Evaluation of Tropical Maize Germ Plasm for Resistance to Kernel Colonization by Fusarium moniliforme. R. N. Holley, Research Associate, Department of Crop Science, North Carolina State University, Raleigh 27695-7620. P. B. Hamilton, and M. M. Goodman, Professor, Department of Poultry Science, and Professor, Department of Crop Science, North Carolina State University, Raleigh 27695-7620. Plant Dis. 73:578-580. Accepted for publication 14 January 1989. Copyright 1989 The American Phytopathological Society. DOI: 10.1094/PD-73-0578.

A wide range of maize (Zea mays) hybrids were evaluated for resistance to kernel colonization by Fusarium moniliforme. Thirty-four tropical inbreds were topcrossed to two corn belt testers and were combined with eight commercial hybrids to form two tests. The hybrids were evaluated at two locations in North Carolina during the summer of 1985. Grain samples were collected during combine harvesting and were dried to <12% grain moisture. Samples were ground and used to form extracts that were placed on a selective medium to determine the number of colony-forming units of F. moniliforme per gram of grain. Significant differences were found among hybrids for resistance to colonization by F. moniliforme. B73 × Mo17 had the highest mean value for colonization in the study. With the exception of Pioneer Brand 3369A and Pioneer Brand 3055, the commercial hybrids appeared to be more susceptible to pathogen development than the topcross hybrids as a group. The high degree of susceptibility of B73 × Mo17 indicates that the extensive use of hybrids with closely related pedigrees may be an important factor in the increasing incidence of grain contamination by F. moniliforme observed over the past 10 yr. The results of this study indicate that tropical germ plasm may be a source of resistance to this pathogen. However, the measurement error was large and indicates the need for further research into the factors affecting infection and colonization.