Voles and Pocket Gophers in Montana Orchards
Several small vertebrates can cause damage in orchards including voles, pocket gophers, rabits and squirrels. Identifying which species is causing damage and taking proper control measures to protect trees are important to successful control of these animals.
Voles and pocket gophers are the primary rodent pests in Montana orchards. Young trees with small diameter trunks are particularly vulnerable to damage from vole feeding on tree bark. Pocket gophers, which feed mostly on tree roots, can also lead to decline in tree vigor and eventually death as they eat away at the tree's root system when left unmanaged. While ground squirrels can also be a problem in agricultural landscapes, they tend to be less frequent in orchards. The Montana Department of Agriculture Vertebrate Pest Website has several resources for managing voles and pocket gophers including a guide for identifying species accurately titled Vertebrate Pest Identification Key: Field Rodents.
To properly manage both voles and pocket gophers it is important to understand their lifecycle as well to understand their habitat as well as feeding and breeding habits to properly time controls. The Montana Department of Agriculture's guides Control Techniques for Pocket Gophers and Voles in Montana, Their Biology, Damage and Control provide informaiton on the life cycle and management of both pests. Additionally, the Intermountain West Fruit Management Guide includes additional resources on the five components to successful management of rodents in orchards: habitat destruction, removal of food supply, exclusion from trees, facilitation of predators and chemical controls.
Other species including squirrels may strip bark from trees in winter and rabits may feed on limbs of trees particulary during high snow years. For more information on identifying damage from secondary small vertebrate pests visit the University of Saskatchewan's resource Animal Damage to Trees: Nuisance to Damaging.
Left: Pocket gopher mounds near declining trees. Middle: Pocket gopher feeding damage on tree roots resulting in removal of tree. Right: Squirrel damage to young tree (photo: Michael Billingsley).