Cover Crops in Field-Grown Nurseries: Impacts on Tree Growth, Pest, and Beneficial Arthropods

The purpose of this thesis was to evaluate the performance of cover cropping in ornamental nursery production systems. The first experiment evaluated the growth of red maple trees at two different transplant timings into a crimson clover, Fall Transplant and Spring Transplant. The trees in the Spring Transplanted treatment grew more compared to the Fall Transplanted treatment. In the second experiment, the establishment of two winter cover crops, crimson clover and triticale, was evaluated using Broadcast or Drill planting methods. The triticale established better with Drill method while crimson clover established equally well when Drilled or Broadcast. No significant differences were observed in soil microbial biomass carbon and nitrogen, or arthropod community composition indices between the treatments. The third experiment consisted of the final two years of a four-year study on red maple trees grown with or without cover crop during the first two years post-transplant. The initial two-year study established the success of the cover crop in protecting trees against flatheaded borer damage, but with a negative impact on tree growth. The total number of damaged trees during years 3 and 4 confirms that trees are more susceptible during the first two years after transplant. A total of 24 attacks on Herbicided trees, 2 attacks on Herbicide + insecticide trees, 6 attacks on Cover Crop trees and 0 attacks on Cover Crop + Insecticide trees were recorded. Trees in Herbicide rows remained one season ahead in growth compared to the trees under Cover Crop rows. A fourth experiment was conducted as a follow-up to the original cover crop study. Four treatments were evaluated: Cover Crop, Early Kill Cover Crop, Herbicide and Mulch Mat. The Early Kill treatment was evaluated to minimize competition between the cover crop and trees while still providing protection against borers. Unfortunately, the Early Kill treatment did not prevent borer attacks. Over the two-year evaluation period, the Early Kill treatment had more attacks than the Herbicide treatment (16 vs. 11 attacks). The Cover Crop and Mulch Mat treatments had 6 attacked trees each