Rehabbing troubled lawns 9 23-10


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  • First step in rehabbing troubled turf is to identify the cause of damaged or thinned turf. One or more of these conditions may exist.
  • Once the cause of turf decline is identified, select a turf improvement program that will best upgrade the turf by taking into consideration the existing conditions and the desired turf quality.
  • Leaf shredding on ryegrass due to a dull or poorly adjusted blade. Before ryegrass, shredding was a minor problem.
  • Perennial ryegrass looks good when mowed between 1.5 and 2.5 inches. It can tolerate mowing as low as .75”, but is rapidly invaded and dominated by other grasses such as bentgrass and annual bluegrass. Golf course fairways planted with ryegrass and mowed at 0.5” will quickly convert to annual bluegrass.
  • Mowing an erect growing grass low drastically reduces the leaf surface area of individual shoots.
  • Catch Can Test
  • Turf Nutrition
  • When nitrogen is applied in the ammonium form during late fall or early winter, it stays in the ammonium form because temperatures are too cold for nitrification to occur. In the mild winter areas west of the Cascade Mountains, the result is dark green turf all winter because of the nitrogen effect on chlorophyll content and the fact that growth is slow due to cold temperatures so mowing doesn’t remove much nitrogen. Grass growing under low nitrogen in fall will go off color rapidly in fall and leave you with a brown lawn all winter long. This is apparent in the unfertilized plot in this trial.
  • It is hard to get good seed to soil contact with no till renovation techniques. One way to get better uniformity and insure rapid germination is to apply a mulch. I always try to mulch renovated sites.
  • If you have a good grade but want to put in a different grass, a complete renovation is sometimes the best way to go. If you just want to bolster the existing turf, you can use a partial renovation.
  • If you do everything right, it doesn’t matter much what technique you use for planting a new lawn or renovating an old one.
  • Most grasses are very responsive to nitrogen. When nitrogen fertilizer is applied the grass soon develops dark green color as chlorophyll content increases. Shoot growth rate increases and there may be an increase in the number of green leaves per shoot. Over all turf looks dense and green. Provided water is not limiting vertical growth rate increases, which means you have to mow regularly to keep the lawn under control.
  • Rehabbing troubled lawns 9 23-10

    1. 1. “ Rehabbing Troubled Lawns” Rob Golembiewski, Ph.D. OSU Oregon State University
    2. 7. Reasons for Turfgrass Failure <ul><li>Improper cultural practices </li></ul><ul><li>Drought, heat, or cold stresses </li></ul><ul><li>Weeds, insects, or diseases </li></ul><ul><li>Excessive thatch </li></ul><ul><li>Unfavorable growth environment (shade, poor soil conditions) </li></ul><ul><li>General neglect, abuse, or overuse </li></ul>
    3. 8. Turf Improvement Programs <ul><li>1. Initiate a program of sound cultural practices </li></ul><ul><li>2. Renovate turf by planting into existing live or dead vegetation </li></ul><ul><li>3. Totally reestablish the turf area </li></ul>
    4. 9. Assessment <ul><li>Turfgrasses present </li></ul><ul><li>Soil conditions (fertility, pH, and drainage/aeration) </li></ul><ul><li>Thatch levels </li></ul><ul><li>Environmental conditions (light quanity, quality, and duration) </li></ul><ul><li>Existing perennial grassy weeds </li></ul>
    5. 10. Program 1 - Sound Cultural Practices <ul><li>Turf has many acceptable characteristics, but in undesirable condition </li></ul><ul><li>Turf areas brought to acceptable quality by altering turf management practices </li></ul>
    6. 11. Successful Program <ul><li>Existing turf must have: </li></ul><ul><li>acceptable turf species/cultivar </li></ul><ul><li>adequate density (potential for) </li></ul><ul><li>acceptable soil conditions </li></ul><ul><li>thatch level of ½” or less </li></ul><ul><li>small number of perennial grassy weeds </li></ul>
    7. 12. Implementation <ul><li>Integrate the following practices to bring turf into desired condition: </li></ul><ul><li>mowing </li></ul><ul><li>irrigation </li></ul><ul><li>fertilization </li></ul><ul><li>cultivation </li></ul><ul><li>pest control practices </li></ul>
    8. 15. 0.5” 1.0” 1.5”
    9. 16. .5” 1.5”
    10. 17. 0.5” 1.0” 2.0”
    11. 22. Unfertilized Balanced NPK + Fe Balanced NPK
