4/12/2013

Overseeding sports fields has become a very common practice in the transition zone.  Perennial Ryegrass is the most common overseeding grass, and provides a vigorous, beautiful playing surface throughout the winter and spring.  Seed companies have bred cultivars that are increasingly resistant to drought, disease, and heat, because they are perennial species after all.  This presents a special set of challenges to the southern sports turf manager who plans to grow ryegrass as an annual crop, as these super-cultivars of ryegrass are very adept at competing with bermudagrass for light, water, and nutrients.  There are, however, options to smoothly transition from overseeded to Bermuda turf which we’ll call chemical or non-chemical transition.

Non-Chemical Transition

In non-chemical transition the sports turf manager will manipulate cultural practices in an attempt to allow the Bermuda to outcompete the rye.  Lower mowing heights, aggressive verti-cutting and aerification, high fertility, and reduced irrigation are used to try and give the bermudagrass the upper hand in the competition for light, water, and nutrients.  The downsides to this method are: a decrease in turf quality during the periods of aggressive cultivation and the likelihood that you’ll selectively control only the weakest ryegrass plants leaving the sports turf manager with only the strongest plants that will be even more difficult to control in the coming years.

Chemical Transition

Chemical transition of ryegrass is becoming the industry standard at all levels excluding professional baseball.  Chemical transition uses a selective herbicide to eliminate the ryegrass and allow bermudagrass access to all the light, water, and nutrients it needs.  The downsides to this method are: the plant growth regulation characteristics of some of the chemicals used on bermudagrass and the loss of turf quality in the weeks following treatment as the ryegrass dies at a rate faster than the bermudagrass greens up.

Recently the turf team at Clemson University applied principles from both chemical and non-chemical transition to try and eliminate the, temporary, loss of turf quality that often occurs with each.  Their work is published here (PDF).   They had very good results with lower mowing heights, increased fertility, and use of SU herbicides.

Overseeding of sports turf has become a necessary evil, but there have never been better options for transitioning back to bermudagrass.  Using the above techniques should minimize the pain and heartache associated with this practice.

Click here for more information: Optimizing Spring Transition of Perennial Ryegrass (PDF - Clemson University).