Effect of Cultural Practices on the Soil Population of Aspergillus flavus and Aspergillus parasiticus1
- J. S. Angle,
- K. A. Dunn and
- G. H. Wagner2
Aflatoxin is a highly toxic compound and potent carcinogen produced by the fungi Aspergillus flavus and Aspergillus parasiticus. Corn infected by these organisms is frequently contaminated with aflatoxin. The infection of corn by A. flavus and A. parasiticus often occurs while the crop is still in the field. Because A. flavus and A. parasiticus are indigenous soil inhabitants, the soil is an important source of inoculum.
This study was undertaken to quantify the population of A. flavus and A. parasiticus in soil and the ability of these organisms to produce aflatoxin. Soils under 11 different cultural systems were examined to determine the effects of the different practices on A. flavus and A. parasiticus.
The maximum number of A. flavus and A. parasiticus propagules was found in soil cropped to a rotation of wheat, red clover, and corn using conventional tillage practices. In this soil, which had also been amended with manure, the count of A. flavus was 68 and that of A. parasiticus was 211 propagules per gram of dry soil. No A. flavus or A. parasiticus isolates were observed in a virgin prairie soil. Of all isolates observed from all cropping systems, 43% were A. flavus while 57% were A. parasiticus. The ability of the different isolates to produce aflatoxin varied significantly. In general, however, A. parasiticus isolates exhibited a greater ability to produce aflatoxin than did A. flavus.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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