorn plantain

  28. Creeping perennial broadleaves Poison ivy Horsenettle Hedge bindweed

  29. Perennial broadleaf weeds Hemp dogbane Black locust

  30. Turf Weed Control • Biological – none available • Cultural • Chemical

  31. Integrated Pest Management Determine management level – high, medium, low Scouting – identify weed problems late spring for winter annuals late summer for summer annuals, perennials Determine weed infestation level/need for renovation Evaluate control options – nonchemical vs chemical Chemical treatments – broadcast, spot-treatment

  32. Cultural Control of Weeds in Turf Use the best adapted turf species for the site Proper mowing heights : 3-4 inches for tall fescue Maintain appropriate pH, nutrient levels, irrigation Correct compaction, shade, and drainage problems Control insects and diseases Reduce stress – drought, excess salts, etc.

  33. Biorational Products for TurfCorn gluten • By-product of corn milling • 60% protein • Preemergence herbicide • Annual weed control, esp crabgrass • No postemergence effects • ~ 10% nitrogen • Herbicidal components • Various products Safe Lawn, WOW!, A-Maize-N, Organic Weed and Feed, etc

  34. Chemical Control in Turf • Preemergence herbicides – primarily for annual weeds • Postemergence herbicides – primarily used for perennial weeds

  35. Crabgrass control in turf Preemergence Pre + Pre Postemergence Pre + Post

  36. Preemergence Crabgrass Herbicides – at seeding or newly-seeded cool-season turf Tupersan (siduron) Tenacity (mesotrione) – best applied by a lawn care company Drive (quinclorac) – certain formulations are for commercial applicators only

  37. Preemergence Crabgrass Herbicides – established cool-season turf Barricade (prodiamine) Dimension (dithiopyr) pendimethalin (Halts, Pre-M, Pendulum, etc.) bensulide (Bensumec, etc.) Team (trifluralin + benefin) Dacthal (DCPA) Balan (benefin) Tupersan (siduron)

  38. Preemergence Crabgrass Herbicides – established warm-season turf Barricade (prodiamine) Dimension (dithiopyr) pendimethalin (Halts, Pre-M, Pendulum, etc.) bensulide (Bensumec, etc.) Team (trifluralin + benefin) Dacthal (DCPA) Balan (benefin)

  39. Postemergence crabgrass herbicides – cool seasonturf Dimension (pre-tillering of crabgrass) Drive/products containing quinclorac Acclaim Extra (fenoxaprop) Tenacity (mesotrione)

  40. Annual Bluegrass control • Preemergence crabgrass herbicide in late August (probably will not be able to overseed) • No postemergence controls for homeowners

  41. Preemergence Controlof Annual Broadleaf Weeds Depends upon the herbicide Preemergence control possible for: Spotted (Prostrate) spurge Common chickweed Henbit Others

  42. Preemergence broadleaf control Gallery, Green Light Portrait (isoxaben) Preemergence crabgrass herbicides

  43. Bermudagrass Suppression in Tall fescue • Suppression/Need repeat treatments • Acclaim Extra + Turflon, some other chemicals • Or 2-3 applications of Roundup and reseed • Proper mowing height • Overseeding

  44. Yellow nutsedge control in Cool-season turf • Postemergence control • SedgeHammer • Dismiss • Basagran • Also used for kyllinga control

  45. Wild Onion, Wild Garlic Control 2,4-D ester

  46. Broadleaf Control Chemicals 2,4-D, 2,4-DP, MCPP, MCPA, dicamba, triclopyr, clopyralid, fluroxypyr • Usually use combinations such as • 2,4-D + MCPP • 2,4-D + MCPP + dicamba • Leaf, root absorbed • Sprays and granular forms

  47. Spray versus Granular application • Spray generally provides better control since these chemicals are absorbed by leaves as well as roots • Granular formulations – reduce potential for leaf uptake, apply when dew is present • Granules – no spray drift, still can injure ornamentals through root uptake

  48. Dandelion Buckhorn plantain

  49. Oxalis (woodsorrel)

  50. Ground ivy Triclopyr or a dicamba based product

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