Survival and spread of Phytophthora capsici on Long Island, New York

Phytophthora capsici is an oomycete soil-borne plant pathogen that causes root, fruit and foliar disease on a variety of vegetables. The epidemiology and population structure varies depending on the region surveyed and our objective was to investigate survival and spread on farms on Long Island, New York using single nucleotide polymorphism (SNP) markers. A total of 373 P. capsici isolates were collected from pumpkin, pepper, watermelon and snap bean on 15 farms. Both mating type were recovered from most locations. Genotypic analysis was conducted using 14 SNP loci located primarily within genes. A total of 128 unique multi-locus genotypes were identified. Of these, 54 appear to be clonal lineages ranging in size from 2 to 26 members. Most clonal lineages were recovered during the same year. Our results indicate that both sexual and clonal reproduction play important roles in the epidemiology of P. capsici on Long Island, NY, USA. The implications for managing the disease are discussed.