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Ecology and Epidemiology

Survival of Aspergillus flavus Sclerotia and Conidia Buried in Soil in Illinois or Georgia. D. T. Wicklow, Mycotoxin Research Unit, National Center for Agricultural Utilization Research, U.S. Department of Agriculture, Agricultural Research Service, 1815 North University Street, Peoria, IL 61604; D. M. Wilson(2), and T. C. Nelsen(3). (2)Department of Plant Pathology, University of Georgia, Coastal Plains Research Station, Tifton 31793; (3)Biometrical Services, Midwest Area, U.S. Department of Agriculture, Agricultural Research Service, 1815 North University Street, Peoria, IL 61604. Phytopathology 83:1141-1147. Accepted for publication 21 July 1993. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1993. DOI: 10.1094/Phyto-83-1141.

We examined the survival of sclerotia and conidia produced by Aspergillus flavus var. flavus and A. flavus var. parasiticus that were buried at a depth of 1012 cm for up to 36 mo (October 1986 to October 1989) in sandy field soils near Kilbourne, Illinois, or Tifton, Georgia. Substantial losses of conidial inoculum were recorded after the first year of burial in Georgia and after the second year of burial in Illinois. Conidia of A. f. parasiticus survived for longer periods in soil than did conidia of A. f. flavus. Most sclerotia from eight A. flavus strains were viable at the conclusion of the experiment (Illinois, 7799% viability; Georgia, 68100% viability), as measured by colony growth of A. flavus on potato dextrose agar. None of these sclerotia, however, germinated sporogenically on sand in moist chambers. Production of large numbers of fungal propagules in the soil suggested that some of the sclerotia had previously germinated sporogenically. The number of A. flavus propagules generated from buried sclerotia varied according to strain and location; numbers were maximum after the first growing season. Fungal colonization of A. flavus sclerotia buried in Georgia was dominated by Paecilomyces lilacinus; in Illinois the sclerotia were colonized most frequently by P. lilacinus and Periconia macrospinosa.

Additional keywords: aflatoxin, Bacillus megaterium, mycoparasitism, population dynamics.