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AUTHOR
Tim R. Murphy
The University of Georgia
Crop and Soil Sciences

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TABLE OF CONTENTS
  1. Basics of Turfgrass Weed Management
  2. What is a Weed?
  3. Is this plant a weed???
  4. Human beings decide which plant is a Weed!!!
  5. Why are weeds an annual problem?
  6. Turf Weeds
  7. Weed seed survival insured by:
  8. Weeds are prolific seed producers
  9. Nutsedge
  10. Introduced weeds
  11. Factors affecting seed germination
  12. Why control weeds?
  13. Control vs. Eradication
  14. Weeds
  15. Why do we control weeds in turfgrasses?
  16. Turfgrass Weeds
  17. Annual Bluegrass (Poa annua)
  18. Develop A Plan
  19. The Goal
  20. Integrated Weed Management
  21. Preventive Methods
  22. Cultural Methods
  23. Southeast U. S. Turfgrasses
  24. Southeast U. S. Turfgrasses
  25. A Case Study - Oklahoma
  26. Herbicides - Turfgrass Species
  27. Soil Fertility Effects on Weeds
  28. Irrigation
  29. Weeds Favored by High Soil Moisture
  30. Weeds Favored by Low Soil Moisture
  31. Weeds Favored in Compacted Soils
  32. Weeds
  33. Weeds may indicate a nematode problem
  34. Mechanical Methods
  35. Mowing
  36. Weed Species Response to Mowing
  37. Why does mowing control tall-growing weeds?
  38. Why does mowing not control low-growing weeds?
  39. Kentucky Bluegrass
  40. Herbicides
  41. Herbicides
  42. Maintain Healthy Turfgrass
  43. Identify the Weed Problem
  44. Weed Thresholds - ??
  45. Scouting Sites
  46. Scouting Sites
  47. Scouting Sites
  48. When to Scout?
  49. Developing a Weed Management Program



SLIDE CONTENTS
  1. Basics of Turfgrass Weed Management Tim R. Murphy Crop and Soil Sciences The University of Georgia
  2. What is a Weed? A plant out of place A plant whose virtues have yet to be discovered A flower in disguise
  3. Is this plant a weed??? Common ragweed decreases crop yields, allergen Poison ivy skin rashes, fruit consumed by birds Tall fescue desirable turf and forage grass a weed in warm-season turfgrasses
  4. Human beings decide which plant is a WEED!!!!
  5. Why are weeds an annual problem? Seed and vegetative structure dormancy Prolific seed producers Spread of seed
  6. Weed seed survival insured by: Hard seed coat (testa) Deep burial After ripening mechanisms Germination inhibitors
  7. Weeds are prolific seed producers. Seed/Plant Broadleaf plantain 36,000 Lambsquarters >30,000 Crabgrass 53,000 Texas Panicum 23,000 Annual Bluegrass 2,000
  8. Weeds - Nutsedge Spring 43,560 1 ft. Acre X 3,000,000 Plants 4,000,000 Tubers Fall Acre
  9. Introduced weeds Johnsongrass Common lespedeza Crabgrass Broadleaf plantain Water-hyacinth
  10. Factors affecting seed germination Oxygen Light Scarification Temperature Water
  11. Why control weeds?
  12. Control vs. Eradication Control -Process of limiting a weed infestation to a level that is economically or aesthetically beneficial. Eradication -Elimination of all plants and plant parts of weed species from an area.
  13. Weeds Compete with desirable plants for sunlight, moisture and nutrients May exert allelopathic effects Reduce yields or quality of harvested product
  14. Why do we control weeds in turfgrasses?
  15. Turfgrass Weeds Reduce quality - leaf width, shape, color differences Reduce density - outcompete turfgrasses, can lead to erosion Decrease aesthetic value or utility of the turfgrass. - difficult to mow, disrupt uniformity of playing surfaces, safety considerations, attract insects
  16. Develop A Plan Goals Methods Economics Alternatives Benefits
  17. The Goal Establish and maintain a high quality, nearly weed-free turfgrass.
  18. Integrated Weed Management Methods Preventive Cultural Biological not available in turfgrasses Mechanical Herbicides
  19. Preventive Methods State and Federal laws Weed-free seed, sod, sprigs Weed-free topsoil, topdressing Clean equipment Field borders
  20. Cultural Methods Adapted turfgrasses Fertility Cultivation Water management Insect and disease control
  21. Southeast U. S. Turfgrasses
  22. Soil Fertility Effects on Weeds Low N - legumes, mosses, speedwell High P - annual bluegrass High N - common chickweed, ryegrass, annual bluegrass Low soil pH - red sorrel, broomsedge
  23. Weeds Favored by High Soil Moisture Sedges - purple nutsedge, green kyllinga Rushes Annual bluegrass Mosses, algae Alligatorweed Pennywort
  24. Weeds Favored by Low Soil Moisture Prostrate spurge Poorjoe Common lespedeza Prostrate knotweed
  25. Weeds Favored in Compacted Soils Annual bluegrass Goosegrass Prostrate knotweed Common lespedeza Path rush
  26. Weeds may indicate a nematode problem spurges Florida pusley prostrate knotweed
  27. Mechanical Methods Mowing Hand removal
  28. Why does mowing control tall-growing weeds? Reduces apical dominance of main stem Basal buds initiate growth Continued clipping depletes root carbohydrates Prevents weed seed formation
  29. Why does mowing not control low-growing weeds? Primary growing point is located beneath the mower blade.
  30. Kentucky Bluegrass
  31. Herbicides Herbicide a chemical used to control, suppress or kill plants. Preemergence applied before weed seeds germinate Postemergence applied to emerged weeds
  32. Herbicides Turf species vary in tolerance Weed species vary in susceptibility Turfgrass species and weed identification is critical to herbicide selection!!!!
  33. Maintain Healthy Turfgrass Manage the roots to have good shoots Soil testing is a must! Utilize cultural practices (fertility, irrigation, mowing height, etc.) to improve stress tolerance Keep mower blades sharp ! Use the best species and cultivars for your location
  34. Identify the Weed Problem READ textbooks and periodicals Keep a diagnostic tool kit - hand lens, etc. Know the life cycle of the pest (What temp. does a specific weed seed germinate?) Is the weed the cause or effect of the problem? Confirm your diagnosis
  35. Weed Thresholds - ?? Site - putting green, lawn, etc. People - expectations Weed - population dynamics Budget - dollars
  36. Scouting Sites Use zig-zag pattern Make random stops
  37. Scouting Sites Identify weeds and life cycle Record observations by area - ornamental beds - turfgrass areas * front lawn * back lawn
  38. Scouting Sites Record density by species Low - 1 to 10% Medium - 11 to 20% High - > 20%
  39. When to Scout? Mid-winter months - winter weeds Late-April to July - summer weeds Late summer - assess summer program Late spring - assess winter program
  40. Developing a Weed Management Program Prevent weed introduction Properly maintain turfgrasses Identify weeds and learn life cycle Initiate control practices Preventive Cultural Mechanical Herbicides