2018 ASHS Annual Conference

Exotic ambrosia beetles have been an important problem in ornamental and fruit tree production for decades. Due to their small size, wide host range and season-long period of activity, chemical control measures can be costly and unreliable. Alternate measures of control are needed to protect tree crops. Field trials were conducted in Mississippi, Virginia, Tennessee, Ohio and South Carolina to determine how well a wrap of deltamethrin-treated net can protect flood-stressed trees from ambrosia beetle attacks. Treatments in 2017 included 1) an unflooded negative control tree with no net, 2) flooded positive control tree with no net, 3) flooded tree with an untreated net and 4) flooded tree with a treated net. In 2018, an additional treatment using a finer mesh size was tested with the aim of achieving greater control. In each year, trees were left along the edge of infested forests for ~1 mo, after which counts of completed and abandoned beetle galleries were made along the length of the tree trunks. In 2017, while attacks were significantly lower on trees with treated net as compared with the other flooded trees, some beetles were able to crawl through the treated netting and complete gallery excavations. However, counts of abandoned galleries were significantly higher on the treated-net trees, representing beetles dying from insecticide exposure before they could complete galleries. New data from 2018 trials will be presented.