2017 Wheat Stem Sawfly Forecast

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Sawfly populations increased in some areas and decreased in others based on the 2016 field margin survey. The area most at risk of economically significant sawfly populations in 2017 will be in the Willow Creek /Lethbridge county border. In addition, western Newell County and southern Forty Mile County showed an increase in sawfly populations. Traditional sawfly populations in the Special Areas and the M.D. of Acadia are very low. The population east of Red Deer appears to be in decline.

The damage ratings are based on 102 fields in 22 municipalities.

The population in Paintearth, Camrose and Flagstaff counties is on the decline due to parasitism and also fungal attack of overwintering larvae. Overall the sawfly risk remains low but there are still sufficient numbers to fuel wheat stem sawfly resurgence if dryer conditions occur for consecutive growing seasons.

Despite the low level of sawfly in the survey and because of the random nature of the survey, individual fields may still have higher wheat stem sawfly populations than are indicated in the survey map. Please feel free to contact us if you feel the map does not reflect the situation in your area. Overall there were zero or very low sawfly numbers in 87 of 102 (85%) of fields surveyed. (Field locations denoted by a black dot had zero sawfly found in the survey.)

Eight years of sawfly survey at a glance

The Wheat Stem Sawfly Map is based on cut stem counts conducted after the 2016 harvest. The percent of stems cut by sawfly gives an indication of the number of reproductive adult sawflies that will emerge in late June through early July. Winter conditions have very little impact on sawfly populations and a high proportion of wheat stems cut in the fall will produce adults. Producers in areas with moderate to high levels of cutting should consider using solid stem wheat as a control strategy.

Wheat stem sawfly

Wheat stem sawfly damage

Wheat stem sawlfy larva in stem

Female sawflies lay eggs inside grass and grassy crop stems; the eggs hatch and tunnel inside stems until the crop starts to dry down near harvest. As the crop starts to ripen the sawfly larva migrates to the stem base and cuts a notch most of the way through the stem. Feeding damage from the tunneling can result in hidden yield losses of 10 to 15 percent. Further yield losses can occur from lodging at harvest. More information can be found at wheat stem sawfly life cycle.

It is possible that population hot spots still exist in areas of lower risk, individual producers need to be aware of the potential risks in their own fields.

Cutting levels higher than 10 to 15 percent in the previous crop indicate the need to consider seeding solid stem wheat to reduce sawfly losses. It is important farmers evaluate their individual situations in making their variety choices. When populations are low it is typical to have small localized populations of sawfly that affect only one field or even just a portion of one field.

Bracon cephi
Parasitism can reduce populations and reduce the level of cutting. A parasitic wasp, Bracon cephi, has been shown to have significant impact on sawfly populations.

The use of solid stem wheat varieties and the increase in parasitism are the major factors in lower sawfly populations in Alberta.
Frequently Asked Questions
Economic Thresholds

The 2016 wheat stem sawfly survey was carried out by Alberta Agriculture and Forestry with support from Farming Smarter and Chinook Applied Research Association. Thank you for your contribution.

Thank you Jan Lepp, Agriculture and Forestry, Brooks for managing the data from the field sheet to spread sheet.

Thank you David Giffen, Agriculture and Agri-Food Canada, Saskatoon for building the map.

For more information of sawfly and their management contact the Ag-Info Centre at 310-FARM (3276).
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For more information about the content of this document, contact Scott Meers.
This document is maintained by Shelley Barkley.
This information published to the web on November 30, 2016.
Last Reviewed/Revised on December 4, 2018.