Evaluation of Talaromyces flavus as a Biological Control Agent Against Verticillium dahliae in Potato. David S. Spink, Former Graduate Student, Department of Plant Pathology, The Ohio State University, Ohio Agricultural Research and Development Center, Wooster 44691. Randall C. Rowe, Professor, Department of Plant Pathology, The Ohio State University, Ohio Agricultural Research and Development Center, Wooster 44691. Plant Dis. 73:230-236. Accepted for publication 31 October 1988. Copyright 1989 The American Phytopathological Society. DOI: 10.1094/PD-73-0230.

Talaromyces flavus was evaluated as a potential biological control agent of Verticillium dahliae on potato in field microplot studies by amending soil with various levels of microsclerotial inoculum of V. dahliae and various rates of pyrophyllite- (Pyrax) base pellets containing ascospores of T. flavus. Verticillium-free potato seed pieces were planted in test soils and the plants that developed were evaluated over time. Disease progress and yields were not consistently affected by applied rates of T. flavus pellet inoculum at any level of V. dahliae. Populations of V. dahliae recovered from soil or plant roots at harvest were also unaffected by rates of pellet inoculum of T. flavus. Recovery of T. flavus from rhizosphere soil clinging to potato root sections at harvest in both years of the study never exceeded 6.8% of the sections. Wheat bran-base pellet inoculum of T. flavus increased recovery of T. flavus sixfold to 10-fold from rhizosphere soil and 1,000-fold from nonrhizosphere soil compared with the Pyrax-base pellet inoculum. Despite this increase, there was still no significant effect on disease development, tuber yield, or percent recovery of V. dahliae from rhizosphere or nonrhizosphere soil at harvest.