Etiology of cereal root rots in California

Abstract

This report … covers an investigation of the cereal root-rot complex in California. From 134 cereal fields (primarily wheat and barley) representing 20 counties, the following rootrotting fungi have been isolated: Primary pathogenic fungi: Helminthos porium sativum P., K. et B. Fusarium roseum f. cerealis (Cke.) emend. Snyd. et Hans. (both Gibberella- and nonperithecium-producing clones) Ophiobolus graminis Sacc. Fnsarium nirale (Fr.) Ces. emend. Snyd. et Hans. (first record in California as a root-rotting parasite) Pathogenic fungi of occasional importance: Pvthium graminicolum Subr. (first record in California) Sclerotium rolfsii Sacc. Rhizoctonia solani Kühn Fungi of secondary importance: Wojnowicia graminis (McAlp.) Sacc. and Sacc. Fusarium monililorme Sheld. emend. Snyd. et Hans. Fusarium roseum Lk. emend. Snyd. et Hans. Gibberella-producing clones of Fusarium roseum f. cerealis are commonly isolated from roots and crowns. Head blight. or kernel scabbing, does not seem to be caused by this fungus in California. Its absence is accounted for by a lack of ascospore inoculum and by inadequate humidity at the time of heading. Fields known to be infested by the primary pathogens are tabulated by counties. Each associated fungus is discussed, together with the symptoms it causes and its importance in the root-rot complex in California.