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Managing pests in your garden with IPM

News source/writer: Ken Johnson, 217-243-7424,


URBANA, Ill. – When trying to manage pests in your garden this year consider using integrated pest management (IPM) practices.

"As the saying goes, the only things guaranteed in life are death and taxes, and if you're a gardener you can also include pests in the list of life's guarantees," says University of Illinois Extension educator Ken Johnson. "IPM is an approach to reducing pest and disease populations to an acceptable level using a variety of techniques. There are four types of techniques used with IPM: cultural, physical/mechanical, biological, and chemical."

The idea behind cultural management, Johnson says, is growing and maintaining a healthy plant. A healthy plant is less susceptible to disease and is better able to withstand attacks from pests. This means growing the right plant in the right place at the right time.

"You want to make sure you are planting plants that are appropriate for the site they will be planted in," Johnson explains. "Don't plant something that needs full sun in shade, or that requires acidic soils in alkaline or neutral soils. Placing a plant in the wrong environment can prevent the plant from reaching its full potential and will likely lead to a weak plant that is disease and insect riddled."

In addition to selecting the right site for your plant, Johnson says to make sure it is getting the proper fertilization and enough, but not too much, water. "You can also alter the time of your planting to avoid a particular pest. For example, plant summer squash in early July to avoid squash vine borer, because they have finished laying eggs by then." Additional management techniques used in cultural management include pruning, sanitation, and mulching.

The goal for physical/mechanical management is to physically eliminate pests. This can be done in a variety of different ways, such as hand picking caterpillars or bag worms; pruning out diseased branches, webworms, or galls; pulling or hoeing weeds in flower beds or vegetable gardens; or putting up barriers to prevent pests from getting to your plants, such as bird netting or fencing for rabbits and deer.

In biological management, pests are managed with other living organisms—their natural enemies. Insects like ladybugs will eat small soft-bodied insects like aphids, scale, and mealybugs. Lacewing larvae, sometimes referred to as aphid lions, will feed on aphids, scale, mealybugs, small caterpillars, and occasionally mites. In addition, some tiny parasitic wasps lay eggs inside of aphids and when the eggs hatch, the larvae will eat the aphid. Other parasitic wasps lay eggs on caterpillars such as horn worms.

"You may have seen these in your garden before if you grow tomatoes. Infected caterpillars will have a mass of what looks like eggs on them, but they are actually cocoons," Johnson says. "If you see this, don't get rid of that caterpillar. Eventually the wasps will emerge from the cocoon and will go on to attack more caterpillars." Insects can also be killed by fungus and bacteria. For example, milky spore, a bacterium, can be used to control Japanese beetle larvae.

Chemical techniques round out the IPM practitioner's toolkit. The goal is to manage pest populations by using pesticides, whether they are insecticides, fungicides, or herbicides. "If you are using IPM, chemicals are used as a last resort," Johnson explains. "You want to use the three other techniques – cultural, physical/mechanical, and biological – before reaching for the pesticide bottle. If you do go the pesticide route, you want to try and use the least toxic chemical possible."

Before using any pesticide product, make sure to read the label. "The label will tell you where you can legally use it, what it will control, how much you should use, how often you should use it, and any precautions you need to take while using the product," explains Johnson.