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United States Department of Agriculture

Agricultural Research Service

Title: Effect of Soil Density of Aspergillus Species on Invasion of Peanut Seeds

Author
item Horn, Bruce

Submitted to: Mycological Society of America
Publication Type: Proceedings
Publication Acceptance Date: March 31, 2003
Publication Date: June 22, 2004
Citation: Horn, B.W. 2004. Effect of soil density of aspergillus species on invasion of peanut seeds. Mycological Society of America. Inoculum. p. 25-26.

Interpretive Summary: Not required.

Technical Abstract: Soil is the source of primary inoculum for Aspergillus flavus and A. parasiticus, fungi that produce the highly carcinogenic aflatoxins in agricultural commodities. Aflatoxigenic fungi commonly invade peanut seeds during maturation and the highest concentrations of aflatoxins are found in insect-damaged seeds. A laboratory assay was developed in which sterile, viable peanut seeds were wounded and inoculated with different soils (n = 20) from cultivated and fallow fields and from forested land. Percent seed infection linearly regressed on soil population density was significant (P < 0.05) for all species in Aspergillus section Flavi: A. flavus L strain (R2 = 0.89), A. flavus S strain (0.82), A. parasiticus (0.36), A. tamarii (0.77), A. caelatus (0.37) and A. alliaceus (0.87). Species from other sections in the genus, A. niger (0.76) and A. terreus (0.88), also showed significant linear regressions. Nearly all seeds became infected with A. flavus L strain at >300 CFU/g soil. The density of aflatoxigenic fungi in soil may be a factor in determining the extent of aflatoxin contamination in peanuts.

Last Modified: 8/30/2014
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