Vigilance urged as region spared worst of corn mould
Eastern Ontario has been spared the worst of a corn mould infestation that has had a “catastrophic” impact on some producers in the province.
But specialists stress the need for vigilance as a vomitoxin, deoxynivalenol, or DON, has spoiled large volumes of corn.
Tests conducted during the corn ear mould and mycotoxin survey found one elevated sample in the eastern region of the province. Mould content levels were ranked from A to C, with a C sample denoting a level of 2 parts per million or more. Only one crop in Eastern Ontario had a C ranking, according to the tests of 146 corn ear samples that were collected across the province from September 21 to 28.
All of the other approximately 25 samples in Eastern Ontario identified A and B levels, readings that were under 2 ppm.
Overall, visual mould symptoms were more apparent this year and vomitoxin analysis revealed a greater incidence of samples with elevated DON concentrations, according to the survey carried out by the Ontario Ministry of Agriculture, Food and Rural Affairs, Grain Farmers of Ontario and the Ontario AgriBusiness Association.
“While 60 per cent of samples tested below 2 ppm, it is important to remember that growers should remain vigilant and be aware of management options in those fields with higher ear mould and DON concentrations,” reads the report co-authored by crop specialists Ben Rosser and Albert Tenuta.
Corn ear moulds such as Gibberella and their corresponding mycotoxins occur every year in Ontario. These mycotoxins, particularly vomitoxin (DON) produced primarily by Gibberella/Fusarium ear moulds can be disruptive when fed to livestock, especially hogs.
“As we have seen in previous years when environmental conditions were favourable for disease development, the Ontario grain industry has been prepared and able to process corn with minimal impact,” the specialists say.
At the same time, they caution, “This survey does not fully capture all regions of the province, and results can vary locally from field to field depending on hybrid, planting date, insect feeding, rotation, residue levels, fungicide practices and moisture. These results may not fully capture what is occurring in your fields, and therefore monitoring is recommended.”
Timely harvest is important. Leaving diseased grain in the field allows the ear rot fungi to keep growing, which will increase the risk of mouldy grain and mycotoxin contamination since most ear rot fungi continue to grow (and potentially produce mycotoxins) until the grain has less than 15 per cent moisture. In severely infected fields, growers should consider harvesting grain at higher moisture and then dry it to less than 15 per cent to minimize further mycotoxin accumulation.
If a field contains a significant level of ear mould, producers are advised to collect a representative sample prior to harvest and have it tested for mycotoxins before storing the grain or feeding it to livestock.
A lab test is often the only reliable way to definitively determine mycotoxin presence and levels.
DON infects corn, wheat and barley. If ingested, animal feed made from DON-infected grain can cause major health issues for livestock, while farmers can also suffer serious medical problems if the mould is inhaled.
Ethanol producers and distilleries can’t sell byproducts from the infected corn.
GFO President Markus Haerle, a producer from St-Isidore, recently observed: “Although we have yet to see all the end results, we know that the current DON situation is catastrophic for some of our farmers.” Preventing ear rots and mould can be difficult since weather conditions are critical to disease development.
Looking ahead to 2019, producers are reminded that hybrid selection is important but while some tolerant hybrids are available, none has complete resistance.
Growers are encouraged to discuss with their local seed supplier what ear mould tolerant hybrids are best suited for their operation. Crop rotation can reduce the incidence of ear rots, while several fo- liar fungicides aimed at suppressing ear rots have also been registered. Cultural practices such as tillage have been shown to have limited success in preventing ear and kernel rots.
SIGNS OF TROUBLE: Ears show the various species of mould that can affect corn.