Ground cover plants and selective insecticides as pest management tools in apple orchards

The quantity and quality of fruit in 2 adjacent apple orchards in eastern West Virginia were compared between 1 conventionally managed orchard and 1 with ground cover plantings underneath apple trees and reduced insecticide applications. 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 strips under the tree canopy, and only 1 broad-spectrum insecticide (phosmet) plus Bacillus thuringiensis was applied in the ground cover orchard over the 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 [Typhlocyba pomaria McAtee, Edwarsiana rosae (L.), and Emposaca fabae (Harris)] than the conventional orchard. The conventional orchard had more damage from fire blight than the ground cover orchard. Total yield of apples from the ground cover orchard was significantly less than in the conventional orchard, probably because of competition by the ground cover plants for water and nutrients. Fruit quality was lower in the ground cover orchard in 1995 (76% 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 was significantly different between orchards, but different orchards had greater damage in each year. In 1996, fruit in the conventional orchard had more apple scab, but in the ground cover orchard fruit had higher levels of summer rots and other diseases. In this study, ground covers and reduced insecticide use were not an acceptable alternative to conventional pest management because of reduced yield. However, with better management of ground cover plantings to avoid excessive competition with the apple trees, this strategy of pest management shows promise for reducing insecticide use in apple orchards.