By Paul Vincelli, University of Kentucky

Corn Pre-harvest contamination of corn with fumonisins is a possibility in some lots of this year’s Kentucky corn crop.

Fumonisins are a family of mycotoxins which have the potential to cause lethal diseases of horses and swine (the diseases are equine luekoencephalomalacia and porcine pulmonary edema, respectively).

Pre-harvest contamination of corn by fumonisins is most often associated with drought stress at the silking stage, which many fields experienced in 2005. In fields in both Western Kentucky and the Bluegrass region, I recently have seen symptoms of Fusarium kernel rot, the rot typically associated with fumonisins. Kernels often exhibit salmon-pink to reddish discoloration on uninjured kernel caps. Symptoms of Fusarium kernel rot usually occur scattered throughout the ear on individual kernels or groups of kernels. The rot can also be associated with insect injury.

Once symptoms develop, the pathogen sometimes continues to spread on the ear and form a heavy cottony mycelial growth that can consume the entire ear, especially if there is moisture under the shuck. Maturing ears which were pointing upright during the heavy rains associated with Tropical Storm Katrina as it passed through Kentucky may have absorbed moisture, especially if there was some opening of the husk due to birds or other animals. This combination of mid-season drought and heavy rains during maturation could spell trouble for some fields.

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