WSU Tree Fruit Comprehensive Tree Fruit Site Subscribe to Fruit Matters

Vertebrates

Management of vertebrate pests in orchards can be challenging and expensive. Mice, voles, gophers and deer cause the most damage in Pacific Northwest tree fruit orchards, costing growers an average of $95 an acre for rodent control, not including the damage to the trees. (See Hidden costs of rodent control, M. Hansen, Good Fruit Grower, 2013). Orchard sites next to pastures or unmanaged land will have more vertebrate pests, and new orchards are especially susceptible to vertebrate pest damage. Orchard sanitation, trapping, fumigants, and baits can be used with varying degrees of success to manage vertebrates. Rodent pests can cause serious damage to young trees not yet established, and can girdle older trees by chewing on the trunks. Girdling can cause a reduction in the tree’s health, disease from entry of pathogens, and death of the tree, depending on the extent of the girdling. Trees that are more than 50% girdled require bridge grafting (reference).
When root systems are damaged, the trees are weakened and produce lower yields. The costs of pest control, replacing trees, and lower fruit yield are all combined in determining a pest control strategy. The concept of economic thresholds is helpful in determining whether a pest should be controlled. To justify the cost of control, pest populations must be large enough to cause significant damage. The economic threshold is defined as the population density (number of pests per unit of area) when control measures are needed to prevent the pest from reaching the economic injury level.
The first steps to take are to identify the pest causing damage, monitor the pests on a regular basis, know the pest level that triggers control, know what control methods are available, and evaluate the benefits and risks of each method.  For more on the use of economic thresholds in pest management read this article, (IPM steps for success, G. McAvoy, Growing Produce, February, 2009).
Tree fruit vertebrate pests of the Pacific Northwest are listed here organized by taxonomic group. Click on the group name to open the text panel. Additional information can by found using the Resource Links in the bottom panel.

Rodents Rabbits Birds Deer Resources Links
Top of Page