The Effects Of Ultraviolet-B Light Radiation On The Development and Growth Of Dollar Spot.

Dollar spot (Sclerotinia homoeocarpa F.T. Bennett) is the most economically important turfgrass disease in the United States. Recent research in vivo and in vitro suggests that ultraviolet-B (UVB) light radiation may be involved in regulating the growth and spread of dollar spot. A field experiment was conducted at the East Tennessee Research and Education Center in Knoxville, TN, during May and June of 2013. Plots of creeping bentgrass (Agrostis stolonifera L.) were maintained at 3 mm and were screened with polyvinyl chloride (PVC) frames covered with plastic filters designed to either transmit all solar wavelengths or to mostly exclude the UVB (315-280 nm) spectrum. The UVB transmitting control treatment (UVB+) was covered with polystyrene sheets (1.3 mm thickness) while the UVB excluded treatment (UVB-) had Mylar film (125 µm) superimposed on the polystyrene sheets. The Mylar film shields all solar radiation below 310 nm. These filters were fitted 40 cm above the turfgrass canopy and were oriented in an east-west direction. The number of dollar spot infection centers (visual count) and percent disease severity (digital image analysis) were evaluated every 1-5 days. The UVB- treatment resulted in a greater number of dollar spot infection centers per plot compared to the UVB+ treatment on 7 of the 14 rating dates. Increased disease severity was observed for UVB- treatments on 6 of the 14 rating dates. Determining the susceptibility that Sclerotinia homoeocarpa has to UV radiation may lead to improved forecasting models and novel treatments to reduce dollar spot incidence.