Integrated Pest Management for Raspberries

The above chart compares egg laying periods during the 1997 season for newly-emerged clay colored and black vine weevil. Note that the clay colored weevil, also known as the bud weevil, lays its eggs much earlier in the season than the black vine weevil. To optimize weevil control, insecticides targeting adult weevils should be applied after most adult weevils have emerged from the soil and prior to the onset of egg laying. Careful field monitoring will help determine which species are present and timing of adult weevil emergence from the soil. This chart represents observations from one season only and is not intended as a tool for precise pesticide timing on a regular annual basis. Work is underway to correlate weevil development with soil and air temperature which will support the development of predictive models for these pests. Predictive models combined with field monitoring will allow for more precise timing and improved weevil control. (Data courtesy of WSU Lynden Research Facility.)

Footnote: Recent studies at WSU Lynden Research Facility show that over-wintering black vine weevil adults are capable of laying eggs in April and May, which preceeds the egg-laying period of summer adults shown in this chart.