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September is the Month for Lawn Renovation Erik H. Ervin, Ph.D. Extension Turfgrass Specialist University of Missouri-Columbia The cooler days and nights of September are finally here. Did your lawn make it through the summer unscathed? Chances are that large portions of turf were lost due to disease, insects, drought, shade, traffic and soil compaction, weed competition, or poor soil fertility. All is not lost, fall is the ideal season to renovate and rejuvenate your cool-season (turf-type tall fescue/Kentucky bluegrass/fine fescue) lawn. Depending on the severity of the problem two renovation options and procedures are available. If less than 50% of the lawn area is covered with the desired grass and many of the weeds present cannot be controlled selectively, then complete renovation may be warranted. Complete renovation may involve killing all existing vegetation, core aerating, and reseeding, or it may involve killing all existing vegetation and roto-tilling the soil. Partial renovation is warranted if greater than 50% of your lawn is healthy and covered with the desired grass. The focus of this short article is partial renovation. One note of caution: Rejuvenation of your lawn following the stresses of summer may merely be temporary unless the cause(s) of turf decline are identified and managed the following summer. Partial Renovation If most of your lawn made it through the summer alive, with only small areas of dead or thinned grass, then partial renovation is all that your lawn may need. This process generally involves the introduction of improved varieties of the existing species into the lawn, or the planting of an altogether different species that is better adapted to the conditions particular to one area of the lawn. The following are some problem situations that I witnessed this summer, along with partial renovation tips. · Rhizoctonia brown patch thinning of small areas of turf-type tall fescue. Tall fescue is quite susceptible to this disease which infects during hot (85-95 F), humid, and rainy periods. The most common response of homeowners to the appearance of brown patch symptoms (e.g., the turf turning brown in large irregular patches) is to apply more irrigation; such a response only helps the disease spread. Areas of the lawn with the worst damage are often in low areas where water drains or puddles and in the shade. In the wetter damaged areas consider planting a blend of two to four Kentucky bluegrass varieties. Kentucky bluegrass is not damaged by Rhizoctonia brown patch. In the shadier areas replant a blend of improved turf-type tall fescue varieties. Tall fescue performs better in the shade than Kentucky bluegrass, plus the newer varieties (not Kentucky-31) have improved tolerance to brown patch. The newer turf-type tall fescue varieties are very similar in texture and color to Kentucky bluegrass. In other words, your lawn will maintain its uniform appearance if you mix these two species. · Thinning and death of Kentucky bluegrass lawn areas due to a combination of disease (dollar spot, summer patch) and heat stress. The solution for these areas is to plant a blend of two to four improved turf-type tall fescue varieties. Tall fescue is not damaged by dollar spot or summer patch and it has better heat tolerance than bluegrass. · Thinning and death of tall fescue and/or Kentucky bluegrass in areas of dense shade. The solution is to plant a more shade-tolerant turfgrass species. The most shade tolerant turf species are fine fescues. There are a number of different fine fescue species that are available including: Chewings fescue, hard fescue, creeping red fescue and sheep fescue. Many garden centers have "shade-mixes" available. When shopping for a good shade mix, look for ones with a high proportion of fine fescues. · Infestation of your cool-season lawn with common bermudagrass. Apply glyphosate (Roundupā ) or glufosinate (Finaleā ) to kill the problem bermudagrass. These products will also kill desirable plants. Wait for two weeks and see if any of the bermudagrass begins to re-grow. If so, apply the herbicide again. Wait one more week and plant the desirable turf species (most likely tall fescue) following the steps for partial renovation below. Follow these steps for partial renovation: 1. Remove as much of the dead and decaying vegetation with a power rake (dethatcher) as possible. 2. After vegetation removal, attempt to lower the power rake so that the soil surface is slightly scratched; disrupt the soil surface in this way by making two to three passes. Use of the power rake in this manner should provide narrow slits or open channels for the seed to fall in. 3. Alternatively, core aerate to provide protected regions of moist soil for good seed germination. Power rakes and core aerators are sometimes available from local rental stores. Otherwise, contact a local lawn care or landscaping company for renovation services. 4. Apply a starter fertilizer (i.e., a fertilizer that contains nitrogen (N), phosphorous (P), and potassium (K)) to the area to be seeded. Follow the label directions to determine how much to apply. 5. Broadcast the seed, by hand, applying approximately ½ pound Kentucky bluegrass seed per 100 square feet or 1 pound tall fescue or fine fescue seed per 100 square feet. (Note: Always purchase high quality seed. Check the seed label for the following standards: the seed must be less than one year old; all varieties should be named and their state of origin listed; the listed germination should be > 85%; the bag should contain no noxious weeds or "other crop" and less than 1% weed seed.) 6. Rake the seed into the slits or aeration holes to improve seed/soil contact and cover the area with a thin layer of mulch (e.g., straw, shredded leaves, quality compost) to maintain adequate moisture during germination. 7. Water frequently enough to keep the soil moist, but not so much as to cause puddles. 8. Begin weekly mowing once the grass has reached a height of three inches. 9. As the seedlings mature, begin watering in a manner similar to the rest of the lawn, deeply, but less frequently. 10. Remove any weeds by hand. 11. In late October apply a "winterizer" fertilizer to the whole lawn. 12. In early April, apply a preemergence herbicide to the whole lawn to prevent crabgrass and goosegrass invasion. 13. In late April, apply a 2,4-D herbicide to control broadleaf weeds, if needed.
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