Monitoring and Controlling the Beet Leafhopper Circulifer tenellus in the Columbia Basin

Abstract

The beet leafhopper (BLH, Circulifer tenellus Baker) is a frequent pest of potatoes in the Columbia Basin of Oregon and Washington. Beet leafhoppers vector the causal agent of potato Purple top disease, known as Beet Leafhopper Transmitted Virescence Agent (BLTVA). Over 70 % of BLH in the region can be infected with BLVTA. Current control methods include making regular insecticide applications beginning in May; however it is unclear if those applications are needed. Thus, are insecticide applications necessary to control BLH and reduce BLTVA through the entire season? To answer that question, a field study was conducted in 2008 and 2009 to assess season-long control of BLH. There were 14 treatments, including the control, that were based on gradually eliminating insecticide applications weekly. Plots were sampled weekly for BLH and surveyed for Purple Top disease. Beet leafhoppers were sampled using sweep nets and an inverted leaf blower. Natural BLH populations were low in 2008 and 2009, but differed significantly among treatments in 2009 for inverted leaf blower and sweep net samples. Yields were assessed at the end of each season and no significant differences were found. Trends in the yield, BLH populations and BLTVA incidence support early-season insecticide application when BLH populations are low. The practice of using a calendar spray regime was not supported as yields were similar regardless of insecticide applications. As BLH populations were low, the results emphasized the importance of monitoring before making insecticide applications.