Cultural practices are also a management option , Isakeit says, but their beneficial effects may be limited. Key practices include using the optimal amount of nitrogen fertilizer, crop rotation and tillage.

“The fungus that produces aflatoxin doesn’t grow on crops such as wheat or sorghum, so rotation could be helpful. Also, since the fungus produces spores on cob residue and only spores from surface residue can get to the corn ear, tilling residue into soil may be helpful.”

Biocontrol agents are relatively new tools for aflatoxin management. Two primary products, Afla-Guard and AF-36, are Aspergillus flavus strains that do not produce aflatoxin but, if applied in a timely manner and under proper growing conditions, will produce vast numbers of spores that out-compete the native toxic strains for limited space in the corn kernels.

“Both need moisture, either moist soil or dew, to activate and produce spores,” Isakeit says. The wind picks up spores and carries them to the corn ear. The fungus, which is applied on barley or wheat seed, takes two to three days to sporulate. The grain carrier turns fuzzy green with spores.