Canada Getting Wheat Midge Resistant Varieties

SASKATOON - Apr 5/07 - SNS -- Canadian farmers will soon have four wheat midge resistant varieties available, reports Lanette Kuchenski, Executive Director of the Western Grains Research Foundation (WGRF).

Developed by wheat breeders from Agriculture and Agri-Food Canada in Winnipeg and Swift Current, three of the varieties are in the Canada Western Red Spring (CARS) wheat class and one is in the Canada Western Extra Strong (CWES) wheat class.

"These numbered lines are still two to four years away from commercial production, but when available, they should save farmers a lot of time and money," notes Kuchenski, whose organization helped fund the research. "Western Canadian farmers should be proud that they aided the development of these breakthrough varieties through their support of the wheat and barley check-offs."

Old American soft red winter wheat varieties were the source of the resistance trait. It has taken more than 15 years, but researchers have been able to move the trait into spring wheat varieties that also boast superior yield and agronomic traits.

The wheat midge resistance is produced by the early induction of two naturally occurring compounds within the wheat kernels – ferrulic acid and ñ-comaric acid. Due to these compounds, wheat midge larvae are not able to develop when feeding on the immature kernels. These compounds dissipate by the time the crop has matured.

To prevent wheat midge from developing resistance to the gene controlling this trait, researchers and regulatory bodies are exploring the potential of mixing a small percentage of a susceptible wheat variety with the new resistant varieties.

Called an interspersed refuge, this will allow some wheat midge to survive, thereby reducing the selection pressure for a resistant strain of midge. It will also allow wheat midge parasites to continue having a host. Currently, there is only one gene known which confers resistance to midge. Therefore, it is very important to protect this gene.

Wheat midge was first discovered in Western Canada back in the mid 80's and has been a sporadic problem ever since. The insect caused losses in many parts of Saskatchewan and Manitoba in 2006. Damage by midge was the primary downgrading factor in these 2006 crops, and the pest is expected to cause economic losses over even a wider area this year.

Yield and grade losses from wheat midge are often dramatic. Producers have difficulty knowing which fields have wheat midge numbers that warrant spraying and the application window is short. Insecticide applications need to occur just as the crop is heading in order to be effective.

"Wheat varieties with built in resistance will be a major breakthrough for producers," says Kuchenski. "The payback on the research investment should be dramatic."