The Trouble with Thatch

By Todd Lowe, Agronomist
September 15, 2008

Thatch is defined as the living and non-living material located between green turfgrass leaves and the underlying soil. Bermudagrass turf in the Florida Region accumulates a large amount of organic matter, and it is best to use the terms "thatch" and organic matter or "mat". In this case, thatch is the layer of turfgrass stems located just below the green leaf canopy and mat is the dark organic material located under thatch. Some thatch and mat is necessary for surface resiliency and nutrient retention, but excessive thatch can cause major issues with playability and turf health.

The issue of thatch and organic matter is discussed often during summer TAS visits in the Florida Region as golfers complain about cultivation programs like core aeration, vertical mowing, and sand topdressing. In fact, a common phrase at many golf courses we visit is, " Our superintendent just loves to poke holes in the turf. It seems like the holes are just filling in, when he/she is right back on them poking more holes! " Let's face it, no golfer likes to play on bumpy, sandy putting greens that have just been aerated, and summer cultivation can be quite an annoyance. Unfortunately, aggressive cultivation programs are necessary to maintain premium playing conditions and these practices must take place during periods of optimum turf recovery (i.e. the summer months). This generally equates to some type of cultivation occurring during much of the summer season.

Excessive thatch and organic matter is a primary stress on bermudagrass putting greens. It causes greens to remain saturated in the upper rootzone, reducing oxygen uptake and encouraging root decline. Saturated conditions also can encourage diseases like Pythium as well.

The old saying " Pay me now or pay me later " is certainly true for managing thatch and organic matter. The inconvenience of paying now and tolerating less than ideal playing conditions for several days is often far less painful than enduring diseased, weak putting greens or large scale turf thinning.

Source: Todd Lowe, tlowe@usga.org or 941-828-2625