BIOLOGICAL-CONTROL TO REDUCE INOCULUM OF THE TAN SPOT PATHOGEN PYRENOPHORA-TRITICI-REPENTIS IN SURFACE-BORNE RESIDUES OF WHEAT FIELDS

Field plots of conservation-tillage wheat straw naturally infested with Pyrenophora 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, an 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.