Effect of Genes with Slow-Rusting Characteristics on Southern Corn Rust in Maize. Gene E. Scott, Supervisory Research Agronomist, Agricultural Research Service, U.S. Department of Agriculture, and Professor, Department of Agronomy, Mississippi State University, Mississippi State 39762. Natale Zummo, Research Plant Pathologist, Agricultural Research Service, U.S. Department of Agriculture, and Professor, Department of Plant Pathology and Weed Science, Mississippi State University, Mississippi State 39762. Plant Dis. 73:114-116. Accepted for publication 14 August 1988. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1989. DOI: 10.1094/PD-73-0114.

Eight experimental maize (Zea mays) inbreds previously identified as having slow-rusting resistance to southern corn rust (Puccinia polysora) on the basis of reduced pustule number, smaller pustules, and delayed pustule rupture were crossed with a susceptible inbred, CI21. Crosses between some of the slow-rusting inbreds were also made. These two groups of crosses were compared with each other and with resistant and susceptible hybrids under field inoculations. Compared with susceptible hybrids, crosses among inbreds with slow-rusting characteristics had fewer and smaller pustules that ruptured later. On resistant genotypes, the direct effect of fewer and smaller pustules was that smaller areas of leaf were destroyed and the indirect effect was that fewer urediniospores were produced and their dispersion was delayed because pustule rupture was delayed.

Keyword(s): disease development, disease resistance.