Sasktatoon, Saskatchewan
April 5, 2007
Four wheat varieties with
resistance to wheat midge were recommended for registration at
the variety registration meetings held recently in Saskatoon.
The varieties promise to dramatically change how producers deal
with this damaging pest. Presently, the only defense against
high wheat midge numbers is a pesticide application.
Developed by wheat breeders from Agriculture and Agri-Food
Canada in Winnipeg and Swift Current, through the support of the
Western Grains Research
Foundation (WGRF), three of the varieties are in the Canada
Western Red Spring (CWRS) 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 Lanette Kuchenski,
Executive Director of the WGRF. “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 ρ-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.” |
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