The effects of mixing barley cultivars on incidence of powdery mildew (Erysighe graminis) and on yield in Northern Ireland

Abstract

SUMMARYSowing mixtures of cereal cultivars has been advocated as a strategy to reduce yield loss resulting from disease in the short term and to delay adaptive changes amongst the races in the pathogen population in the long term. Six spring barley cultivars, Midas, Athos, Sundance, Mazurka, Goldmarker and Golden Promise, and seven selected paired mixtures of these, combined according to the compatibility of their resistance genes, were grown in field experiments during 3 yr. Where natural infection by powdery mildew (Erysiphe graminis) was severe, as in 1980, levels of infection in the mixtures were less than the mean of the components in monoculture. Yields were generally increased by combining cultivars; mixtures of Athos with Midas and with Mazurka gave yields over 8% higher than the mean yields of their components but these apparent synergistic effects could not be associated with reductions in levels of mildew infection.