During summer 2015, we conducted a trial at the Lake Wheeler Turfgrass Research Farm in Raleigh, N.C. The study took place on a native soil (clay loam) ’Crenshaw’ creeping bentgrass fairway/tee area maintained at 0.375”. In previous work conducted in cooperation with Dr. Damon Smith, we determined that relative humidity above 70% for five consecutive days with a minimum air temperature above 57̊ºF is conducive for dollar spot development. In Raleigh, this typically occurs in April, May, June, September, and October.
We made our first application on April 30th and all treatments were re-applied at 14-day intervals until June 23. During the application period, relative humidity was consistently above 70% and dollar spot pressure was very high. The study was not inoculated. After June 23, relative humidity dropped below 70% until late August. Dollar spot was rated as the percent area of the plot affected and we used 3 ft. x 6 ft. plots (18 ft2).
Fame +T fungicide performed exceptionally well in our trial this year. We did not see statistical differences among rates when we examined the area under the disease progress curve values, which is a measure of disease over time. However, it is important to note that numerically we observed a rate response.
It is also interesting that Fame SC applied on a 14-day interval suppressed dollar spot when compared to the non-treated control. Although almost all of the treatments in this study suppressed dollar spot when compared to the control, only the combination products (Fame +T, Strobe T, Headway and Enclave) limited disease development to less than 0.5 %. This is not unusual and combination products are exceptional when disease pressure is high. Fame +T is an excellent option for dollar spot management even under intense dollar spot pressure.
Jim Kerns, Ph.D., is Assistant Professor and Extension Specialist for the Department of Plant Pathology at N.C. State University. He focuses on etiology, epidemiology and management of diseases of both warm- and cool-season grasses. His research program concentrates on understanding the biology of ultradwarf bermudagrass diseases, Pythium root rot of creeping bentgrass, plant parasitic nematodes in turf and diseases of creeping bentgrass. His program also houses the Turfgrass Diagnostic Lab. He holds a bachelor of science degree from NC State University, a master’s degree from Texas A&M University and a Ph.D. in Plant Pathology from NC State University.