Few data are available that evaluate the impact of variety mixtures on the Septoria/Stagonospora diseases of cereals. The splash-dispersed nature of the pathogens and the predominance of quantitative variation for host resistance and pathogenicity in the Septoria/Stagonospora diseases may make interactions more complex than for the rusts and mildews, where major gene interactions have been the main object of study. We have found that epidemic progression of septoria tritici blotch can be substantially suppressed in mixtures of a susceptible and a moderately resistant variety, sometimes to below the level of the more resistant variety grown in pure stand. Mycosphaerella graminicola populations sampled from variety mixtures have been found to be reduced in pathogenicity in all mixtures that have been investigated thus far. Disruptive selection may be an important mechanism affecting disease progression and evolution of M. graminicola in variety mixtures. Major genes for resistance have the potential to contribute substantially to the use of variety mixtures for control of Septoria/Stagonospora diseases, both through their epidemiological impacts on disease spread, and through effects of induced resistance between avirulent and virulent genotypes of the pathogen that may occur in variety mixtures.

English

9910|AGRIS 0001

Jose Juan Caballero

CIMMYT Publications Collection