Harvest is progressing with recent windy, warm, and sunny weather. However, the USDA Illinois Weather and Crops Report estimated that as of November 8th, only 31 % of the corn and 69 % of the soybean crop has been harvested in Illinois. Besides the weather, which has caused crops to mature later and prevent a timely harvest, farmers are facing a variety of other concerns. One such concern is the quality of corn seeds due to wet conditions.
Corn grain, around Illinois and throughout the Midwest, is experiencing a variety of ear molds, such as Diplodia and Gibberella ear rots, which appear to be the biggest problems. However, keep in mind, that other ear rot and opportunistic fungi can also thrive in the wet weather conditions we have been experiencing. Fungi that colonize the grain not only damage kernels and cause discounts at the elevator, but also may produce mycotoxins, natural chemicals the fungus produce, that can harm livestock if the grain is fed.
Dr. Carl Bradley discussed many of the possible fungi attaching corn ears, the risks of mycotoxins from several fungi, and management suggestions in article number 6, issue 24 of the November 6, 2009 Pest Management and Crop Development Bulletin. This can be located online at http://ipm.illinois.edu/bulletin/.
Here are several key points to remember. Firstly, all ear rots can cause problems or discounts for farmers at the elevator because of poor quality and damaged grain, lower test weights, or foreign material such as parts of rotted cobs in the grain. Secondly, the fungus causing Diplodia ear rot is not known to create mycotoxins, however other fungi can also grow on the ear at the same time that may produce mycotoxins. Thirdly, moldy grain should be tested for mycotoxins before feeding to livestock. The Illinois Department of Agriculture's Centralia Animal Disease Laboratory can test grain for mycotoxins for Illinois residents. Information on the lab, its services, and fees can be found online at: www.agr.state.il.us/AnimalHW/labs/centralialab.html. The laboratory is located at 9732 Shattuc Road, Centralia, IL 62801, phone 618-532-6701.
Jim Morrison, U of I Extension Educator for Crop Systems in Rockford, IL, says "it is important to follow general guidelines for collecting and mailing a sample to the Department of Agriculture
Laboratory." Due to the great variation of mold levels within a field or between fields, it is critical to collect a representative sample for laboratory diagnosis.
Morrison adds that, "The Department of Agriculture suggests using a cup or similar container to periodically sample the grain stream from the combine or grain cart. Continue sampling until one accumulates 15 pounds of shelled corn. Mix this amount well and remove a five pound subsample to send to the laboratory. Mail the five pound sample the same day as it is collected, and plan ahead so it can be sent early in the week to prevent the sample from sitting over the weekend." Contact the lab to find out more specific guidelines.
If possible, plan to harvest infected corn fields first. Then, quickly dry the grain down to below 18% for short-term storage, or below 15 % moisture for longer term storage, to help prevent further mold growth in storage.
