Seashore Paspalum Cultivar Susceptibility to Large Patch and Fungicide Evaluation for Disease Control in South Carolina

Large patch (LP) caused by Rhizoctonia solani AG 2-2 ‘LP ’ is an important disease of seashore paspalum in South Carolina. Two research putting greens were constructed in 2005 at the Pee Dee Research and Education Center, Clemson University, in Florence, SC and at May River Golf Club, Bluffton, SC and planted to cultivars ‘SeaIsle 1’, ‘SeaIsle 2000’, ‘SeaIsle Supreme’, ‘Sea Spray’, ‘SeaDwarf’, ‘Aloha’ and ‘Salam’. A split plot randomized complete block design experiment, with 3 blocks at each location was conducted with cultivars as the whole plots and no fungicide or fungicides as sub-plots. Disease severity (DS) was visually evaluated. Sub-plots were treated with fungicides three times in fall 2005 on 21 day intervals, at low label rates. Epidemics of LP occurred at both locations in fall and winter months. There were no cultivar ´ fungicide interactions at either location. All cultivars were affected by LP and severely damaged in non-fungicide treated plots. The most susceptible cultivars at Bluffton were ‘SeaIsle I’ and at Florence ‘SeaIsle 2000’. ‘SeaIsle Supreme’, ‘Aloha’ and ‘SeaSpray’ were damaged less. Fungicides giving the best control were azoxystrobin at 0.028 g/m² and pyraclostrobin at 0.079 g/m² when compared with untreated control plots. Thiophanate methyl at 0.61 g/m² performed well at Florence but not at Bluffton. No significant differences were found among chlorothalonil at 0.805 g/m², iprodione at 0.228 g/m² and untreated control plots. We conclude that LP is a major disease of seashore paspalum in transition zone climates and will require fungicide treatment for acceptable quality.