Fungal ear rots are not just a problem for areas that were dry this season. Fungal ear rots present a number of problems for farmers, from the potential presence of toxins in the grain, to decreased grain quality, to low test weight, to serious storage issues. Environmental conditions and heavy insect pressure generally conspire to produce a lot of exposed, damaged ears. These are huge predisposing factors for ear rot infection. Late season rains have also presented an ideal environment for deterioration of the grain by fungal rots.

We hear a lot about the toxins produced by the Aspergillus fungus particularly in areas that were droughty but Aspergillus is not the only ear rot to be concerned about and it's not the only one that produces toxins. There are numerous ear rot fungi and each prefers a bit of a different environment to be successful.

In our area Fusarium ear rot and Diplodia ear rot are our most typical ear rots. Fusarium ear rot is the most common ear rot we find in Illinois and the Midwest. Fusarium ear rot is characterized by pinkish to salmon colored fungal tissue growing on the kernels. The fungus can be scattered on the cob or often seen toward the middle of the ear. The color is distinctive. Fusarium ear rot like Aspergillus produces toxins called fumonisins. Fusarium is favored by hot and dry conditions at pollination and high humidity and we had a lot of both of those this season. Diplodia ear rot is first noticed by a bleached appearance of the husk. When you peel back the husk, you will see a white, fluffy fungus. The good news is that the Diplodia fungus will not produce toxins in the grain, but the bad news is that kernels will be very lightweight and shriveled in appearance.

Fields with ear rots need special attention. What is the right moisture to harvest corn that has had fungal ear rot problems? The answer really depends on several important issues. First what ear rot do you have in the field? This season's weather has provided an excellent environment for the development of Fusarium and or Aspergillus. They are serious pathogens and grain drying is essential. The second issue is what weather is expected? The fungi can continue to develop in the field or in storage at above 18% moisture. If dry weather is expected you can try to save some drying costs and leave the grain to dry a bit longer in the field. If you have moderate infection though and wet weather is expected harvesting and drying to at least 18% is probably your best option.

Because of the ear rot fungi already present on the grain, seed moisture of 18-20 percent or more will set the stage for problems in storage. When ear rot fungi continue growing on stored grain they produce moisture and heat needed for infection by a progression storage fungi. To reduce potential problems from storage fungi, store grain in thoroughly cleaned debris free bins. Aim at storing grain at moisture levels of 13-18 percent to stifle mold growth. Proper aeration is important to prevent the build up of moisture pockets as well. Stay safe as the harvest continues.

Do you really have to dry it? Well, that depends on what you are planning to do with the grain. If you are planning on long storage actually you should get the moisture down below 15-16%. Diplodia is not your biggest worry for storage but the many species of Aspergillus that produce very serious grain toxins, such as aflatoxin, are a concern and they like to grow from about 14-18% moisture.