RAPID IDENTIFICATION OF XANTHOMONAS-FRAGARIAE IN INFECTED STRAWBERRY LEAVES BY ENZYME-LINKED-IMMUNOSORBENT-ASSAY

An indirect enzyme-linked immunosorbent assay using the F(ab')2 fragme nt as a trapping antibody for Xanthomonas fragariae was developed. The pathogen was detected in extracts of single 4-mm leaf disks containin g a 4- to 5-day-old lesion obtained by artificial inoculation or lesio ns in field collections from plants showing symptoms of angular leaf s pot disease. Our antiserum reacted positively with 34 strains of X. fr agariae but not with 16 of 17 pathovars of X. campestris and strains o f Agrobacterium spp., Erwinia amylovora, Pseudomonas spp., Rhodococcus fascians, and nonpathogenic bacteria isolated from strawberry plants.