Submitted to: Journal of Environmental Horticulture
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/29/2008
Publication Date: 3/1/2009
Publication URL: hdl.handle.net/10113/45365
Citation: Oliver, J.B., Fare, D.C., Youssef, N., Halcomb, M.A., Reding, M.E., Ranger, C.M. 2009. Evaluation of Systemic Insecticides for Potato Leafhopper Control in Field-Grown Red Maple. Journal of Environmental Horticulture. 27(1):17-23. Interpretive Summary: Red maples are one of the most widely grown landscape trees. A few red maple cultivars have some resistance to potato leafhopper, but most cultivars are susceptible. Typical potato leafhopper injury on red maple includes distorted leaf tissue and reduced shoot growth. This research identified systemic insecticides that controlled leafhopper damage up to three years after application, and depending on cultivar, resulted in increased shoot elongation and trunk diameter growth. Several treatment methods and insecticide formulations, such as drenches, tablets and soil-applied gels were evaluated. These methods eliminate drift associated with conventional spray methods. Although systemic neonicotinoids have a higher initial application cost than contact sprays such as pyrethroids, they offer several advantages: fewer applications, control of leafhopper injury for longer periods, prevention of other pests like flatheaded borers, better plant aesthetics, and enhanced plant growth.
Technical Abstract: Systemic insecticides and application methods were evaluated in two tests that began in 2005 and 2006 for control of potato leafhopper (Empoasca fabae [Harris]) on four red maple (Acer rubrum L.) cultivars and rated yearly through 2007. Treatments evaluated in this study included surface drenches of imidacloprid (Discus or Allectus), clothianidin (Arena 50WDG), dinotefuran (Safari 20SG), or thiamethoxam (Flagship 25WG); soil inserted treatments of imidacloprid formulated as a tablet (Merit FXT) or as an experimental gel; or a plant root dip of Discus + Terra-Sorb hydrogel. In the 2005 Test, a one-time drench of Discus significantly reduced leafhopper damage to red maple for a period of 3 yr. In the 2006 Test, a one-time drench of Allectus, Discus, Arena, Flagship, and Safari significantly reduced leafhopper damage for 2 yr. The Discus drench and Discus root dip treatments were initially more effective than the Merit FXT tablets (2005 and 2006 Test) and the gel treatment. However, the efficacy of Merit FXT tablet or gel treatments increased in subsequent years. Two Merit FXT tablets were more effective than one. Likewise, higher imidacloprid drench rates were more effective than lower rates. Most insecticide treatments significantly increased red maple trunk diameter. Allectus and Discus drench treatments significantly increased the branch and internode length of ‘Franksred’ maple in the 2005 Test. Results of this study indicate long-term potato leafhopper control with systemic insecticides and enhanced growth in red maple.