A role for managanese in the resistance of wheat plants to take-all

Summary The hypothesis that wheat plants deficient in managenese are predisposed to infection byGaeumannomyces graminis is outlined, and a test of the hypothesis in a soil system is reported. The results supported the hypothesis: wheat plants growing in managanese-deficient soil, although not showing foliar symptoms, were markedly more susceptible to infection; plant analysis confirmed the nutrient status of the plants. A review of the literature on take-all in wheat coupled with the results of our experiments suggests a reinterpretation of the etiology of this disease, since those edaphic factors which promote infection by this organism are those which also render managese unavailable to the host. Managenese nutrition is proposed as a common factor in many of the environmental conditions which influence the host-pathogen balance.