Response of Seashore Paspalum Genotypes to Two Isolates of Sclerotinia homoeocarpa

Seashore paspalum (Paspalum vaginatum) is a warm-season turfgrass noted for its salt tolerance and is used on golf course fairways and greens. Dollar spot (Sclerotinia homoeocarpa) is an important disease of seashore paspalum, causing distinct silver dollar-sized necrotic patches to form on the turf. Previous research by Flor et al (2013) identified host plant resistance as a potential tool for dollar spot disease management, using a single dollar spot isolate, UF0421. However, another isolate appeared more virulent in follow-up experiments. With the intent of developing stronger selection pressure, disease response to these two characterized S. homoeocarpa isolates was compared in the current study under controlled environmental conditions using nine experimental lines of seashore paspalum, and two commercial cultivars (‘SeaDwarf’ and ‘Sea Isle Supreme’) as controls. The second, putatively more virulent isolate consistently caused more damage to all eleven paspalum genotypes. An isolate × genotype interaction was not observed. Plant genotypes differed significantly in disease response, and all genotypes, but one, were consistent with the previous study. We successfully identified a more virulent strain of dollar spot. Using a more virulent strain will provide stronger selection pressure for development of resistance to dollar spot, allowing for clearer identification of resistant genotypes.