Fusarium/Gibberella Identified in Wisconsin Sweet Corn Fields

September, 1995

Joe Lauer and Craig Grau

Recently Fusarium/Gibberella was observed in sweet corn fields in east-central Wisconsin. This fungus can produce mycotoxins which lead to animal performance problems such as feed refusal, vomiting, and estrogen syndrome. According to Gene Smalley, ".. there is lots of Fusarium around in 1995 ..." Some sweet corn fields had 25% of the ears infected. Sweet corn varieties are more susceptible to Fusarium than dent corn hybrids.

A hot and cold temperature cycle favors the development of the mycotoxins, deoxynivalenol and zearalenone, by the fungus. Unfortunately, presence of Fusarium does not always indicate presence of mycotoxin. Thus, threshold levels are difficult to develop for this fungus. Ruminant animals can handle much higher levels of mycotoxin, while swine will express estrogenic problems with contaminated feed of a few parts per million mycotoxin.

Below are some guidelines for handling corn infested with Fusarium/Gibberella:

1. The safest course of action for by-passed sweet corn fields is to plow the corn under.
2. Positively identify the fungus as Fusarium roseum f. sp. ceralis (sexual stage Gibberella zeae). If positively identified, have the plant material sampled and analyzed for the presence of the mycotoxin and the amount. Keep in mind that mycotoxins can develop quickly even between the time that the sample is taken and the results are sent back.
3. Harvest as soon as the moisture content allows adequate fermentation and ensiling. Proper ensiling will stop growth of the fungus developing on the ear, but will not destroy the mycotoxins. Silage will dilute concentrations of the mycotoxin on the ear with the stover.
4. Another possible course of action is to green-chop and feed immediately. This will dilute concentrations of the mycotoxin on the ear with the stover.
5. Several organic acids - propionic, isobutyric and acetic - can be used to stop fungal growth. These compounds will not destroy the mycotoxin.
6. Begin feeding plant material to heifers and cull cows to determine if there are detrimental effects of the feed. Do not feed to high performing dairy animals until you are sure that there are no feed effects.

A number of commercial labs will test for the presence of mycotoxins. The Wisconsin Department of Agriculture - Animal Health Laboratory will also test samples (please call Wayne Brown or Anita Kore at 608-266-2465).