Biological Control to Reduce Inoculum of the Tan Spot PathogenPyrenophora tritici-repentisin Surface-borne Residues of Wheat Fields

Abstract

Field plots of conservation-tillage wheat straw naturally infested with Pyrenophara tritici-repentis were treated with bran-based inoculum of three potential biocontrol fungi, and reduction in the number of residue-borne pseudothecia (primary inoculum of the pathogen) was determined. Limonomyces roseipellis significantly reduced residue-borne primary inoculum of P. tritici-repentis in 3 of 4 yr of experiments; and unidentified agonomycete was effective in two of three experiments, but Laetisaria arvalis was ineffective. Although L. roseipellis reduced inoculum by 60-80%, greater reductions would be necessary for acceptable control of this disease. Retention of dry bran-based inoculum on straw was enhanced by the use of alginate, but further improvements in formulation and application methods are required for effective biocontrol of pathogens in surface-borne crop residues