A Rapid, Reliable Bioassay for Pathogenicity of Colletotrichum magna on Cucurbits and Its Use in Screening for Nonpathogenic Mutants

A rapid, reliable bioassay for large-scale screening of pathogenicity of Colletotrichum magna, a causal agent of anthracnose in cucurbits, was developed. This method involved exposing whole seedlings and cuttings (plants with excised root systems) to conidial suspensions in scintillation vials. The results corresponded well to disease responses observed by the standard leaf inoculation procedures. This continuous dip method allowed for a rapid disease response in cuttings; mortality occurred within 48-72 hr after inoculation (.)