This is not a forecast. It is a summary of the pea leaf weevil situation in Alberta in spring 2021.

Methodology

The annual pea leaf weevil (Sitona lineatus L.) survey was completed in late May and early June 2021. It is based on damage ratings in 225 fields from 58 municipalities.

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

Survey findings

The highest damage ratings were in a few fields around Edmonton. There were a couple of hot spots in southern Alberta, but nothing like we have seen in previous years.

Overall, pea leaf weevil numbers are lower that seen in previous years. This could be due to the dry growing conditions, especially in southern Alberta.

Numbers remain very low across the Peace region. Damage was found in 10 out of 38 fields in the Peace, 9 of those with only 1 or 2 feeding notches on 50 plants, with no notching on the clam.

Producers should use the information generated from this survey, along with their own experience to plan control strategies such as seed treatment for the 2022 crop year. Research has shown that seed treatment is much more effective in reducing losses from pea leaf weevil than foliar treatments.

Spring weather conditions

Spring weather conditions have a very large impact on the timing and severity of pea leaf weevil damage. When warm conditions (greater than 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, PLW’s arrival can be much later and the resulting yield impact is lower especially when the crop advances past the six-node stage before weevils arrive. In every case, control decisions should be made on a field-by-field basis.

Find out more about the pea leaf weevil life cycle.

Since 2014, significant pea leaf weevil damage has been seen on faba beans 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 faba beans. The true economic damage of pea leaf weevil on both peas and faba beans on the higher organic matter soils of central Alberta is not well understood, but research has been initiated to work out these relationships.

Acknowledgements

Thank you to Farming Smarter, Chinook Applied Research Association, Lakeland Applied Research Association, Battle River Research Group, Gateway Research Organization and SARDA Ag Research for your contribution to the survey. Thank you to David Giffen, AAFC-Saskatoon for the creation of this map.

Historical population maps

2021 Survey Map (PDF, 225 KB)

2020 Survey Map (PDF, 855 KB)

2019 Survey Map (PDF, 2.2 MB)

2018 Survey Map (JPG, 1.7 MB)

2017 Survey Map (JPG, 160 KB)

2016 Survey Map (PDF, 3.1 MB)

2015 Survey Map (PDF, 275 KB)

2014 Survey Map (PDF, 938 KB)

2013 Survey Map (PDF, 973 KB)

2012 Survey Map (JPEG, 54 KB)

2011 Survey Map (PDF, 480 MB)

2010 Survey Map (JPEG, 50 KB)

2009 Survey Map (PDF, 34 KB)

2008 Survey Map (PDF, 128 KB)

Resources

Pea leaf weevil – Overview

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