2: Investigation of common management practices in pecan (Carya illinoinensis) orchards against ambrosia beetles (Scolytinae)

Georgia is the top producer of pecans in the United States. Ambrosia beetles are a pest of pecans. These beetles often target younger trees that are exposed to stressful conditions such as drought or flooding. Other than spraying insecticides, there is limited management options against these beetles in pecans. Growers employ several cultural practices in younger orchards which anecdotally worked on decreasing ambrosia beetle attacks. However, there is no research-based evidence on whether these tactics are effective on ambrosia beetles. In this study, we deployed 20 ethanol-baited log traps (~6.4cm dia) that were subjected to four different management practices: 1) logs painted with white latex paint, 2) logs sprayed with insecticide at the time of painting, 3) logs sprayed with insecticide every seven days, 4) logs covered with a tree guard, and 5) a non-treated control log. Each treatment was replicated 3-4x and traps were deployed 30-m apart along the edge of a woodlot adjacent to an orchard. Logs were checked for holes and toothpicks weekly for four weeks. Experiments were done in Spring 2020 at two sites in south GA. Our results showed consistently that pyrethroid-sprayed logs, either mixed with paint or spraying every 7 days, incurred the least attacks. Logs covered in tree protectors were attacked at the same rate as the non-treated control. Painted logs had low or moderate efficacy in preventing attacks compared to other treatments. These findings imply variable effectiveness of currently available options for growers although additional studies are needed to validate results.