Phytochemical changes in maples induced by overspray from two commonly applied herbicides and resulting effects on Chrysobothris sp. preference

Red maple (Acer rubrum) is one of the most popular ornamental trees in the United States. When grown in nursery production, weeds form around the trunks of the maples and compete with the trees for resources. Herbicide sprays are used to manage weedy pests and promote maple growth. Growers take precautions such as spray guards to help prevent chemical herbicides from hitting maple trunks, but there is often some overspray. The stress herbicides cause on red maples can weaken defenses and increase susceptibility of trees to insect pests, including wood-boring beetles in the Chrysobothris genus. The exact mechanism of increased attraction of herbicide damaged nursery trees is unknown. However, previous research has found a direct relationship between herbicide stress and Chrysobothris attraction to the stressed trees. This study focuses on analyzing the phytochemical changes caused by herbicide application and the interactive effects between herbicides and red maple cultivars that may influence Chrysobothris preference. Susceptible cultivars had reduced tannin defenses and increased sugar concentrations.