2015 Pea Leaf Weevil Survey

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The annual pea leaf weevil (Sitona lineatus L.) survey was carried out in late May and early June, 2015. Evidence of feeding in 2015 was over a much wider range than in 2014. The range of pea leaf weevil activity has expanded dramatically in central Alberta and the intensity of damage was much higher in the area centered north of Red Deer.

The 2015 survey was based on damage ratings in 111 fields from 35 municipalities. 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. For information about the pea leaf weevil and its life cycle.

Overall the level of pea leaf weevil feeding damage was lower in 2015. This is especially true in southern Alberta but experience has shown us that the level of pea leaf weevil activity observed is sufficient to cause significant damage if conditions are favorable in the spring of 2016. The most severe damage in 2015 were in areas southeast of Lethbridge and in central Alberta in Red Deer and Lacombe counties. For any producers south of Highway 9 and along Highway 2 up to Leduc there is risk of damaging levels of pea leaf weevil in 2016. In the annual survey, this is the second year of high levels of damage in southern parts of central Alberta and along Highway 2. Producers should use this information along with their own experience to plan control strategies such as seed treatment for the 2016 crop year. Research has shown that seed treatment is much more effective in reducing losses from pea leaf weevil than foliar treatments.

In addition, in 2015 significant pea leaf weevil damage has been seen on fababeans in a much larger area than shown in this survey 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.

Some VERY low levels of feeding damage were once again found in throughout eastern central Alberta. This damage is so low that there is no risk of serious issues with pea leaf weevil throughout central Alberta in 2015. This area is almost exactly the same as previous years and although this is a range expansion the damage ratings are still exceedingly low. It will be important to watch the development of these populations over the next few years. Survey locations shown with black circles had no evidence of pea leaf weevil feeding on any of the plants assessed.

Although this is not a strict forecast, experience has shown us that the higher the damage rating in this survey, the higher the risk of damage in the next year. Based on studies of pea leaf weevil biology, moisture in August appears to be a significant predictor of changes in population. Together this information suggests that pea leaf weevil has the potential to be an important pest in 2016.

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.

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

Life cycle information

Frequently Asked Questions

Historical pea leaf weevil forecast maps from 2008-2015.

The 2015 pea leaf weevil survey was carried out by Alberta Agriculture and Forestry.

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

For more information on this insect and its 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 January 15, 2016.
Last Reviewed/Revised on December 4, 2018.