Soils suppressive to Gaeumannomyces graminis var. tritici: Induction by other fungi

Rhizosphere soils were obtained from wheat plants growing in fumigated soil inoculated with one of the pathogens, Rhizoctonia solani, Gibberella zeae, Fusarium culmorum, Cochliobolus sativus and Pythium irregulare or one of the non-pathogenic fungi, Gaeumannomyces graminis var. graminis (Ggg) or a Phialophora-like fungus ( Plf). Using a pot bioassay, these soils were tested for suppression of Gaeumanomyces graminis var. tritici (Ggt) and the fungus involved in the initial induction. G. zeae was the only fungus that induced suppression to Ggt and to itself. Ggg but not Plf induced suppression to Ggt although both fungi induced suppression to themselves. Fungi capable of inducing suppression of take-all have two characteristics in common, they induce suppression of themselves and their saprophytic survival is restricted to organic matter.