Cover Crop Usage for Pest Management in Red Maple Tree Production Systems

The flatheaded appletree borer (Chrysobothris femorata Olivier) (FHAB), as well as soil-borne pathogens Phytophthora nicotianae Breda de Haan, and Rhizoctonia solani J.G. Kühn, are serious pests of red maple (Acer rubrum L.) throughout the United States. The goal of this project was to evaluate the effectiveness of cover crops for management of these pests in nursery production. The cover crop was used to camouflage FHAB oviposition sites and with the hope the cover crop would improve soil health and microclimate to combat soil-borne pathogens. Crimson clover (Trifolium incarnatum L.) and winter wheat (Triticum aestivum L.) were sown before tree transplant in 2015. Four treatments (no insecticide + herbicide, insecticide + herbicide, cover crop + insecticide, and cover crop only) were replicated four times in a randomized complete block design with 25 trees per block. All trees from each treatment were evaluated for damage by FHAB, including height of attacks and cardinal direction. Damage by secondary maple pests was evaluated to determine whether the cover crop treatment had any effect. Soils from all plots were sampled while cover crops were growing and post-season, following incorporation into the soil and greenhouse bioassays were conducted in field soils using maple seeds. Field soils were amended with P. nicotianae or R. solani inoculum and non-inoculated pots served as controls. Stand and vigor data of maple seedlings were recorded 4 mo after seeding. Pseudomonads population densities were determined using selective media. Cover crop presence was effective at controlling FHAB damage with results similar to imidacloprid treatments. Better tree growth in the herbicided plots made trees more attractive to other foliar feeding maple insects. Cover crops incorporation into soil reduced disease incidence, especially by R. solani. Maple seedling germination also improved in cover crop incorporated soils. However, the cover crop competed for nutrients, water, and space, thereby decreasing growth of the trees. Cover crops can provide nursery growers with quantifiable protection against outbreaks of insect pests and soilborne diseases, but more work is needed to maximize tree growth