Mechanical Control Methods

Many gardening practices can be included in mechanical control such as the use of barriers or hand picking insects. Mechanical control methods usually are more practical for a small garden than for a large one. They can be used singly or in combination to obtain desired results.

Preventive devices and barriers are often are easy to use, although their effectiveness varies. Such devices include:

• Paper or plastic collars around the stems of plants to prevent cutworm damage
• Cheesecloth or plastic screen coverings for hot beds and cold frames to exclude flying insects
• Mesh covers for small fruit trees, berry bushes, tomatoes and other plants to keep out large insects and birds
• Sticky barriers on the trunks of trees and woody shrubs to prevent damage by crawling insects
• Aluminum foil on the soil under plants to repel aphids

Handpicking of insects and insect egg masses insures quick and positive control. This method is especially effective with foliage-feeding insects such as tomato hornworms, potato beetles, and squash bugs.

Gardeners can use a stream of high pressure water to dislodge insects from plant stems and leaves or even kill them directly. Aphids and soft-bodied insects are likely to be damaged directly by the water stream but many are also dislodged and do not find their way back to the plant. Spider mites can also be washed from leaves with streams of high pressure water. However, sometimes the mites may survive and start colonies on adjacent plants. Water also increases humidity around the leaves which may help to bring spider mite infectations under control. Care should be taken to use water pressure only on sturdy plants to avoid plant damage.

Various types of traps are reportedly successful in reducing garden insect numbers. For example:

• Earwigs can be trapped in rolled up newspapers placed in the garden or other locations where these insects gather.
• Slugs and pillbugs can be trapped under boards placed on the ground. Squash bugs may also congregate under boards in the winter.
• A small pan placed flush with the soil and filled with stale beer will attract and kill slugs and snails.
• A container, half-filled with a 10 percent solution of molasses and water will attract and trap grasshoppers and certain beetles. A banana or other fruit can be added to this mixture to improve the attraction.
• Blacklight traps are general insect attracting devices. Studies have shown that the electrocution devices kill more beneficial insects than pests. Therefore, the use of these devices should be avoided.

Resistant Plant Varieties | Cultural Controls | Mechanical Control Methods

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