The concern about ear mold in late-harvested corn is higher than normal this year following a drought that created conditions ripe for the development of Aspergillus ear rot, an Ohio State University Extension plant pathologist says.
Drought-stressed corn is more susceptible to infection by Aspergillus flavus, an ear rot fungus that produces a very potent group of carcinogenic toxins, called aflatoxins.
Aflatoxins can be harmful when present in both livestock feed and food for human consumption, says Pierce Paul, a researcher with the Ohio Agricultural Research and Development Center.
Harvests delayed by excessively wet fall conditions following summer drought are especially concerning if aflatoxin is present because delaying harvest can increase aflatoxin contamination, Paul says.
“Stalk, root and ear rots may also cause considerable damage in fields waiting to be harvested,” he says. “Root and stalk rots leave plants weak and highly vulnerable to lodging, while ear rots may lead to grain contamination with mycotoxins.”
Other examples of toxins produced in moldy ears are deoxynivalenol (vomitoxin or DON), zearalenone and fumonisin.
But not all ear molds are associated with mycotoxin contamination, Paul cautions.
“Don't just abandon your field if it looks dark and moldy,” he says. “Some opportunistic fungi grow on the husk without affecting the grain. These typically leave the ear looking dark and discolored, but when the husk is removed, the grain looks healthy and normal.
“If you see the ear looking ugly, don't assume you do or don't have ear rot. Pull the husk back and take a look at what is going on.”
To know for sure, Paul says it's best to pull multiple ears from around the field to send to an approved lab for testing. Doing so will determine whether aflatoxins or other toxins are present and whether they exceed thresholds established by the Food and Drug Administration.
More information on aflatoxin testing and FDA thresholds is available at http://tinyurl.com/97owb7f .