Pest management benefits of compost mulch in apple orchards

The effect of compost application on weed, fungal, and insect pest management in apple orchards was investigated from 1999 to 2001. Composted poultry manure was applied in June 1999 to half of two small research orchards which had previously received little or no management. The compost provided weed control for 1 year after application. There was no effect of compost on apple scab (Venturia inaequalis) infection. In a laboratory experiment, growth of the brown rot fungus (Monilinia fructicola) was significantly slower on a compost substrate than a sterilized compost substrate. The compost significantly affected arthropod abundance during two years after application, with more predators and fewer herbivores in the compost treated plots. Populations of spotted tentiform leafminer (Phyllonorycter blancardella) and migrating woolly apple aphid (Eriosoma lanigerum) nymphs were reduced in the compost plots. This study showed that the use of compost in an orchard ecosystem is beneficial to management of weed, fungal, and insect pests. The use of compost as a mulch in orchard ecosystems should be encouraged as a sustainable management practice because of a potential to reduce pesticide use.