The Online Gardener's Handbook 2010
Chapter 1: Causes of Plant Injury
The Larger Pests

Table of Contents

  1. The Larger Pests
  2. Learn More

The Larger Pests

Mice, Rats and Voles

In winter, mice live under the snow, travelling in and on the soil. They can become a problem when their normal food source is scarce. The damage they cause to bark, roots and lawns is not noticed until spring.

Voles can cause significant damage to young trees and perennials by girdling the lower stem and by feeding on the roots and crowns of perennials. Meadow voles usually feed on grass seeds and herbs but shift to bark in fall and winter.

Management Options

Avoid rodent infestations in home gardens by eliminating sources of food, water or shelter. For example, keep garbage cans, recycling bins, compost boxes and all other sources of food (e.g. bird seed) covered and remove all potential areas near gardens where rodents can build nests (e.g. lumber piles, firewood stacked close to the ground). Keep areas near gardens well mowed, as tall grass provides protection for voles.

Place wire mesh tree guards around young trees, pushing them into the soil to a depth of 5 cm and surround them with stones to prevent digging. Maintain a grass free area around young trees and shrubs, and keep all grass mowed short to prevent the creation of a desirable environment for the animals to live and feed in during the summer and fall.

Taste repellents may be available for domestic use. Animals are repelled by the bitter taste but are not harmed. For a list of repellents and baits allowed under the Cosmetic Pesticide Ban, refer to the Ministry of the Environment website. Brush or spray repellents on bark or on the ground in a protective band around trees (refer to the product label for specific instructions) in late fall before a major snowfall. Temperatures should be above freezing. Apply when the bark is dry and rain is not expected, so that the repellent will dry thoroughly. One treatment properly applied gives protection until spring. Place crushed stones around the base of plants to prevent mice from feeding below the treated bark or on the roots. Severe infestations are rare in a normal urban garden, and are usually only a problem in rural areas.

Moles

Moles are small, plump, short tailed burrowing animals with no visible ears and small, poorly developed eyes. They spend most of their lives underground, burrowing constantly in search of worms, grubs and other soil insects. They can cause serious damage by lifting roots of perennials, bulbs, lawns and strawberry and raspberry patches. The tunnels they create let in air that dries out the roots.

Management Options

Set live traps to catch moles and release them elsewhere. Specially designed mole traps work on trip mechanisms, which the mole pushes as it tunnels through an existing burrow.

Rabbits

In winter when food is scarce, rabbits eat bark, twigs and buds of fruit trees and many ornamental trees and shrubs. When snow surface is frozen, they can reach a considerable height. If completely girdled, trees, shrubs or single branches die. Rabbits can also be a problem in the vegetable garden in the summer. Damage due to rabbits is usually a more serious problem in rural areas.

Management Options

Place tree guards (available at garden supply stores) or chicken wire around individual trees or shrubs. Guards must be tall enough to give protection under highest possible snow conditions. In the summer, vegetables can be covered with chicken wire netting, or a chicken wire fence can be placed around vulnerable areas of the garden. Fences should be sturdy and partially buried, to prevent burrowing underneath it.

Brush or spray repellents on bark of fruit trees, ornamental crabapples and other susceptible woody plants in late fall before a major snowfall. Temperatures must be above freezing. Apply when bark is dry and rain is not expected, so that the repellent can dry thoroughly. One treatment properly applied gives protection until spring. Rabbits, deer and rodents are repelled by the bitter taste but are not harmed. For a list of repellents allowed under the Cosmetic Pesticide Ban, refer to the Ministry of the Environment website.

Skunks

Skunks dig up lawns searching for grubs.

Management Options

Management options to reduce grub populations in lawns will minimize the food supply for skunks. See Chapter 7 for suggestions on how to reduce grub populations in lawns.

Squirrels

Squirrels may strip bark from maples, eat buds off trees and rhododendrons, nibble on cherry, peach, pear and apple fruits, dig up bulbs and plant acorns and black walnuts where they are not wanted.

Management Options

Secure pieces of galvanized wire netting over newly planted bulbs using pegs or rocks.

Nail a 45-50 cm sleeve of aluminum, such as those used on roofs, around the tree trunk to prevent squirrel damage if there are no other trees from which the squirrels can jump. Strips should be at least 2 m tall. One end is nailed down at the corners and the other end is tucked under to hold it in place. Allow enough length for trunk expansion as tree grows and loosen nails periodically so the corners do not become embedded in the bark. Branches hanging lower than 2 m should also be pruned off. The same method can be used to prevent porcupines from climbing a tree to feed on bark.

Woodchucks or Groundhogs

Groundhogs or woodchucks can be found in a variety of habitats: fields, old pastures, fence rows, gardens and backyard hedges. They feed on grasses, clovers and succulent garden plants. They may also damage fruit trees or ornamental trees by gnawing the bark, and ruin root systems by digging burrows.

Management Options

Control must be a neighbourhood activity, to prevent animals entering from adjacent property.
Wire fencing around the garden may help stop groundhogs from digging under. Bury the base to a depth of 15-20 cm and turn it outward in a trench, causing groundhogs and woodchucks to dig on an angle.

Learn More

 


For more information:
Toll Free: 1-877-424-1300
E-mail: ag.info.omafra@ontario.ca
Author: OMAFRA Staff
Creation Date: 04 July 2005
Last Reviewed: 25 June 2010