VIEW ARTICLE

Relation of Aspergillus flavus Colony Growth on Three Selective Media to Recovery from Naturally Infested Soil. Gary J. Griffin, Department of Plant Pathology and Physiology, Virginia Polytechnic Institute and State University, Blacksburg, 24061; Robert H. Ford(2), and Kenneth H. Garren(3). (2)Department of Plant Pathology and Physiology, Virginia Polytechnic Institute and State University, Blacksburg, 24061; and (3)Agricultural Research Service, U.S. Department of Agriculture, Tidewater Research and Continuing Education Center, Holland Station, Suffolk, Virginia 23437. Phytopathology 65:704-707. Accepted for publication 31 January 1975. DOI: 10.1094/Phyto-65-704.

Three selective media, inhibiting the colony growth of Aspergillus flavus isolates either slightly, moderately, or severely in pure culture, were evaluated for isolating low populations of A. flavus from naturally infested soil. Recovery of A. flavus by the dilution-plate technique was approximately the same on slightly inhibitory 3% NaCl-Botran-amended medium, and on moderately inhibitory 3% NaCl-rose bengal-amended medium. A. flavus colonies on dilution plates were typically larger on 3% NaCl-Botran medium. Recovery of A. flavus from naturally infested soil on severely inhibitory 10% NaCl-rose bengal-amended medium was similar to that on 3% NaCl-rose bengal medium, but A. flavus colonies were larger on dilution plates of the former due to less crowding from undesired fungi. In contrast, recovery of A. flavus from nonsterile soil artificially infested with conidia was greater on media less inhibitory to A. flavus growth in pure culture. Conidia were one of the principal propagules of A. flavus in naturally infested soil. Conidial germination by A. flavus in pure culture was 88-100% within 24 hours on all three media. Severe growth inhibition of the desired fungus on a selective medium may not lead to reduced recovery, on a relative basis, from naturally infested soil.