This summer, Raffa is increasing the number of traps per acre. The new traps are light, easy to use, and readily available, he notes. The goal of the research is to determine weevil threshold levels under practical conditions where eventually growers themselves would deploy the traps and monitor for weevil numbers, says Raffa. Several companies are interested in the potential use of nematodes as a biological control against pine root weevils. Nematodes are tiny worms that infect the weevil larvae and adults.
Infection can kill or sterilize the weevils.
Raffa will begin trials next spring to determine the effectiveness of nematodes in controlling weevils and the best time to apply the nematodes. The traps could work well in conjunction with the release of nematodes into the soil, he says. Raffa adds that growers support testing the potential of nematodes to control root weevils but first want to see if they work. Raffa's work is tied with Wisconsin's Christmas tree integrated pest management program to reduce pesticide use. Disease and pest scouting are part of the holistic approach that includes selecting disease-resistant seedlings in an overall management program.