Horticulture : News
DATE: July 27, 2010
HARDIN COUNTY COOPERATIVE EXTENSION SERVICE
201 Peterson Drive
Elizabethtown, Kentucky 42701-9370
BY: Amy Aldenderfer
County Extension Agent for Horticulture
Lawns- Parched or Killed
I\For much of Kentucky the drought, heat and irrigation restrictions have been severe enough to seriously injure or kill many, many home lawns. A lot of people believe that Kentucky bluegrass and tall fescue lawns will just become dormant (brown) and then recover when cool nights and good rainfall occur. Unfortunately this is not usually the case when the heat and drought is as severe as it has recently been in many parts of Kentucky.
To determine the extent of injury, consider the following:
(1)When lawns go completely brown, with little or no green leaves showing, you can expect kill or severe thinning of the grass.
(2) Kentucky bluegrass is more quickly injured than tall fescue but both grasses may die. Although tall fescue is more heat and drought tolerant than Kentucky bluegrass, it usually is growing on poorer soils and it has few underground tillers to aid recovery. Also, because of the heat and humidity this summer, brown patch disease has been an extra stress on most tall fescue lawns. Perennial ryegrass lawns will seldom survive such heat and drought, but bermudagrass and zoysiagrass lawns should have no problem. Fine fescue growing in semi- shady locations will usually become dormant and recover before the following spring.
(3) Low maintenance lawns that have a mixture of turfgrasses and weeds, and/or lawns that almost never get fertilized with Nitrogen, will usually recover. They certainly won't get better, but you will not likely need to reseed.
(4) Almost never will the complete lawn die. Portions of the lawn that have good soil, protected by moderate shade and north facing slopes are more likely to survive.
(5) Proper irrigation will greatly aid the lawn during very dry weather. However, if the lawn is over-watered and then suddenly the water is cut-off (during the heat and drought); that lawn is usually doomed. When this type of lawn turns brown, make plans to reseed.
(6) Very sandy and heavy clay lawns suffer the most damage.
(7) The longer the heat and drought, the more the damage. Unfortunately one cannot look at the lawn or closely examine individual grass plants and positively determine if it is alive or dead. Even when a lawn does recover, it may be October or November before one can tell for sure how much turf has been lost and how bad renovation is needed.
It is obvious that hundreds of lawns throughout Kentucky will need renovation this fall. Consider the following:
---Tall fescue is much easier to establish from seed than is Kentucky bluegrass. To get good establishment of Kentucky bluegrass, a conventional seedbed is usually necessary. Tall fescue can be established using a conventional seedbed or by slit (no-till) seeding.
---Timing is critical. The optimum timing for Kentucky is mid August through September, and no later than October 15.
However, one should not consider seeding until a good, soaking rainfall has occurred and the drought is officially `over'.
---The heat and drought has greatly increased the growth of crabgrass but a heavy crabgrass population is not usually a problem when renovating a lawn in the fall with tall fescue. The summer increase of perennial grassy weeds such as bermudagrass, nimblewill and dallisgrass is however, a serious problem. These need to be sprayed with RoundUp at least a few days prior to seeding; however you will not get good control of the perennial weeds unless the proper rate of RoundUp is applied and these grasses have enough soil moisture that they are actively growing.
Especially for bermudagrass, spray as soon as soil moisture is adequate to get good growth, then wait about 3-4 weeks and spray again with RoundUp. Removing the dying sod a few days after the first spray will help encourage escaped, underground bermudagrass to re-grow; then the second spray will be more effective. With only one spray on bermudagrass, expect only 80- 90 % control.
Dense areas of living Kentucky bluegrass will also deter tall fescue establishment. To truly get a mono-stand of tall fescue and quality turf, thick areas of Kentucky bluegrass should likewise be sprayed with Roundup a few days before renovation. If the lawn is truly devastated by the heat and drought, and perennial grassy weeds are not prevalent, certainly you can omit the Roundup.
---Seed about 5-6 pounds of tall fescue per 1000 sq. ft. of lawn. If using a slit seeder, a machine that slices through the thatch and drops the seed into the slits, apply about one pound of seed per 1000 sq. ft. for each pass. If you go over the lawn two times, then you would want to also broadcast about 3 pounds per 1000 sq ft before the last pass with the slit seeder. Just broadcasting the seed, without some surface disturbance / preparation, will result in almost no soil-seed contact and poor survival.
Traditional dethatching equipment can be rented at most rental agencies. With the knives set to penetrate through the thatch and about 1/4th inch into the soil, go over the lawn two or three times. Then broadcast the seed, and lightly go over the lawn again with the dethatcher.
---Improved turf-type tall fescue varieties include: Jaguar 3, HoundogV, Guardian, Renegade, Rembrandt, Southern Choice, Falcon II, Crossfire II, Apache II, Genesis, Lancer, Marksman, Rebel Jr., Pyramid, Pixie, Eldorado, etc.
---It is very important to regularly water the newly seeded lawn to keep the surface wet. If you cannot water and the weather remains dry, you will not have much success. If you can water 2 or 3 times a day, then you should have green turf beginning to show in about 10 days to two weeks.
---You can apply the first Nitrogen fertilization prior to seeding but it is often better to wait until after germination. If nitrogen is applied at the time of seeding, it may force growth of weeds that compete with the young seedlings of fescue.
Fertilizing immediately after germination gives the desirable grass an advantage.
Mention or display of a trademark, proprietary product, or firm in text or figures does not constitute an endorsement and does not imply approval to the exclusion of other suitable products or firms.
NOTE: Applications are being accepted for the 2010 Master Gardener Volunteer Program until August 1, 2010. Contact the Hardin County Extension Office for more information at 270.765.4121.
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