Check Fields for Foliar Diseases and Ears Molds Now
Posted: September 4, 2012
We are now seeing foliar diseases in both corn and soybeans at high enough levels to be able to determine what fields have real issues. Scouting now will give you the information you need to make decisions about crop rotations, hybrid and variety selections for next year and subsequent years, and possible tillage. If you have significant amounts of diseases such as Northern Corn Leaf Blight or Frog Eye Leaf Spot, you know that you should plan to purchase genetics that include a good level of resistance to these diseases in the future. The vast majority of the pathogens we face in field crops survive in crop residue from year to year.
As long as you’re walking around your fields, check corn ears for molds, too. We are hearing a lot of reports from the Midwest about higher than normal levels of aflatoxins due to the dry season we have had. This is not commonly a problem here in PA due to our humidity, but there are a few other molds that we might encounter. It is not a bad idea to find out what’s lurking under the husk.
Most of the mold that we tend to have every year is readily removed by the combine. But if more than approximately 10 percent of ears in a field have a significant amount of mold (25 percent of the ear or more), these are probably best harvested as soon as possible for grain. This is because the best way to stop fungal growth is to dry corn to 13% moisture or less (and less than 70°). This won’t eliminate the mold or toxins already present, but will prevent further growth and toxin production in storage. The longer the crop is in the field, the more opportunity there is for mold to develop and spread.
Since ear corn continues to dry in cribs, it can be harvested at 21% moisture or lower. High moisture ear or shelled corn will heat up in storage and allow molds to spread quickly. Bird, insect or combine damaged kernels are also at higher risk for mold development in storage. If at all possible, try to clean out damaged kernels during harvesting and remove fines with a rotary cleaner. Keep good grain separate from highly contaminated grain and test for toxins. It may be possible to feed some of this to animals less sensitive to mycotoxins.
- Research Associate, Southeast Ag Research and Extension Center