IPM: A Common Sense Approach to Managing Pests

Home & Commercial Gardening Page | Horticulture & Gardening Home Page
Agriculture, Natural Resources, & Community Development Home Page

John W. Jett

WVU Extension Service

Extension Specialist - Horticulture
This article appeared in the Farm Bureau News, WVU Update, May 2000

Integrated pest management (IPM) represents a holistic approach to pest control promotes good management and stewardship strategies. It involves understanding and observing many factors and their interrelationships as they influence plant growth. These include soil, water, air, nutrients, insects, diseases, landscape design, weeds, animals, beneficial organisms, weather, and cultural practices.

The goal is to manage problems at acceptable levels rather than attempting to eliminate them. In many cases, pest problems can be prevented by selecting the proper plants and providing the best possible growing conditions. Regular observation of the plants in your landscape or garden is critical to help you decide if a problem requires corrective action. Plant problems may occur after a plant has been weakened by other factors, including poor site characteristics, cultural practices, or environmental and nutritional problems.

Before you can recognize or prevent problems, you need to become familiar with the plants, their growth habits, and the conditions necessary for good growth. Here are some suggestions that may help you achieve that goal.

• Make a plan of your existing landscape or garden. Identify the location of your plants and trees.
• Note which plants look healthy and those that have problems
• Know what your plants should look like.
• Be willing to remove plants with chronic problems. For example, azaleas grown in full sun often have severe lacebug problems.
• Replace problem plants with plants adapted to your area. Check gardening references and reputable local nurseries and greenhouses for ideas.

Healthy soils lead to healthy plants. Here are some soil-building tips.

• Incorporate organic matter like compost or manures in flower and vegetable beds regularly.
• Perform a soil test every three years and adjust the pH accordingly.
• Fertilize as needed to maintain vigor.
• Avoid overfertilizing the soil, which can make plants more susceptible to pest problems.
• Establish deep soil beds for better rooting

IPM is not a strictly organic approach to pest control. When necessary, chemicals are applied; however, broad-spectrum pesticides are not the primary management strategy. Residual pesticides remain effective in the environment for days, weeks, or months, which impacts beneficial organisms and pests. In all cases, the least-toxic solutions--physical, mechanical, biological controls--should be tried first. The impact of gardening and pest management decisions often extends far beyond your property lines.

Concern for the environment, development of pesticide resistance, problems with pesticide safety, and the effects of pesticides on nontarget organisms have sparked interest in finding alternative means of controlling pests. One approach is to identify, establish, and conserve beneficial organisms. Beneficial organisms can be grouped into three categories--predators, parasites and pathogens.

Predators attack and consume pests directly. They are usually larger and more active than their prey. For example, insect predators tend to move rapidly and have large eyes and forward-pointing mouthparts.

Parasites use pests as food sources for their young. For example, insect parasites lay their eggs in, on, or near the pest insect. The offspring then grow in or on the host, and eventually kill it.

Pathogens are disease-causing organisms such as bacteria, viruses, and fungi that can infect, kill, or debilitate insects and mites.

Predatory and parasitic insects are often collectively referred to as beneficial insects or "beneficials." It is important to remember that many other beneficial organisms such as fungi, bacteria and earthworms also exist in your yard.

Some of the Common Insect Predators and Parasites Include:

Ladybird beetles (ladybugs, lady beetles) are predators of aphids, mealybugs, and other small insects. Adults vary in size from 1/8 to 3/8 inch. These can be purchased, or they will come into your garden or landscape on their own, as long as residual insecticides are not sprayed.

Lacewings are predators of aphids and other small insects. Adults are ½ to3 -inch long, green or brown, with small heads and large eyes. The wings are longer than the body, are transparent, and have a fine network of veins.

Syrphid or flower files are aphid predators. Adults are 1/8 to 5/8 inch long. They resemble bees with yellow-black or white-black striped abdomens.

Attracting and Conserving Beneficial Organisms

To conserve and protect beneficial organisms in your garden or landscape, provide water, food, cover, nesting places, and a diversity of flowering plants. Reduce or eliminate pesticide use or switch to careful timing of biorational, nonresidual pesticides such as insecticidal soaps, horticultural oils, and Bacillus thuringiensis (Bt) products. Soaps, oils, and botanical pesticides have short-term effects on populations of beneficials compared to typical synthetic pesticides.

In addition, try to maintain a diverse habitat. Provide pollen and nectar sources for adult beneficials by growing a wide variety of annual and perennial flowers so that some plants are blooming throughout the growing season. Check the box below for some good choices.

Provide water by misting or wetting down plants and mulch. This also cools the area during hot weather. Leave shallow, open containers or basins of fresh water on the ground in the shade for birds, toads, frogs, turtles, snakes, spiders, and insects. A diverse habitat of trees, shrubs, and other plants provides shelter, hiding places, and overwintering sites. Straw mulch is especially attractive to spiders.

Here are some commonsense nonchemical control strategies for plant pests.

• Learn to tolerate some damage: Most healthy herbaceous and woody plants can tolerate 20% to 30% leaf defoliation without suffering long-term damage or yield reduction.
• Wait for the "good guys": Aphid feeding in the spring alarms many gardeners. Natural predators and parasites usually clean up local infestations in a month.
• Remove plant or plant parts: The simple disposal of badly damaged plants may minimize the problem on adjacent plants and prevent recurrence.
• Timing of seeding and planting is important. Some pests can be circumvented by growing vulnerable plants when damage is least likely. For example, late-summer squash crops are less troubled by squash vine borer. This requires knowledge of pest life cycles.

Observation and Diagnosis

While monitoring plants for pest problems, you should look at the area surrounding the problem plant. Consider factors such as exposure to elements, proximity to roads or buildings, lighting conditions, and drainage. Look for physical evidence of a problem such as injury, changes in site conditions, soil compaction, construction injury, lawnmower injury, insects, and diseases. Examine all parts of the plant including roots, shoots, trunk, and leaf undersides. Use a hand lens if necessary. Look for a pattern to the injury.

The ability to accurately diagnose a wide range of plant problems is developed over time by patient observation and consulting reliable reference materials. Timely diagnosis of plant problems can help you keep your garden and landscape beautiful and productive. It can also prevent expensive removal and replacement of damaged plants.

For additional information or names of suppliers for beneficial organisms, contact your county's WVU Extension agent.