Corn Ear Moulds and Mycotoxins:
Update November 6, 2006

OMAFRA, in conjunction with Dr. Art Schaafsma, (University of Guelph – Ridgetown Campus) continue to survey corn fields across the province. Twenty (20) corn cobs were selected from these fields and assessed for the visual mould present on each ear and tested for vomitoxin (DON) production.

Of the 94 fields tested over the past several weeks, 61 or about 65% of the fields were at or below 2 ppm DON, 17 the fields (18%) were in the 2 to 6 ppm range, while the remaining 18 fields (19 %) were over 6 ppm (see Table 1).

However, if you look exclusively at the fields sampled in the extreme southwest portion of the province (Chatham-Kent, Middlesex and Elgin counties) 13 of the 34 fields examined had DON levels over 6 ppm.

The results tend to indicate that there is a significant percentage of the province’s corn that is relatively free of vomitoxin. However, in nearly all parts of the province there are fields that could have high levels of DON and that the chance of this occurring increases significantly in the south-west portions of the province.

Corn with DON levels in the 2-6 ppm may be utilized effectively but will take some additional management (blending, cleaning, combine adjustment, etc). Fields above 6 ppm which if identified for feeding may require alternative plans, segregation or substantial management. The results show that there is a lot of good corn out there in the province but every field is different and needs to be looked at individually before harvesting.

It must be noted that these results represent field samples that were shelled, milled and tested with no drying. Drying, aerating, mechanical movement and cleaning could reduce vomitoxin levels but to what extent we do not know.

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