Characterization of dollar spot resistance in seashore paspalum
Steketee, Clinton James
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Turfgrass breeders seek to develop seashore paspalum (Paspalum vaginatum Swartz) cultivars that exhibit resistance to dollar spot disease, caused by Sclerotinia homoeocarpa F.T. Bennett. Three related studies were conducted to improve phenotyping efficiency and to identify new sources of resistance. A field study found no paspalum genotype by dollar spot isolate interaction indicating host plant resistance genes are not isolate specific. Therefore, breeders can use a single virulent isolate to screen for resistance. A detached leaf assay was adapted aiming to find a faster phenotyping technique than traditional field inoculation. The detached leaf assay did show some potential as an efficient phenotyping method, but results did not correlate with field results. In another study, ninety P. vaginatum accessions were screened for their resistance to dollar spot. No lines tested expressed complete resistance and accessions ranged from moderately resistant to very susceptible. No discrete resistance classes were observed, indicating resistance is likely a quantitatively inherited trait. Several seashore paspalum accessions in the collection show promise of improving host plant resistance if used in crosses with elite germplasm.