Effects of Turf Covers and Plant Growth Regulators on Spring Growth and Quality of Kentucky Bluegrass.

Kentucky bluegrass (Poa pratensis L.) is one of the slowest species to resume active growth in the spring. Previous research has shown that short term (14-28 days) covering events will promote spring greening and growth, but the covered areas usually have a marked decline in turf quality later in the spring season. The purpose of this study was to determine if the use of trinexapac ethyl (TE) can regulate the spring surge in growth caused by short term covering and eliminate the later decline. Four cover sources were used: a white polypropylene product from Xton Inc.; a white nonwoven geotextile from Surline Turf; an experimental reflective material known as Aluminet from Xton, Inc., and an uncovered control as whole plot effects. In 2007, TE was applied at a rate of 0.21 L/ha as a sub-plot treatment in 0.9 m strips across the whole plots immediately prior to covering, 10 days after covering, and no TE treatment. Across all TE treatments, all covers provided a visibly improved color and quality response three weeks after initial covering. The best initial color response was observed with Xton’s white polypropylene weave, followed by the white geotextile. The uncovered check and Aluminet treatments had the highest color and quality responses by the end of the study. Clipping yields were significantly enhanced by the two white covers at three weeks after covering and there was no clipping yield response between covers at trial’s end. The control did have higher clipping production than the two TE treatments at the conclusion of the study. Further investigation into the effects of cover type, PGR type and application timing were conducted in spring 2008. Effects on tiller density and carbohydrates from the 2008 trial will be presented, along with recommendations for field managers.