Ambrosia Beetles and Phytophthora cinnamomi Management Using Plant Defense Elicitors Under Flood Stress Condition

View the project report

Commodities

• Additional Plants: ornamentals, trees, nursery

Practices

• Pest Management: cultural control, physical control

Ambrosia beetles (Xylosandrus spp.), wood-boring insects, and Phytophthora cinnamomi, a soilborne pathogen, are economically important and destructive issues in nursery trees. Like biotic stresses, abiotic stress also contributes to the declining health of nursery crops. Plants stressed with abiotic stress factors such as flooding, drought, and freezing have a decreased host defense mechanism and experience increased susceptibility to different diseases and pests. Flooding has become a problem in Tennessee and increasing flooding events are contributing to the increased attacks by the ambrosia beetles and Phytophthora cinnamomi. Flooded trees are susceptible to both ambrosia beetles and P. cinnamomi. Ethanol is a primary ambrosia beetle attractant; thus, stressed trees releasing it are more prone to attack and colonization by ambrosia beetles. Current chemical control measures are mostly inconsistent and variable and have negative consequences on the environment. Moreover, flood stress can affect insecticide efficacy since insecticide was ineffective at preventing ambrosia beetle attacks when container substrate moisture levels exceeded 50%. This necessitated the need for alternative sustainable management strategies. The specific objective is to explore the role of flooding and P. cinnamomi in predisposing trees to ambrosia beetle attacks and to test the effectiveness of plant defense elicitors Acibenzolar-S-methyl (ASM) (Actigard), and ASM + chlorothalonil (Daconil Action) for the control of P. cinnamomi and ambrosia beetles in container-grown flowering dogwoods exposed to flood stress conditions.

Objective 1. To understand the role of abiotic and biotic stressors in predisposing trees to ambrosia beetle attacks

The purpose of this objective is to assess the role of simulated flood and Phytophthora root rot caused by P. cinnamomi in predisposing flowering dogwood trees to ambrosia beetle attacks. This information will be helpful to growers to prepare for taking necessary management tactics.

Objective 2. To evaluate plant defense elicitors (i) acibenzolar-S-methyl (Actigard), and (ii) acibenzolar-S-methyl + chlorothalonil (Daconil Action) for controlling Phytophthora root rot and ambrosia beetles

The purpose of this objective is to find effective plant defense elicitors for the control of ambrosia beetles and P. cinnamomi in flowering dogwoods under simulated flood stress conditions.