A combine in one field I visited this fall was covered with black, flaky material, pretty much all over the machine. The field didn't appear to have stalk rot or much leaf disease, so the black covering was just assumed to be from the decaying fodder.
Steve Wettschurack, a farmer and assistant with the Purdue University Extension farm safety team, says it's likely more than just from decaying leaf tissue. He suspects it's a mold common on ear tips. That would make sense because this particular field was filed with ears that had about inch or more of blank ear tip on every ear.
The field still yielded well, but it could have yielded even more with more rain in August and more nitrogen. The ear tips contained fertilized kernels which aborted once the plant began to search for nutrients to finish the kernels which were further along. Within a two-week period, ears dropped about 6 to 8 kernels on every row around the ear. If three kernels per ear is a bushel per acre, that means it may have easily cropped 20 to 30 bushels per acre just due to the fact that tips didn't fill.
The mold dust isn't a particular problem unless you are allergic to corn molds, the specialist says. In that case you may want to obtain an N-95 paper mask, either with one or two bands to hold it in place, so that you aren't exposed as much to the mold. The same mask will also work if you're cleaning out a bin with lots of dust or in any situation where there is dust which might contain mold.
Protecting yourself and your respiratory system is important as you want to avoid down time and stay healthy during harvest, without interference from respiratory ailments, he concludes.