Canada’s corn growers are “slipping significantly” in following the requirements for a non-Bt refuge when planting Bt corn, a pest management stakeholders’ group warns.
The Canadian Corn Pest Coalition, which includes academics, extension and research staff, regulators, corn growers’ associations and the seed industry, said in a release last week that refuge compliance dropped to 61 per cent in 2009 from highs of up to 80 per cent in 2005.
“We call on the corn industry across Canada to do the right thing and promote the planting of a proper refuge to minimize the risk of insects developing resistance,” coalition chairman Art Schaafsma of the University of Guelph said in the group’s release.
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Refuge requirements for insect-tolerant crops such as Bt corn are meant to encourage low levels of survival among insect pests, preventing the pest population from developing resistance by diluting any resistant traits some insects may carry.
For example, varieties of Monsanto’s Bt corn brand, YieldGard, currently require a minimum of 20 per cent of a farmer’s total corn acreage to be planted to non-Bt refuge varieties.
“Failure to follow IRM (insect resistance management) requirements and properly plant a refuge may result in the loss of access to YieldGard and YieldGard VT corn technologies,” Monsanto Canada warned in a fact sheet for growers last spring.
If corn pests become resistant to Bt proteins, the pests could become “increasingly detrimental” to yields in several crops, since there would be fewer options to control their populations in either conventional or organic crops, the coalition said.
“Misuse”
The Canadian Food Inspection Agency, which regulates novel plant traits, sees the potential for shifting pest status as a “key area of emphasis,” the coalition said.
According to the coalition, CFIA has asked the providers of the seed technology to set up and put in place “corrective action plans to get farm compliance back to acceptable levels.”
Also, the coalition warned, the corn industry can expect “increased scrutiny” by technology providers and the CFIA on refuge compliance “down to the farm field level.”
“These technologies are approved by the CFIA on condition that (seed companies) ensure that users maintain proper refuge area and configuration on farms,” Schaafsma said.
“Continued non-compliance in terms of the use of refuge could result in the availabilities of these technologies being put at risk. We cannot afford to lose Bt corn technology because of misuse.”
As more Bt traits become available, the coalition warned that refuge requirements may become “trait-specific” and vary significantly, so growers must check with the seed provider on the correct refuge to use.
“In no instances” are there any approved corn technologies with refuge included in the bag, the coalition noted, adding that mixing non-Bt and Bt seed is prohibited.”
Current stewardship requirements for Bt corn require a “structured” refuge, in which non-Bt corn is planted in strips, blocks or the perimeter within a Bt cornfield.
A “non-structured” refuge is used when seeding midge-tolerant wheats such as AC Goodeve and AC Unity, which are sold in blends with non-midge-tolerant varieties. But the “refuge-in-a-bag” approach isn’t yet approved for corn.
