Corn Ear Mould and DON Survey Results for 2008

There are various pathogenic fungi which are responsible for the various ear moulds in Ontario and some such as Gibberella have the potential to produce mycotoxins which can have detrimental consequences if feed to livestock. Although every year is different, there often are fields where ear mould problems do occur each year. The persistent wet weather in certain parts of the province this summer in conjunction with other factors such as leaf diseases, insect injury, bird damage, hail injury, etc could have provided these corn ear rot fungi with the favourable growing conditions necessary for disease development.

For these reasons, the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) in conjunction with the Ontario Corn Producers Association (OCPA) collected 88 corn samples (20 ears per sample) from across the province between October 3 to October 10, 2008 in order to determine visual ear mould and vomitoxin (DON) levels. In previous years, OMAFRA, the OCPA and the University of Guelph Ridgetown Campus have demonstrated proactive surveys such as these are effective in predicting potential problems.

Results shown in Table 1 indicate an average, across the province, of 26% of the ears sampled had some visual ear mould. All samples were dried, shelled and the grain when tested resulted in an average DON concentration of 1.1 ppm and 85% of the samples were below the critical 2ppm level. These results are significantly lower then in 2006 which bodes well for the industry and producers.

As in previous years, the frequency of finding fields with DON levels above 2ppm decreases as you go from southwestern to eastern Ontario. Microclimates and hybrid selection have consistently been important factors in predicting DON and mould problems and this year is no exception. Areas closer to the north shore of Lake Erie or Lake St. Clair tended to have the greatest number of fields above 2ppm.

The survey results reemphasize the importance of hybrid selection and the variability amongst hybrids. For example, two hybrids grown side-by-side in the same location could differ by as much as 4ppm. For producers with recurring ear mould problems, hybrid selection continues to be one of the most important management tools available to you.

Although this survey is limited in scope the results do provide optimism for the 2008 corn crop. However, it also indicates there will be potentially elevated vomitoxin levels in some fields within certain areas of the province Ontario corn producers, should remain vigilant in examining fields for signs of ear mould and testing for the presence of mycotoxins. This will allow for the implementation of grain harvest, storage, marketing and feeding strategies to minimize negative impacts.