Ground cover plants and selective insecticides as pest management tools inapple orchards

The quantity and quality of fruit in 2 adjacent apple orchards in eastern W est Virginia were compared between 1 conventionally managed orchard and 1 w ith ground cover plantings underneath apple trees and reduced insecticide a pplications. Four species of plants [dill, Anethum graveolens L.; buckwheat , Fagopyrum esculentum Moench; dwarf sorghum, Sorghum bicolor (L.) Moench; and rape, Brassica napus L.] were planted in alternating, single-species st rips under the tree canopy, and only 1 broad-spectrum insecticide (phosmet) plus Bacillus thuringiensis was applied in the ground cover orchard over t he 2-yr period (1995-1996) of the study. The conventional orchard received 5 applications of an organo-phosphate each year. Disease management was the same for both orchards. The ground cover orchard had significantly greater populations of spirea aphid (Aphis spiraecola Patch) and leafhoppers [Typh locyba pomaria McAtee, Edwarsiana rosae (L.), and Emposaca fabae (Harris)] than the conventional orchard. The conventional orchard had more damage fro m fire blight than the ground cover orchard. Total yield of apples from the ground cover orchard was significantly less than in the conventional orcha rd, probably because of competition by the ground cover plants for water an d nutrients. Fruit quality was lower in the ground cover orchard in 1995 (7 6% undamaged fruit compared with 80% undamaged in the conventional orchard) ,but in 1996 there was no difference in fruit quality between orchards (75% undamaged fruit). Plum curculio, Conotrachelus nenuphar (Herbst),damage wa s significantly different between orchards, but different orchards had grea ter damage in each year. In 1996, fruit in the conventional orchard had mor e apple scab, but in the ground cover orchard fruit had higher levels of su mmer rots and other diseases. In this study, ground covers and reduced inse cticide use were not an acceptable alternative to conventional pest managem ent because of reduced yield. However, with better management of ground cov er plantings to avoid excessive competition with the apple trees, this stra tegy of pest management shows promise for reducing insecticide use in apple orchards.