2010 Pea Leaf Weevil Forecast

The pea leaf weevil (Sitona lineatus L.) increased in severity of damage but the range it is found in has not expanded in 2010. The 2009 survey was based on damage ratings in 92 fields from 22 municipalities. The survey was carried out in late May and early June. For information about the pea leaf weevil life cycle. The survey is based on leaf notch counts on 50 plants per survey field. The damage rating for a particular field is the average number of notches per plant.

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For the second year in a row the pea leaf weevil has not expanded its Alberta range. It was less commonly found in the northern areas of its range as determined in 2007. The Pea leaf weevils range now remains southern Alberta and the southern portion of central Alberta. The survey once again included Red Deer, Lacombe, Settler, Paintearth and Provost counties on the north end and to the US/Alberta border on the south. The weevil and its damage was NOT noted any new counties in the 2009 survey. In areas where the pea leaf weevil is established the numbers of weevils present and the damage they caused were higher than experienced in 2008 although the weevils and their damage in was much later appearing compared with most previous years. This late arrival to pea fields is a direct result of much cooler than average temperatures throughout May.

Although this is not a strict forecast, experience from the last couple of years has shown us that areas with greater than 9 notches per plant (dark tan on the map) have had high levels of damage in the next year. If this trend follows through into 2010 then we can expect the potential for high levels of pea leaf weevil damage in the counties of Willow Creek, Vulcan, Lethbridge, Taber, Warner, Forty Mile and Cypress. Producers in areas with greater than 9 notches per plant should include control options in their pea crop budget for next year. Based on studies of pea leaf weevil biology, moisture in August appears to be a significant predictor of changes in population. This information suggests that pea leaf weevil has the potential to be a very significant pest in 2010.

The control options at this point include Matador as a foliar application and Cruiser as a seed treatment.

Life cycle information

2010 Pea Leaf Weevil Forecast

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