Genetic Resistance Is Just One Part Of Pest Management

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Registration of midge-resistant wheat and the possibility of clubrootresistant canola is welcome news, says Doon Pauly, crop specialist with Alberta Agriculture and Rural Development, Stettler. But he warns that genetic resistance can’t be maintained forever, as insects and disease can evolve and adapt. He says good management and sanitation will remain key to holding the pests at bay.

A clubroot-resistant canola hybrid which is also glyphosate tolerant could be available this spring.”There are, however, regulatory hurdles to cross before the clubroot-resistant canola seed can be sold to farmers because there is insufficient data to support full registration of the variety,” Pauly said in a release. “The general thinking is that this variety will likely be given special registration status because of the significance of the clubroot problem and the potential benefit of genetic resistance.”

Pauly says that although clubroot resistance could be a great new tool, producers should maintain realistic long-term expectations.

“Clubroot-resistant canola, planted on land that is heavily infested with clubroot, will probably lose its resistance very quickly,” says Pauly. “A one-in-four-year rotation of clubroot resistant canola in conjunction with good equipment sanitation practices should keep the pathogen at manageable levels.” He says that every time a resistant variety is grown is one less time that the same genetics can be used successfully in the future.

Midge-resistant wheat will soon be available, perhaps in 2010. In these spring wheat varieties, resistance is due to a single gene. Under normal production practices this single-gene resistance could break down within a decade. To keep this resistance viable for as long as possible, the scientists that developed the varieties have also proposed a system in which resistant wheat seed will be blended with seed of comparable susceptible or “refuge” varieties in a 9:1 mixture. The refuge varieties are an essential part of the pest management system because they allow normal pest mating practices to continue, keeping the populations similar to what they are currently, and thereby minimize the selection pressure for pests that can tolerate the crop’s defence system.

“Although both of these new developments are great tools, they both need to be used as part of an integrated pest management system to ensure that they are effective for years to come,” Pauly says.

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