Neonicotinoids jeopardize Manitoba buckwheat exports

Residue limits exceeded Japanese inspectors reject containers because of the presence of insecticidal seed treatment

Manitoba buckwheat processors are feeling anxious about exports after Japanese inspectors rejected a shipment of buckwheat for neonicotinoid contamination.


Rejean Picard, a Manitoba Agriculture farm production adviser and buckwheat expert, said Japan re-fused two containers of buckwheat grown in Manitoba. The buckwheat exceeded Japan’s maximum residue limit (MRL) for thiamethoxam, an insecticidal seed treatment.


Thiamethoxam, a Syngenta insecticide, is better known by its brand names Helix XTra and CruiserMaxx. The neonicotinoid is applied to canola, corn and soybean seeds in Western Canada.


Picard said the buckwheat with neonicotinoid residue was grown in 2012 and exported in 2013.


“I understand that there were two (containers) that were shipped,” he said. 


“It exceeded the MRL in Japan, so the shipments were refused and returned…. Glyphosate also showed up in the results, but it was within the MRL.”


Marc Durand, a buckwheat grower in Notre Dame de Lourdes, Man., said processors and others in Manitoba’s buckwheat trade can’t understand how thiamethoxam got into a buckwheat shipment.


One possibility is that the crop grown before buckwheat received a seed treatment and the neonicotinoid remained in the soil.


“We’re not sure if it’s residues in the soil or farmers are not cleaning out their equipment properly,” said Durand, while standing at the Manitoba Buckwheat Growers Association booth at Manitoba Ag Days last week.


Picard said on-farm contamination is improbable because producers use specific equipment to handle seed treated with insecticides and fungicides.


“Producers won’t use equipment to load grain that they would use to load treated seed. They usually would have different augers for that,” he said. 


“We haven’t ruled it (contamination) out completely, but we think it’s an unlikely cause…. These neonics are widely used on other crops. We’re thinking possibly the previous crop might have been treated with that. Maybe poor breakdown (of the insecticide) in the soil.”


Buckwheat is an unlikely candidate for testing positive for pesticides because so few chemicals are registered for use on the small acreage crop.


However, nearly every corn, canola and soybean seed in North America is treated with a neonicotinoid. The three most popular neonics are clothianidin, imidacloprid, which are Bayer products, and thiamethoxam.


Christy Morrissey, a University of Saskatchewan toxicologist who has studied neonics, said the insecticides persist in soil for years.


“Neonicotinoids break down very slowly in soil,” she said in an email. 


“Half lives vary by compound and environmental conditions, but data for clothianidin is 300 to 1,400 days…. In Saskatchewan soils, 91 percent of the original compound was still present in soil (after) four to six months.”


Picard said thiamethoxam is registered for use on buckwheat, but that source of contamination is unlikely.


“I’ve never heard of anybody using any seed treatment … on buckwheat.”


The neonic contamination is worrying Manitoba processors about future shipments to Japan, where buckwheat is used to make soba noodles. 


One processor said federal and provincial governments should take the risks associated with neonics more seriously, especially the trade risks. 


Durand said Manitoba processors might not buy buckwheat from growers if Japan refuses more containers for neonic residues.


“It is a big concern,” he said.


“There are not many buyers (in Manitoba) … and if they’re having this risk, they might not take the risk.”


Gord Kurbis, Pulse Canada director of market access and trade policy, said he’s never heard of a Canadian special crop rejected for neonicotinoid contamination. 


He said inconsistent rules for maximum residue levels likely caused the recent rejection in Japan.


“These sorts of things aren’t a story about food safety risks. This is a story about not having coherent international regulations,” he said. 


“No doubt, this is where this buckwheat problem (arose) as well.”


Kurbis said Japan doesn’t have a specific MRL for thiamethoxam and buckwheat, so the country uses a default MRL of 0.01 parts per million. 


In comparison, Japan has significantly higher MRLs for thiamethoxam on other food products. It’s five p.p.m. for cabbage and three p.p.m. for lettuce and beets, which is 500 and 300 times higher than the default levels.


Kurbis said inconsistent rules within countries and varying regulations from country to country force Canadian exporters to navigate through a byzantine system of MRLs. 


“We’re moving (commodities) to 150 countries and there are potentially 30 or 40 actives (pesticides) across a half dozen minor crops and pulse crops. This is a pretty formidable combination,” he said. 


“That risk is taking us into a world where these hypothetical trade risks of having zero tolerances on the books start to morph into real trade risks.”