Population patterns of Aspergillus flavus group and A. niger group in field soils

The horizontal distribution of soil-borne fungi in field soils is an important component of fungal ecology. Aspergillus flavus group and its antagonist, the A. niger group, had moderate and moderate to high degrees of aggregation (patchiness), respectively, in two peanut fields with a history of aflatoxin contamination: Lloydʹs index of patchiness values ranged from 2.32 to 6.55, where 1.0 is a random pattern. For the A. niger group, there was evidence that quadrats in close proximity had similar population densities. Clump size, rarely reported for soil-borne fungi, was found to be 13–52 m2 for A. niger group in one field. Mean population densities of A. flavus group in both fields were higher than found previously in most Virginia peanut fields and, along with moderate aggregation, may be related, in part, to the occurrence of aflatoxin in these fields.