2017 ASHS Annual Conference

Crapemyrtles (Lagerstroemia indica and hybrids) are considered an essential landscape plant in urban and suburban areas of the southeastern US. The crapemyrtle bark scale (CMBS), Acanthococcus lagerstroemiae, a new pest on crapemyrtles, was first detected in Texas in 2004 and had quickly spread to 11 states by 2016. Other than crapemyrtles, CMBS has been confirmed infesting beautyberry (Callicarpa americana) in open field, and pomegranate (Punica granatum), heimia (Heimia salicifolia) and winged loosestrife (Lythrum alatum) in a greenhouse host range study, raising concerns of this pest being capable of infesting crops and/or native flora of economic or ecological importance. Current recommendations to landscape professionals for managing this pest are limited to applying neonicotinoids as foliar sprays or soil drenches/injections, partly because there is a lack of information on efficacies of pest management products from other insecticide classes. Three landscape trials were conducted, two in Texas and one in Louisiana, during 2016 to evaluate rates and application techniques of two neonicotinoids (imidacloprid and dinotefuran) and several other systemic or contact insecticides including insect growth regulators (IGR) and horticulture oil against CMBS. Results indicated that, in addition to neonicotinoids, insecticides from other chemical classes are also effective and can be incorporated into an IPM program to control CMBS. For example, IGRs such as pyriproxyfen by itself or azadiractin in tank-mix with horticulture oil can provide up to 210 days of control when applied at the time of crawler emergence in the spring, and their efficacies lasted longer than foliar applications of dinotefuran. Therefore, landscape professionals can select products based on pest pressure and/or preference of their customers.