Investigation of hybrid Freeman maple resistance to Chrysobothris flatheaded borers (Coleoptera: Buprestidae).

This article focuses on comparing physiological and biochemical traits of three flatheaded borer-susceptible red maple (Acer rubrum) cultivars ('Brandywine', 'Sun Valley', and 'October Glory') with a potentially resistant Freeman maple hybrid cultivar ('Autumn Blaze') to understand factors related to borer resistance. Field and container experiments showed that the 'Autumn Blaze' hybrid exhibited faster growth, higher sulfur and nitrogen concentrations, and lower flavonoid and zinc levels in leaf tissues compared to red maples, and it experienced significantly fewer flatheaded appletree borer (Chrysobothris femorata) attacks over two years. Herbicide treatment with pelargonic acid (Scythe) affected physiological traits such as chlorophyll content and flavonoid levels but did not increase borer attacks in the field. The study suggests that growth rate, nutrient composition, and secondary metabolite profiles may contribute to the hybrid’s resistance, though further research—particularly on bark tissue and sap flow—is needed to clarify the mechanisms underlying borer resistance.