We developed one species-specific PCR assays for rapid and accurate detection of the pathogenic fungi Verticillium albo-atrum in diseased plant tissues and soil. Based on differences in internal transcribed spacer （ITS） sequences of Verticillium spp., a pair of species-specific primers, Vaal/Vaa2, was synthesized. After screening 17 isolates of V. alboatrum, 121 isolates from the Ascomycota, B asidiomycota, Deuteromycota, and Oomycota, the Vaal/Vaa2 primers amplified only a single PCR band of approximately 330 bp from V. albo-atrum. The detection sensitivity with primers Vaal/Vaa2 was 10 fg of genomic DNA. Using ITS1/ITS4 as the first-round primers, combined with Vaa1/Vaa2, the nested PCR procedures were developed, and the detection sensitivity increased 1 000-fold to 10 ag. The detection sensitivity for the soil pathogens was 100-conidiag^-1 soil. The PCR-based methods developed here could simplify both plant disease diagnosis and pathogen monitoring as well as guide plant disease management.
