We have been reading reports of ear mold in corn this fall as well as risk of vomitoxin contamination. But it may turn out to be more risk then reality. And while mold finds are high, confirmation of Gibberrella ear rot is less, vomitoxin finds are even less and finds of vomitoxin at 5 ppm or higher are even less.

Gibberella ear mold. Courtesy Alison Robertson at Iowa State University.

Gibberella ear rot is caused by the fungus Gibberella zeae, also known as Fusarium graminearum which causes scab in wheat. Infections occur more commonly in cool, wet weather after silking and through the late summer. And during an especially wet fall ear rots can envelop the whole ear. Gibberella can produce vomitoxin and zearalenone.

Marcia McMullen, extension plant pathologist at North Dakota State University said "Field moisture above 18 percent to 20 percent for a long time and temperatures above 45 degrees generally favor ear mold development."

She explained that the NDSU diagnostic lab received 40 samples of molded ears and 83 percent tested negative for vomitoxin. Two tested for a toxin known as T2 and one tested for zearalenone. She added that 4 samples tested positive for vomitoxin but was under 2 ppm so it wasn't even a risk. "These molded samples predominately had black superficial, nontoxic mold present that are not associated with mycotoxins. As far as I can tell vomitoxin is not a risk."

Greg Lardy animal scientist at NDSU said the FDA has advisory levels for each group of livestock and each major mycotoxin. "Livestock producers should exercise caution when molds are present, especially with gestating and lactating animals. Visual observation cannot detect the presence of toxins, so testing is advised before feeding moldy feeds. Once the level of toxins are determined, appropriate feeding recommendations can be implemented."

"The biggest problem is quality, low test weight, high moisture and mold damage," said McMullen. "There are some real bad fields of corn and some isolated pockets of mold."