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2020 Ontario Grain Corn Ear Mould and Deoxynivalenol (DON) Mycotoxin Survey

OMAFRA field crop specialists in collaboration with Grain Farmers of Ontario (GFO) and members of the Ontario Agri-Business Association (OABA) have completed the annual Ontario corn ear mould and DON mycotoxin survey. Corn ear moulds such as Gibberella and their corresponding mycotoxins occur every year in Ontario. These mycotoxins, particularly deoxynivalenol (DON, also referred to as vomitoxin) are produced primarily by Gibberella/Fusarium ear moulds and can be disruptive when fed to livestock, especially hogs. The 2020 survey found 89% of samples tested low (<2.00 parts per million (ppm)) for DON which is in line with long term survey averages.
 
Methods:
 
From September 23 to October 2, 2020, 245 ear corn samples were collected from across the province. Five consecutive ears were collected from four random locations throughout a field and placed into high temperature driers (80°C) as soon as possible after collection. Pictures were taken to document moulds (Fig. 1) as well as insect and bird feeding damage. Dry ears were shelled and coarse ground and mixed for sub-sampling consistency. Sub samples were collected and finely ground for DON analysis by quantitative ELISA analysis at the University of Guelph Ridgetown Campus mycotoxin lab.
 
While 89% of 2020 samples tested below 2 ppm, growers should still remain vigilant and understand management options in fields with higher DON concentrations. Ear moulds and mycotoxins occur every year in Ontario and fields need to be assessed individually. Distribution of samples and their corresponding DON levels are presented in Figure 2.
 
Growing Season
 
The growing season remained relatively dry across the province from April through to mid-July. As corn started tasseling mid-July, regular rainfall events occurred for many areas of the province which were good for corn yields but also could provide favourable environmental conditions ( moisture and humidity) in corn canopies for ear mould establishment at fresh silk stage. Frequent rains persisted for several weeks following tasselling. This along with high temperatures may have contributed to ear moulds establishing in fields, particularly those with hybrids known to be more susceptible to  ear moulds, and those with ear feeding damage. Drier conditions through later August and September likely limited ear mould progression in fields where infection was established.  During the survey, corn maturity ranged from half-milk to black layer.
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