Some observations on microbial populations and nitrogen in soils infested with the take-all fungus

Some possible causes of “take-all decline”, the decrease in the severity of attack by Gaeumannomyces graminis on cereals after several years' consecutive culture, are discussed. The possible relationships between the NO₃^?–N:NH₄⁺–N ratio in the rhizosphere, populations of rhizosphere bacteria and the incidence of take-all are considered.