Thatch – The Living Dead!

Mark Williams  |  8/7/2015 11:50:56 PM

Vertical Lawn Mower

Lawn Profile

Thatch – The Living Dead!

All lawns have a layer thatch, which is not always harmful to the grass. What is thatch? Thatch is a layer of living and dead grass plant parts and clippings located between the soil surface and the green growing grass. Although thatch is normally a problem in zoysia grass, it can also develop serious problems in St. Augustine, centipede and Bermuda grass lawns when not controlled. A thin layer of thatch is beneficial because it reduces water loss from the soil during drought, helps provide a cushion and reduces the stress of foot traffic. However, thatch may accumulate faster than it decomposes when lawns are over fertilized, overwatered, and mowed too infrequently or mowed too high.

Excessive thatch creates many problems. The turf begins growing in the thatch instead of in the soil. The sponginess of the thatch is evident as you walk across the lawn, also the mower tends to sink into the thatch and scalp off the grass. Insects and disease thrive in the thatch environment further weakening the turf plants. Water and fertilizer cannot penetrate through the thatch layer. Excessive thatch may increase winter damage and drought susceptibility.

A lawn that needs dethatching is evident when the thatch layer is greater than half to three quarters of an inch. Remove thatch by using a specially designed power rakes, vertical lawn mowers and or core aerifiers. This equipment is available from most of the local rental stores. (See photos)

By lowering the fertility rate, watering properly and by following correct mowing practices can decrease and control the rate at which thatch will accumulate. The application of light topdressing of soil mixed with course sand 1/4-inch thick can reduce thatch problems. At this rate, you will need 3/4 cubic yard of sandy soil to top-dress 1,000 square feet.

Mark Williams, Assistant Extension Agent (ANR) for East Baton Rouge Parish, compiled this article. For more information concerning this article or related topics, please contact the EBR Parish Extension Office at 225-389-3055.

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