Survival of Gaeumannomyces Graminis Var. Tritici in Artificially Colonized Straw Buried in Naturally Infested Soil

Abstract

A study was made of the survival of G. graminis var. tritiei in artificially colonized straws buried in naturally infested soil. The fungus already present in the naturally infested soil generally survived better than the fungus in the straw. A comparison was made of the survival of two isolates of G. graminis var. tritiei in artificially colonized straws stored in similar soils from the same area, but with different cropping histories. Generally, survival decreased with increasing numbers of consecutive crops; this suggested that some 'factor' reducing saprophytic survival of G. gram in is var. tritiei in artificially colonized straws is induced in soil that is continuously cropped to wheat. It was also shown that the isolates (which had similar levels of virulence) had different survival abilities. This appeared to be related to differences in production of dark hyphae. When either isolate survived, it maintained its original virulence and also maintained its inoculum potential at an approximately constant level after an initial drop during the first 10 weeks of survival.