Preserving The Wheat Midge-Tolerance Trait

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Limits are going to be placed on farmers saving their own wheat as seed. For farmers who are cynical, and we tend to be a cynical bunch sometimes, this will sound like a money grab.

In this case, there’s an important reason. It’s an attempt to preserve the value of new wheat varieties that have resistance to the wheat midge.

In areas that have wheat midge (and that’s a big chunk of Western Canada), producers often have to spray an insecticide to control the pest. Knowing whether you need to spray a particular field requires extensive crop scouting and it’s easy to get it wrong. Not spraying when you need to is costly in terms of lost yield and lost quality.

Three new wheat midge-tolerant wheat varieties will be commercially available starting next spring. It took more than 15 years and a big financial investment for researchers to move the one known gene that confers tolerance into these new spring wheat varieties. Farmers were part of that investment through checkoff dollars paid to the Western Grains Research Foundation.

To preserve the single gene tolerance, farmers interested in planting a midge-tolerant variety will be required to sign a stewardship agreement that limits farm-saved seed to one generation past certified seed.

While that may sound like yet another system to extract more money through certified seed sales, there’s actually a very strong justification.

The varieties are being sold as blends which contain 90 per cent of the midge-tolerant variety and 10 per cent of a regular midge-susceptible variety. This is called a refuge.

With corn varieties that have insect resistance, farmers in the U.S. are required to plant strips of nearby susceptible varieties as a refuge. With wheat in Western Canada, the refuge is going to be interspersed in the population.

The interspersed refuge works to prevent the buildup of wheat midge that are tolerant to the trait. Within the midge population, some of the little buggers will be tolerant. If they’re the only ones that survive, you’ll have tolerant midge mating with other tolerant midge and the whole system will quickly break down.

With the interspersed refuge, the midge feeding on the susceptible variety will live and mate with midge that are tolerant. The resulting progeny is susceptible. This is expected to extend the life of the system from as little as 10 years to 90 years or longer.

If farmers keep using their own seed year after year, the level of the susceptible variety will keep dropping due to damage from the midge. Soon there will be little or no refuge to prevent the midge from becoming tolerant.

The system will be a boost to seed growers. Farmers typically purchase certified seed of a new wheat variety only once and from then on they save their own seed. With this system, producers will be back purchasing certified wheat seed every second year.

Preserving the system hinges on producers understanding the need for the refuge. If producers fail to abide by the limitation on farmer-saved seed, the only known source of genetic resistance will quickly become useless.

Millions of dollars in research investment will be lost and producers will be back spraying insecticides to control the insect.

Explaining the science and need for certified seed is integral to preserving the genetic resistance. A new website was recently launched at www.midgetolerantwheat.ca to provide in-depth information.

Will producers abide by the restrictions? How many will try to save a few bucks by not buying certified seed on a regular basis? The industry is wrestling with these questions. Producer education is the first step, but some enforcement procedures may also be needed.

Kevin Hursh is a consulting agrologist and farmer based in Saskatoon. He can be reached at[email protected]

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