Organic Orchard Management: Pest Management Concerns
Beneficial insects are an excellent tool in an organic production program but cannot be counted on as a stand-alone method of control. Any pest management program needs to be a multi-faceted plan of action. A well balanced “toolbox” for an organic pest management program may include beneficial insects, bat boxes, insect-specific bacteria or viruses, mating disruption, tangle foot, apple bags, baits, traps, and less toxic organic pesticides.
Vertebrate pests such as mice and voles can become a serious problem in orchards during the winter where surrounding hedgerows, brambles, or fields provide an ideal rodent habitat during the summer months. When snow cover deprives them of other food sources, they tend to gnaw on the lower branches and the crown of trees, which can cause damage or even death. Many species of fruit-eating birds also thrive in hedgerows or woods, and fruit damage by birds in late summer tends to be more problematic where they have an ideal habitat around orchards.
Replanting certain fruit trees into land previously planted with fruit trees often results in stunted trees and reduced yields. This disease syndrome, known as replant disease, has nonspecific causes that often differ from one site to another. Multiple biotic and abiotic factors are involved in replant disease. Organic growers can potentially minimize the negative effects of apple replant disease by avoiding the old tree rows of the previous orchard when planting new trees. Additionally, several rootstock selections are more resistant to replant disease.
Pre-planting cover crops of marigold flowers, certain oilseed rape cultivars, and Sudan grass hybrids, may provide partial control of replant disease in some orchards. Replacing soil from the planting hole with a mixture of fresh soil and compost may also be helpful. Other factors that may alleviate apple replant disease include allowing a fallow period before planting, soil pH adjustment, minimizing soil compaction, improving soil drainage, correcting nutrient deficiencies, and providing supplemental irrigation immediately after nursery trees are planted in the orchard