It took 15 years to breed agronomically competitive wheat lines that can withstand the bite of the wheat midge. Without proper management of the trait we've only got eight to 10 years to enjoy it.

This naturally occurring midge tolerance stems from a single gene -- Sm1 -- which means insects that aren't affected by its expression would soon be too fruitful and multiply, overcoming the resistance in a relatively short period.

Midge tolerance could be available to wheat growers for nine years or 90, depending on farmers' willingness to protect the trait, SeCan's Todd Hyra says. -- Lyndsey Smith photo

"If we manage the trait with interspersed refuges we could maintain this gene's effectiveness for as much as 90 years," says Todd Hyra, the western Canadian business manager for SeCan.

Hyra is part of the Midge Tolerant Wheat Stewardship team, a group that's working to make sure farmers recognize the importance of maintaining this trait. The trait is very effective at killing the feeding larvae, he says, and it's also very cost effective control for farmers. Seeing as the trait was developed with public money, it's in everyone's best interest to protect the trait's effectiveness.

While it's a serious situation, maintaining the trait is relatively straightforward: Each new variety with the midge tolerant trait will only be sold as a blend. Seed lots will be sold with 10 per cent content of another susceptible variety, ensuring the susceptible variety is spread evenly throughout the field.

No weaklings

This allows some midge to survive and breed with those midge unaffected by the Sm1 gene, Hyra says. The resulting offspring are susceptible, for the most part, and the population of susceptible to non-susceptible midge should remain in balance.

The Sm1 gene has been bred into three lines commercially available this year and in another for 2011. "These aren't agronomic weaklings, either," he says, noting that the usual yield or quality tradeoffs that can occur when breeding in a specific trait don't apply here.

AC Unity matched with AC Waskada, AC Goodeve with AC Intrepid and AC Glencross with AC Burnside are available this year. AC Fieldstar blended with AC Waskada will be commercially available in 2011.

All farmers who choose to grow any of these blends will be required to sign a stewardship agreement that allows for only one year of farm-saved seed. After that, it's time to buy certified seed once again.

That's because over time, the crucial 10 per cent susceptible crop will diminish in the mix, allowing midge unaffected by the Sm1 gene to multiply.

More information on the required stewardship agreement and on growing midge-tolerant varieties is available online.

-- Lyndsey Smith is an associate editor with Grainews in southern Saskatchewan.