A Survey on Ambrosia Beetle (Coleoptera: Curculionidae) Problems in Ornamental and Pecan Industries in Georgia1

Abstract

The ambrosia beetles, mainly Xylosandrus crassiusculus (Motschulsky) (Coleoptera: Curculionidae: Scolytinae), are serious pests of young trees in the ornamental industry and pecan orchards as infested trees develop branch dieback with occasional tree mortality. Surveys were conducted in the ornamental industry in 2020 and 2021 and the pecan industry in 2020 because clientele perspective on the extent of damage, phenology, monitoring, management, and loss related to the ambrosia beetle was unclear. Of 35 and 40 ornamental industry respondents, 68% and 82% indicated problems with this pest in 2020 and 2021, respectively. Of 66 pecan industry respondents, 52% reported beetle problems in 2020. About 85% of ornamental and 58% of pecan respondents indicated that 1–10 trees were attacked by ambrosia beetles and 1–30 or more trees were culled annually. The beetle problem persists throughout the growing season but appears greater during the spring than in other periods. About 73% of respondents indicated that current monitoring tools helped them with management decisions; however, a proportion did not use recommended monitoring tools but instead relied on visual signs to determine attacks on trees. In the 2020 surveys, only 37% of ornamental respondents and 43% of the pecan respondents used insecticide sprays, whereas in the 2021 survey, 71% of the ornamental clientele (mostly nurseries) sprayed pyrethroid insecticides for ambrosia beetle management. In 2020 surveys, about 48% and 56% of ornamental and pecan respondents, respectively, spent <$500 USD for ambrosia beetle management.