Gibberella stalk rot (Fusarium graminearum) resistance of maize inbreds and their F1 hybrids and their potential for use in resistance breeding programs

P>Fusarium graminearum Schwabe is one of the predominant fungal species responsible for stalk rot of maize in Canada and many other countries. Adapted sources of resistance to this disease are scarce but recently a few have been identified. To evaluate the usefulness of these sources in a breeding programme to improve stalk rot resistance, a complete diallel cross of five inbreds of varying susceptibility to stalk rot was conducted. Artificial inoculations of stalks were accomplished by injecting a conidial suspension into the first internode above the uppermost aerial root node. Stalk rot ratings, yield and lodging in the parents, crosses and reciprocals were evaluated over two field seasons. There were significant differences between inbred lines and hybrids for stalk rot ratings. Inbreds CM174 and CO325 were highly susceptible, whereas inbreds 73405 and 73353 were classified as resistant and both had good general combining ability. Those inbreds could be used as donors of favourable alleles in breeding programmes for Gibberella stalk rot resistance.