COURSE CARE
Overseeding Transition Time May 11, 2014 By John H. Foy

With increasing temperatures and humidity, cool-season overseeding grasses are starting to rapidly decline. A proactive management program has always been the best strategy for avoiding the overseeding transition blues.

During the last decade there has been a tremendous reduction in both the number of courses and the amount of area that is overseeded each winter in Florida. However, overseeding is still considered a necessary practice at courses in central and North Florida with older Tifdwarf bermudagrass putting greens. Furthermore, tees and fairways are often overseeded at resort courses to ensure playing conditions and aesthetic characteristics meet golfer expectations during the busy winter golf season. With winter now winding down and warm temperatures returning, the transition back to the base bermudagrass is beginning to occur.

The establishment of an overseeding cover in the fall exerts additional stress and competition on the base bermudagrass. Therefore, there is always the potential for areas of weak, thin turf to be exposed as cool-season overseeding grasses, such as Poa trivialis and ryegrass, naturally begin to die with the persistence of hot, humid conditions. Employing a proactive transition-management program that gradually thins out the overseeding cover at the same rate that the base bermudagrass is able to fill in and maintain coverage is the best strategy for minimizing, but not totally eliminating, a pronounced deterioration in the condition and quality of overseeded areas. Please see the USGA Green Section Webcast,Winter Overseeding Transition Management, which reviews the basic components of a proactive transition-management program.

With a proactive transition-management program and some cooperation from the weather it is possible to complete the transition to bermudagrass without golfers being aware it is underway. However, the weather is a controlling factor in all agricultural endeavors including golf course management. Cool, wet conditions during the spring hinder the resumption of sustained, active bermudagrass growth and also favor the persistence of cool-season grasses used to overseed bermudagrass in the fall. If a moderate to high percentage of the overseeding cover is still present in late May to early June, application of a sulfonylurea herbicide may be necessary to complete the transition process. Complete removal of the overseeding material by early summer is very important to provide the base bermudagrass with at least 100 growing days without competition. This is needed to ensure that the base bermudagrass is able to fully recover from the negative impacts of overseeding. If the bermudagrass is not able to fully recover from overseeding damage, the potential for problems and “transition blues” the following year are further increased.

Source: John Foy (jfoy@usga.org)

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