1995 Harvest: Some Concerns

September 21, 1995 2(25):156

Joe Lauer and Graig Grau
Corn Agronomist and Plant Pathologist

Corn fields in many areas of the state are vulnerable to greater than expected harvest losses due to damage from European Corn Borer. Some producers have already decided to begin harvest even though moisture levels are high. Fortunately, the growing season of 1995 allowed for faster than normal corn development and overall grain moisture is somewhat lower than normal.

Producers who are thinking about harvesting grain at wetter than normal moisture will need to address the trade-off between earlier harvest and increased drying costs of wetter corn. Early harvest might be necessary to minimize losses from dropped ears and stalk breakage. Producers need to weigh their own expected yield levels, LP gas and electrical prices, corn prices and moisture percentages to evaluate the economics of different alternatives. A good reference is "Economics of On-Farm Corn Drying" found in the National Corn Handbook (NCH-21).

Another concern is high levels of Fusarium/Gibberella. This fungus has already been a problem in sweet corn fields in east-central Wisconsin. According to Gene Smalley, ".. there is lots of Fusarium inoculum around in 1995 ..." Growth of Fusarium is favored by dry, warm weather while the sexual stage, Gibberella, is favored by cool, humid weather. Both forms are often associated with ear damage from insects, such as European Corn Borer. The fungus is light pink to reddish in color beginning at the ear tip and progressing towards the butt.

This fungus can produce mycotoxins which lead to animal performance problems such as feed refusal, vomiting, and estrogen syndrome. 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.

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