2004 Wheat Stem Sawfly Map

A survey of wheat damage by the wheat stem sawfly was conducted after harvest in 2004. The results suggest this insect will remain a major threat to wheat in 2005. The proportion of wheat stems cut by sawflies was counted at four positions near the margins of selected fields from late August to October 2004. Damage levels were considered severe if more than 25% of the stems were cut by the insect, moderate if they ranged between 10-25% and light if they were under 10%. Because of the reproductive potential of the sawfly, stubble from a crop that sustained even 20% cutting the previous year can produce enough sawfly adults in the following summer to cut over 80% of a crop of hollow-stemmed wheat planted nearby. Non-host broad leaf crops will not be damaged and growing a solid-stemmed wheat varieities will substantially reduce damage below economic levels.

The map shows that the risk of damage in 2005 will continue to be high in the brown and dark brown soil zones of the province. Furthermore, the sawfly will pose a risk in some areas that traditionally have not experienced high levels of damage including some areas near Claresholm, Stavely and south central areas east of Drumheller. No sites were surveyed in northern areas south of Lloydminster where the insect may also reach damaging populations in some years. Damage risk is expected to be light in the thin black soil zones near Calgary.

Many thanks to all the collaborators that conducted the survey of sawfly damage in 2004. For further information about this survey in Alberta contact Hector Carcamo (carcamoh@agr.gc.ca) and for Saskatchewan, Owen Olfert (olferto@agr.gc.ca)

Survey Credits: AAFC, AAFRD, Agricore United, County of Lethbridge, Southern Applied Research Association, Chinook Applied Research Association

Contact the Alberta Ag-Info Centre for more information at 1-866-882-7677

This document is maintained by Shelley Barkley.
This information published to the web on March 22, 2005.