2017 Pea Leaf Weevil Survey

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Evidence of feeding in 2017 once again was over a wider range than in previous years. The range of pea leaf weevil activity has expanded dramatically in central Alberta since 2013.

The annual pea leaf weevil (Sitona lineatus L.) survey was carried out in late May and early June, 2017.The 2017 survey was based on damage ratings in 203 fields from 46 municipalities.

Survey locations shown with black circles had no evidence of pea leaf weevil feeding on any of the plants assessed.

In each field the total notches per plant are counted on 50 plants (10 plants in 5 locations near the field margin). The damage rating for a particular field is the average number of notches per plant. It is important to note that although this survey concentrates on adult damage, yield losses are caused by the larval damage to the nitrogen fixing root nodules.

Information about the pea leaf weevil and its life cycle can be found here.

Range expansion of pea leaf weevil from 2012 to 2017.

Overall the severity of pea leaf weevil feeding damage was slightly lower compared to 2016. The most obvious reduction in adult damage by pea leaf weevil was Wheatland and Kneehill counties east to the Saskatchewan border in south-central Alberta. Adult damage was slightly lower in Lethbridge county but east towards Medicine Hat was higher than in 2016.

Pea leaf weevil is now established from southern Alberta through west-central Alberta as far as Barrhead County northwest of Edmonton. Parkland, Lac Ste. Anne, Westlock and Barrhead counties all experienced higher pea leaf adult feeding than in 2016. Sturgeon and Strathcona counties were similar to slightly higher than 2016 but Lamont county still remains relatively low in pea leaf weevil activity.

The survey also shows that pea leaf weevil is now found in all counties to the east of Edmonton including Bonnyville and St. Paul. The survey was also expanded into the Peace region including Greenview, Smoky River and Big Lakes with very low levels of feeding notches found in all three areas. The presence of the weevil in the Peace Region was confirmed later in the season by researchers from the University of Alberta.

While this is not a strict forecast, experience has shown us that activity levels greater than 9 notches per plant is sufficient to cause significant damage if conditions are favorable in the spring of 2018. This covers a large area of southern and west central Alberta. For any producers south of Highway 9 and along Highway 2 up to Edmonton there is a risk of damaging levels of pea leaf weevil in 2018. Producers should use this information along with their own experience to plan control strategies such as seed treatment for the 2018 crop year. Research has shown that seed treatment is much more effective in reducing losses from pea leaf weevil than foliar treatments.

In addition, since 2014 significant pea leaf weevil damage has been seen on fababeans in a much larger area than shown in this survey that is conducted on field peas. This insect causes as much or more damage on fababeans. The true economic damage of this insect on both peas and fababeans on the higher organic matter soils of central Alberta is not well understood but research has been initiated to work out these relationships.

Based on studies of pea leaf weevil biology, moisture in August appears to be a significant predictor of increases in the population. Together this information suggests that pea leaf weevil has the potential to be a very important pest in 2018.

Spring weather conditions have a very large impact on the timing and severity of pea leaf weevil damage. When warm conditions (>20 C) persist for more than a few days in late April or early May the weevils arrive in fields early. Early arrival corresponds to the potential for higher yield losses. In years where cool weather persists, the arrival of PLW can be much later and the resulting yield impact appears to be lower especially when the crop advances past the 6 node stage before weevils arrive. In every case control decisions should be made on a field by field basis.

Life cycle information

Frequently Asked Questions

Historical pea leaf weevil survey maps from 2008-2017.

Feeding damage on faba bean
Shelley Barkley, Alberta Agriculture and Forestry
Pea leaf weevil and feeding damage on field pea
Shelley Barkley, Alberta Agriculture and Forestry
Feeding damage on seedling alfalfa
Shelley Barkley, Alberta Agriculture and Forestry

The 2017 pea leaf weevil survey was carried out by Alberta Agriculture and Forestry staff.

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

Thank you Jan Lepp, Alberta Agriculture and Forestry for managing the data from this survey.

For more information on this insect and its management contact the Ag-Info Centre at 310-FARM (3276) or email bugs.r.us@gov.ab.ca

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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 28, 2017.
Last Reviewed/Revised on December 4, 2018.