Blog: The Wheat Sheaf

Protect the One and Only Sm1 Gene

Anyone who has grown Midge Tolerant Wheat is familiar with Sm1 – the single gene responsible for midge tolerance. Growers of Midge Tolerant Wheat count on Sm1 to protect their crop yield and quality and follow specific stewardship practices to preserve its effectiveness. If tolerance is lost, it could cost growers $60 million annually and up to $36 per acre.

Sm1 was first identified in soft red winter wheat varieties. In the late 1990s, Canadian public breeders worked to cross the naturally occurring trait into red spring wheat (CWRS and Extra Strong) for the benefit of western Canadian producers. These first products were launched in spring 2010 (AC® Unity VB, AC® Goodeve VB, AC® Glencross VB). Since that time, over 20 varieties of Midge Tolerant Wheat have been registered in many classes, including CWRS, CPSR, CWES, CWAD, and GP/SP.

Recently, the Sm1 gene was identified as naturally occurring in the majority of Soft White Spring (SWS) wheat varieties, including: AAC Awesome (CWSP), AAC Chiffon, AAC Indus, AC® Sadash and AAC Paramount. The fact that these varieties have been grown without a refuge until now puts the Sm1 trait at risk. For this reason, growers of these SWS varieties also need to follow stewardship practices for the benefit of all wheat producers. 

Producers can either source SWS seed with the refuge added or voluntarily add the refuge variety – AC Andrew – to their existing supply. One bushel of AC Andrew to every 9 bushels of tolerant SWS variety is the required ratio. If you’re unable to source seed or add the refuge, spray insecticide to eliminate the possibility of resistant midge.

By following these stewardship practices, you will help preserve the effectiveness of the Sm1 gene and support your fellow wheat growers who rely on this technology. You never know when you’ll need Sm1 or the next revolutionary trait so we all have to show leadership through stewardship.

Midge Tolerant Wheat Stewardship Agreements Now Online & Evergreen

All Midge Tolerant Wheat is sold to farmers under a Stewardship Agreement in order to ensure proper stewardship of the technology, which limits the use of farm-saved seed to one generation past Certified seed.

This condition is critical because wheat midge may attack the refuge variety and the level of the refuge in farm-saved seed can change substantially over multiple generations. For example, under an extremely heavy midge infestation, the susceptible refuge variety could sustain up to 50 percent yield loss. To keep the refuge at the desired level of 10 percent of the plant population, it is necessary to limit the use of farm-saved seed to one generation past Certified seed.

Earlier this year, the Midge Tolerant Wheat Stewardship Team launched an online system to improve the Stewardship Agreement process for growers and retailers that will help to ensure continued protection of the Sm1 gene.

The Midge Tolerant Wheat Stewardship Assurance Site (MTWSAS) is a secure, web-based tool for use by seed distributors, seed retailers and seed growers that makes the process of documenting the movement of Certified Midge Tolerant Wheat seed more efficient. With MTWSAS, the stewardship principles do not change, but the process becomes a lot easier. 

This online Agreement replaces the paper-based version and manual process used since the launch of Midge Tolerant Wheat in 2009. The Agreements are signed digitally and evergreen – farmers will only need to sign once, no matter where they buy their seed.

The Midge Tolerant Wheat Stewardship team encourages growers to stop in at their seed dealer and sign their Agreement today. Just a few minutes with your dealer will save you a lot of time and effort when seeding starts and ensure continued protection of the one and only midge tolerance gene.

This article was written and provided by the Midge Tolerant Wheat Stewardship Team - a broad industry coalition representing plant breeders, government, seed growers, seed distributors and producer groups.

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