The Effects of Nitrogen and Methiozolin on Annual Bluegrass Control and Creeping Bentgrass Recovery on Golf Greens.

Annual bluegrass (Poa annua L.) is considered the most problematic weed on golf greens because of its fecund characteristic, low heat and disease tolerance in the summer, abundant seedhead production, low winter hardiness and light green color. Methiozolin is a newly developed herbicide for annual bluegrass control on golf turf, which has shown its effectiveness and safety on multiple grass species. Nitrogen, as one of the essential elements of plants, plays an important role in the lateral growth/recovery, chlorophyll formation and putting surface quality. Two experiments are being conducted on the Ohio State University Golf Club practice green and one at the Ohio Turfgrass Foundation Research and Education Facility. The first project is a split-plot design with the main plot of methiozolin and two subplot factors of four different nitrogen rates and three fertilizer frequencies to find out the coupling effect of these three factors on creeping bentgrass (Agrostis stolonifera) recovery and annual bluegrass suppression/control in the spring with fall only methiozolin treatments and fall/spring methiozolin treatments. The second project involves three methiozolin treatment rates and four nitrogen rates to determine the best combination of spring methiozolin program and spring fertilization program that shows best control over annual bluegrass while benefiting creeping bentgrass recovery and safety. The third project on the OTF Research and Education Facility is to study the effects of five different nitrogen rates on the lateral growth/recovery and quality of creeping bentgrass with/without methiozolin treatments. Digital Image Analysis (DIA) is used as a new approach for turfgrass surface quality evaluation.