INFECTION CYCLE COMPONENTS AND DISEASE PROGRESS OF GRAY LEAF-SPOT ON FIELD CORN

The epidemiology of gray leaf spot disease (GLS) on field corn (Zea ma ys) was studied following artificial inoculation with the fungus, Cerc ospora zeae-maydis. Studies were based on relative differences in sele cted infection cycle components between a susceptible and a moderately resistant corn hybrid. Area under the disease progress curve, apparen t infection rate, number of lesions, and sporulation capacity were low er and latent period was longer on the moderately resistant hybrid tha n on the susceptible hybrid. Based on comparisons of disease progress curves, infection cycle components, and rainfall patterns, it is postu lated that rainfall and sporulation during early infection cycles have a significant effect on development of GLS. Management strategies aim ed at decreasing levels of inoculum during early infection cycles are suggested as an effective means of reducing the severity of GLS.