Farmers are warned not to spray the pesticide malathion in granaries where they store canola or they risk losing sales to Japan, Canada’s top canola customer.
John Mayko, an agronomist with the Canola Council of Canada, said malathion has been detected in prairie canola destined for export. The oilseed is believed to have become contaminated when the pesticide was sprayed in grain bins.
The discovery of malathion in canola seed was a surprise to the industry, said Mayko. Malathion is not registered for controlling insects in stored grain and although registered for in-crop use, is not often used for field spraying.
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“Initially we tried to find out where residues were coming from because there is very little malathion used in in-crop on canola.”
Mayko said the likely source of malathion is farmers treating their grain bins to stop problems with stored-grain insects in cereal crops.
“If they end up storing canola in the bins treated with malathion, then that’s likely where it’s coming from.”
The problem arises in canola because malathion is absorbed in the oil of the crop. There is not a problem of absorption of malathion in cereal grains.
Malathion applied directly to the seed or onto bin walls moves into the canola seed. Canola should not be stored in bins treated with malathion for at least six months to one year.
Mayko said the Japanese industry is concerned about pesticide residues. The Japanese government has introduced new food safety legislation that will prohibit entry of any commodities if pesticide residues are found above the allowable limit.
“We could potentially end up damaging our highest price export market.”
If malathion is detected above the allowable limit in Japan, the shipment will be rejected. Canada exports more than $450 million worth of canola to Japan each year.
Mayko said Canada has not had a problem yet with excess malathion residue levels in canola seed to Japan, but the industry wants to take steps before it happens, especially when grain-storage insects were a problem during the past winter.
Shipments of canola to Japan with excess pesticide residue levels from Australia cost that country millions of dollars in damage and lost sales.
To help canola growers keep track of which bins were sprayed with malathion for insect control, the canola council is sending producers stickers to paste on the bins as a reminder of which are safe to store canola.
If farmers want to treat their grain bins before storing canola they can use diatomaceous earth, a product registered for use in canola storage.
