Assessment of hybrid corn genotypes in the suppression of turcicum leaf blight disease progression in corn under preventive-based protection

Turcicum leaf blight (TLB) is one of the important diseases in corn (Zea mays L.) plants in Indonesia and causes yield losses about 27% to 90%. One of the controls to suppress TLB is using resistant cultivars. This study aims to evaluate the resistance of hybrid corn genotypes to TLB and determine its effect on the epidemic components of the disease. There are four hybrid corn genotypes HCG11, HCG12, HCG13, and HCG14 that were tested with comparison cultivars used are P36, PAC339, NK8103, BISI18, and Anoman. Observation of TLB severity was carried out when plants were 60, 70, 80, and 90 d after plant. The study was prepared using a randomized group design consisting of nine treatments and repeated three times. The observational data were statistically analyzed and continued with least significant different (LSD) test. Analysis of disease progression models in the field was carried out based on goodness of fit tests, area under disease progress curve (AUDPC) and path analysis. The results showed that only the HCG11 genotype showed a somewhat resistant reaction to TLB disease with disease severity of 33.94%, significantly lower than the comparison cvs. PAC339, BISI18, and Anoman in the 5% LSD test. The epidemic component of the disease also showed that the HCG11 genotype had the lowest AUDPC value and infection rate with the highest protection index against TLB disease. Path analysis showed that relative humidity, temperature, precipitation, and wind speed had a significant effect on the progression of TLB disease. Key words: Disease epidemic, disease severity, Exserohilum turcicum, infection rate.