Sources of resistance to corn leaf blight

Abstract

Different types of resistance to Helminthosporium turcicum were investigated. Maize inbreds with monogenic, polygenic, incomplete dominant gene for monogenic resistance (HTN). Mayorbella (a resistant breeding line) as well as inbreds susceptible “northern corn leaf blight” (N.C.L.B.) were compared under field conditions and controlled environmental conditions after inoculation with H. turcicum. These studies included a comparison between lesion sizes, number of lesions per leaf, time of lesion development and incidence of conidiation. The host reaction to the pathogen in the field and in the controlled environment room was not the same. Polygenic resistance was effective in the field with adult plants, but not in the seedling stage. Similarly, the resistance breeding line Mayorbella was also susceptible in the seedling stage. Monogenic type of reaction was resistant in both environments. There are other types of resistance; hypersensitive type of reaction, HT₁ and the resistance present in the breeding line Mayorbella which also can provide an effective resistance mechanism being useful disease control.