CHARACTERIZATION OF THE CHLOROTIC LESION RESPONSE BY MAIZE TO CERCOSPORA-ZEAE-MAYDIS

Previous research indicated that variation in symptom response to Cerc ospora zeae-maydis is associated with maize genotype. An association b etween lesion type at a specific time and overall symptom response has not been described. Inbreds and hybrids grown at several locations du ring 1989-1992 were artificially inoculated with C. zeae-maydis. Genot ypes were evaluated for lesion type responses and percent area affecte d on ear leaves. These evaluations and determinations of secondary spo rulation were performed in 1991 and 1992. Lesion size reduction, delay in disease progress, and inhibition of sporulation were associated wi th chlorotic lesions on resistant inbreds NC250A, NC288, and NC262A. P a875 had fleck lesions that developed into necrotic, susceptible lesio ns by the end of the season, although lesions were few in number and r estricted in size. Hybrids developed by crossing chlorotic lesion inbr eds with nonchlorotic lesion inbred B73 displayed the chlorotic lesion response, indicating the response may be controlled by dominant allel ic interaction.