    12. 30. Program 2 – Partial Renovation <ul><li>Often, poor turf requires more than improved cultural practices </li></ul><ul><li>Planting new seed into existing live or dead turf provides better turf appearance, density, disease/insect resistance, wear tolerance, and shade/drought tolerance </li></ul>
    13. 31. Successful Program <ul><li>Should have proper: </li></ul><ul><li>soil drainage/aeration </li></ul><ul><li>pH </li></ul><ul><li>fertility </li></ul><ul><li>thatch levels less than ¾” </li></ul><ul><li>small number of perennial grassy weeds </li></ul><ul><li>if large number, apply nonselective herbicide </li></ul>
    14. 32. Implementation <ul><li>1a. Overseeding into </li></ul><ul><li>live turf, mow short </li></ul><ul><li>and remove debris </li></ul><ul><li>to reduce canopy </li></ul><ul><ul><li>competition for </li></ul></ul><ul><ul><li>germinating seeds </li></ul></ul><ul><li>1b. Overseeding into dead turf, use nonselective </li></ul><ul><li>herbicide to kill vegetation then mow to </li></ul><ul><li>remove debris </li></ul>
    15. 33. Implementation <ul><li>2. Open soil to enhance seed-soil contact via: </li></ul><ul><ul><li>hand raking </li></ul></ul><ul><ul><li>vertical mowing </li></ul></ul><ul><ul><li>core aerification </li></ul></ul><ul><ul><li>slit seeding </li></ul></ul><ul><li>3. If not slit seeding, broadcast seed </li></ul>
    16. 34. Vertical Mowing <ul><li>1. Rotating blades physically extract thatch. </li></ul><ul><li>2. Blades should be set 1/8 to 1/4” soil depth. </li></ul><ul><li>3. Traverse area in at least 2 directions or until 30% of soil is exposed. </li></ul><ul><li>4. Seed applied by broadcasting </li></ul><ul><li>or slit-seeding. </li></ul>
    17. 35. Core Cultivation <ul><li>1. Hollow cylinder cones mechanically forced down into turf and soil plug is removed. </li></ul><ul><li>2. Removal of cores </li></ul><ul><li>exposes soil which </li></ul><ul><li>provides a mean for </li></ul><ul><li>seed-soil contact. </li></ul><ul><li>3. Seed usually applied </li></ul><ul><li>by broadcasting. </li></ul>
    18. 36. Slit Seeding <ul><li>1. Disk-like device slits the turf and seed is deposited. </li></ul><ul><li>2. Method most effective for obtaining good seed-soil contact. </li></ul><ul><li>3. Should be done minimally in 2 directions for effective coverage. </li></ul>
    19. 37. Broadcast Seeding <ul><li>1. Not very successful method for good germination. </li></ul><ul><li>2. Spreading seed on a non-renovated turf results in little seed-soil contact. </li></ul>
    20. 39. Implementation <ul><li>4. Incorporate seed with a drag mat or rake </li></ul><ul><li>5. Mulch </li></ul><ul><li>6. Irrigate daily until </li></ul><ul><li>germination complete </li></ul><ul><li>7. Mow once turf at </li></ul><ul><li>intended height of </li></ul><ul><li>cut </li></ul>
    21. 40. Program 3 – Complete Renovation <ul><li>Sometimes turf so poor or the environment is unsuitable to support turf growth </li></ul>
    22. 41. Successful Program <ul><li>This drastic method necessary when: </li></ul><ul><li>soil conditions unsuitable to sustain turf growth </li></ul><ul><li>thatch levels greater than ¾” and uncontrollable </li></ul><ul><li>existing vegetation unacceptable and can’t be improved </li></ul>
    23. 42. Implementation <ul><li>1. Use a non-selective, short residual herbicide like glyphosate (Roundup) or glufosinate (Finale) to kill existing turf and weeds </li></ul><ul><li>*Effectiveness of herbicides enhanced by: </li></ul><ul><li>a. Skipping a mowing prior to treatment </li></ul><ul><li>b. Apply to actively growing </li></ul><ul><li> turf </li></ul>
    24. 43. Implementation <ul><li>2. Correct soil pH, drainage, and/or fertility problems by properly preparing the planting bed </li></ul><ul><li>3. Seeding or sodding can be initiated 3-5 days after treatment with non-selective herbicides </li></ul>
    25. 44. Post-Renovation Care <ul><li>Once renovated turf has been seeded, turf </li></ul><ul><li>should be maintained as if it was a newly </li></ul><ul><li>established turf </li></ul>
    26. 45. Complete renovation: Kill/dethatch/reseed Partial renovation: Dethatch/overseed
    27. 46. 17 days after planting Sod Seed Dethatched Seed Killed/dethatched
    28. 47. Summary 1. When turf unacceptable, determine reason for decline, select and implement program for upgrading turf 2. After turf improved, maintain sound turf management program
    29. 49. Contact Information <ul><li>Rob Golembiewski </li></ul><ul><li>Oregon State University </li></ul><ul><li>4017 ALS Building </li></ul><ul><li>Corvallis, OR 97331 </li></ul><ul><li>Phone: (541) 737-5449 </li></ul><ul><li>Email: [email_address] </li></ul>