Managing crapemyrtle bark scale infestations in urban landscapes and nurseries
Crapemyrtle bark scale is a serious invasive pest of the beloved and widely planted crapemyrtles. This felt scale species was first detected in Texas, and recently in South Carolina (2019) and Delaware (2020). Its current distribution is restricted to Columbia, SC, but will likely expand due to the ubiquity of crapemyrtles in South Carolina landscapes. When infestation is severe, trunks and branches are covered completely by the white, cottony covers of adult females and immature males. Severe infestation can also reduce growth, delay flowering and result in unsightly honeydew and sooty mold. While degree-day model is still being developed, landscape care professionals and growers can easily diagnose crapemyrtle bark scale infestation based on their appearance and host range that is restricted to crapemyrtles. Suspected infestation should be reported to Clemson University Extension Service and the Department of Plant Industry so that proper identification can be conducted. Landscape care professionals and growers are advised not to purchase or plant infested plants. Infested plants should be pruned or culled, and properly disposed. Insecticides may be applied to the trunks and branches (via sprays of contact insecticides), or to the soil (via drench of systemic insecticides). Studies have reported good to excellent efficacy with soil drench of dinotefuran and imidacloprid, and trunk sprays of bifenthrin, buprofezin, dinotefuran and pyriproxyfen. Soil drench should be applied at the time of bud break, and trunk sprays should be applied during or soon after crawler emergence.
Land-Grant Press by Clemson Extension
Landscape care professionals, arborists, ground managers, nursery growers, extension agents, homeowners
Chong J, Coyle D. Managing Crapemyrtle Bark Scale Infestations in Urban Landscapes and Nurseries. Clemson (SC): Clemson Cooperative Extension, Land-Grant Press by Clemson Extension; 2020. LGP 1044. http://lgpress.clemson.edu/publication/managing-crapemyrtle-bark-scale-infestations-in-urban-landscapes-and-nurseries/.