Submitted to: European Journal of Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 1, 1996
Publication Date: N/A
Interpretive Summary: Reducing the use of pesticides is a major concern of consumers, farmers and regulatory agencies. Replacing chemical pest control with greater biological control is a high priority for American Agriculture. In this paper we evaluate the use of ground cover plants in an apple orchard to enhance biological control of insect pests. Biological control was increased without reduction in yield or an increase in plant disease. Thi is a preliminary report, but it does show that use of ground cover plantings may be used as a pest management tool in apple orchards. These results will be used by agricultural researchers to refine methods to use ground cover plantings to increase biological control of insect pests.
Technical Abstract: Four ground cover species, planted to increase biological control, were found to have minimal effect on productivity in one study with mature apple trees in West Virginia, USA. In a second study, two apple orchards were planted in 1992 to test the effects of diverse ground cover plants on pest management. The conventional orchard was managed according to standard commercial practices and the IPM orchard was planted with Secale cereale and Trifolium pratense. In May 1993, the IPM orchard received a Bacillus thuringiensis spray and the conventional orchard had an application of azinphosmethyl. Fungicide applications were similar for the two orchards. An introduction of branches from an unsprayed orchard into the IPM orchard enhanced biological control of Panonychus ulmi. Adult parasitic hymenoptera were more abundant and diverse in the IPM orchard. Ground covers reduced the vigor of the trees which resulted in much lower aphid populations than in the conventional orchard, thus reducing the number of aphidophagous species. However, the beneficial community had similar diversities in both orchards, indicating a more diverse community of non-aphidophagous predators. The community of phytophagous insects in the IPM orchard was also more diverse than in the conventional orchard, providing a more stable food source for predators. Powdery mildew showed fewer infections in the first year after planting in the IPM orchard; fire blight and apple scab showed no differences between orchards.