Growers Must Rely on Agronomic Practices, Resistant Varieties to Beat Wheat Stem Sawfly

Cross section of AAC Oakman VB showing stem solidness, which is an important trait to use along with proper agronomics for wheat stem sawfly management.
Imagine driving up to your nearly ripe wheat crop to find plants cut off and lying every which way. Devastating! Was it hail? No, the unwanted pest was wheat stem sawfly and now you are suffering yield losses and mechanical harvest has become incredibly challenging.

The wheat stem sawfly is a stem-boring insect that has been a major wheat pest in the northern Great Plains for more than 110 years. Sawfly damage can result in more than 70% of the stems being cut. Unfortunately, the past few drought-stricken growing seasons have caused a resurgence of this pest.

There are no insecticides to manage sawfly, so growers have traditionally used a combination of agronomic practices and resistant varieties. Historically, growers had options such as Lilian, AC Abbey and AC Eatonia. However, these solid-stemmed varieties are now classified as Canada Northern Hard Red, leaving growers with no solid-stemmed options in the premium Canada Western Red Spring (CWRS) market class. However, this is about to change.

At the 2024 Prairie Grain Recommending Committee (PGDC) meetings, a CWRS solid-stemmed variety, AAC Oakman VB, was supported for registration. AAC Oakman VB, with AAC Brandon as the refuge, was entered in the Alberta regional variety trials in the 2024 growing season and Alberta data will be published in the January 2026 Alberta Seed Guide. This variety was bred by the Agriculture and Agri-Food Canada team at Swift Current under the leadership of Dr. Richard Cuthbert. Distribution rights have been assigned to SeCan and will be available to growers in limited quantities for the 2026 field season.

Thanks to producer funding and initiative, AAC Oakman VB holds a record for development time. The initial cross was made in 2017 and foundation seed for the new variety was planted in spring 2024. A novel agreement was facilitated by the Canadian Wheat Research Coalition to accelerate seed production on this solid-stemmed wheat for western Canadian farmers.

The solid-stem trait helps to reduce wheat stem sawfly populations. Research at Lethbridge has shown that female sawfly that emerge from solid-stem wheat are smaller and lay fewer eggs than sawfly that emerge from hollow-stem wheat.

Winter wheat and durum also experience sawfly damage. There are solid-stemmed durum options such as AAC Grainland, AAC Stronghold, CDC Fortitude and AAC Weyburn VB. Within the CWRS class, there are some semi-solid stemmed varieties: CDC Adamant VB, CDC Landmark VB and CDC Hughes VB that confer partial resistance to wheat stem sawfly.

In situations where there is known sawfly infection, producers should try to salvage the crop by swathing as soon as kernel moisture crops below 40% to save infested stems before they are cut. Future generations of sawfly can also be managed by harvesting early before the larvae move below the cutting height. Harvesting sawfly infested crops for greenfeed or silage are also salvage options.