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Integrated Pest Management (IPM): Garden Insect and Disease Control

Robert Mugaas
University of Minnesota Extension Educator, Environmental Horticulture

Over the past couple of decades there has been ever-increasing scrutiny of the products utilized for controlling pests in our home yards and gardens. That scrutiny is largely based on our growing safety concerns regarding those products, especially pesticides, to adversely impact human, animal and environmental health. In addition, there is increasing disappointment among homeowners and professionals alike with the overuse, misuse and indiscriminate use of pesticides in our environment. It is in this light that new approaches and new strategies are being considered and implemented for managing and controlling pests in our yards and gardens. Enter, Integrated Pest Management (IPM).

IPM described

Integrated pest management is a much more ecologically based approach to pest control. The basic premise of IPM is to minimize populations of pests rather than implementing practices attempting to completely “eradicate” a particular pest. History would tell us that many times these efforts are futile. A continually expanding body of scientific evidence would also suggest that the eradicative pest control philosophy – which only uses broad spectrum, persistent pesticides – is technologically unsound. Where plant insect pests and diseases are concerned, the practice of IPM seeks to regulate their numbers to “tolerable” levels. That is, the degree of pest infestation is kept to a level below that is considered to be a serious health threat to the plant. A healthy garden or landscape plant can tolerate even moderate levels of pest infestation without having its overall health compromised. IPM is based on a common sense approach to pest control as well as employing socially responsible courses of action. However, it is important to remember that IPM does not categorically reject the use of traditional pesticides. Rather, their use is considered only when used for emergency measures such as when natural factors and other pest suppression efforts fail to keep pest populations below economic or damage thresholds. In IPM terms, this is called the “treat-only-when-necessary” approach. The term pesticide is applied to all chemical or biological products designed to “kill a pest.” These include products for killing weeds (herbicides), insects (insecticides), diseases (fungicides) and rodents (rodenticides). In an IPM program, pesticides are carefully selected and applied for specific and selective action on the pest and for minimal disturbance to beneficial species, and of course to humans, wildlife and the environment. Remember, doing nothing can be a valid IPM alternative. In general, IPM rejects the notion of routine application of broad-spectrum pesticides while embracing the use more natural pest mortality factors such as parasites, predators and diseases. In addition, IPM can include human-developed methods for controlling pests through better yard and garden planning, using resistant plant varieties, crop rotation, various cultural practices and reducing the amount of insect or disease pressure by sanitation or trapping. IPM is very practical and can be adopted by anyone, even those casually interested in gardening. It can also be cost effective, environmentally responsible and intellectually appealing. Below are some general cultural practices that can easily be integrated into a home IPM program, followed by a brief list of some “organic” pest control products that are more commonly available from local garden centers.

Cultural practices common to IPM

  • Whenever possible, buy pest resistant varieties of plants. Traditional plant breeding methods have greatly increased the number of plants available resistant to diseases and even some insects.
  • Select only plants well adapted to the particular site where they will be planted as well as to general climate zone here in the Twin Cities. We are considered Plant Hardiness Zone 4. Poorly adapted plants or plants planted in the wrong site conditions are usually more difficult to keep healthy and vigorous.
  • When possible water vegetable and flower plantings at ground level with a hand held watering device or using a slow trickle from the nozzle or specially designed trickle type of soaker hose. This will help keep the foliage dry and is more conservative of water. If using an overhead sprinkler, water early in the day such that the foliage will have a chance to dry off before evening.
  • Thoroughly inspect plants on a regular basis; especially check the undersides of leaves. Deal with any developing problems before they get out of hand.
  • Finally, use organic mulches around your plants to help conserve soil moisture, moderate soil temperatures and provide weed control. Some commonly available organic mulches include compost, shredded leaves, clean hay or straw, shredded wood and wood chips.

Naturally based pesticides

If the occasion arises where you do need to provide some insect or disease control, here are some organic products that can be used. Most are readily available at garden centers under a variety of trade names.

Product and Activity:

  • Bacillus thuringiensis (BT): Bacteria for controlling caterpillars of butterflies and moths.
  • Copper based materials: Some fungicide and insecticide activity.
  • Diatomaceous earth: Treatment primarily for garden slugs.
  • Horticultural oils: Fungicide and insecticide activity.
  • Insecticidal soaps: Mostly insecticide activity.
  • Liquid formulations of lime-sulfur: Fungicide and insecticide activity.
  • Neem products (Azadirachtin): Fungicide and insecticide activity.
  • Pyrethrum (Pyrethrin): Insecticide.
  • Sulfur: Fungicide and insecticide activity.

– From “Lawn and Garden Care the Natural Way”, Lake Michigan Federation

Non-Toxic Pesticide Recipes

Pesticides are chemicals designed to kill insects, rodents and weeds. However, they can also be poisonous to humans, pets and wildlife.

Prevention:

  • Ants: Place dried, crumbled bay leaves in doorways and windowsills. Washing counter tops with vinegar and water is also effective in preventing ants.
  • Caterpillars: Use “stickum” made from 1 1/2 cups rosin (available from athletic supply stores), 1 cup linseed oil and 1 tablespoon melted paraffin. Mix together and put around the trunk of your trees or plant bases.
  • Cutworms: Apply mixed molasses and cornmeal near the base of each plant.
  • Aphids: Cut up 3 pounds of rhubarb or elder leaves. Boil half an hour in 3 quarts of water, strain and cool. Dissolve 1-ounce soap in one quart of water. Mix the two solutions and spray.

Other Non-toxic Insect Sprays:

  • Hot Peppers: Boil 2 or 3 very hot peppers, half an onion and one clove garlic in water. Steep for 5-10 hours and drain through cloth. Spray on foliage. Avoid contact with eyes.
  • Soap: The least toxic chemical for many gardeners is a soap mixture. Spraying plants with soap water will control aphids, mealy bugs, thrips, red spider mites, and lice. Mix two tablespoons of liquid soap per one quart water. Spray on plants. WARNING: Using pure soap, additives or detergents may damage plants.
  • Tobacco Water: Place a large handful of tobacco into four quarts of warm water. Let stand for 24 hours. Dilute and apply with a spray bottle. WARNING: This tobacco spray is poisonous to humans: use caution when handling.
  • Garlic: Mix four quarts water, two tablespoons garlic juice (do not use garlic powder, it will burn plants), 32 grams of diatomaceous earth [available at your local garden store. Please follow manufacturer’s instructions carefully and ask for assistance if you are not familiar with this product], and one teaspoon or rubbing alcohol.

Companion Planting:

Certain pests dislike certain plants; use this to your advantage. By strategically planting your garden, you may avoid pest problems from ever occurring.

  • Plant your beans near potatoes and you’ll repel both potato beetles and bean beetles.
  • Plant chives near roses and you will chase away harmful aphids.
  • Plant marigolds, chrysanthemums, chives, onions, garlic, basil, savory, horseradish, mint, and thyme near your plants. The natural odors and root secretions repel some insects.
  • Plant soybeans near corn to trap chinch bugs.
  • Plant asparagus, marigolds or borage near tomatoes to repel tomato worms. Dill also lures them away from tomatoes.
  • Plant tansy to repel cucumber beetles.
  • Plant radishes to lure maggots away from sprouting corn and cabbage.
  • Plant onions around your beans to repel ants.
  • Scatter your onions throughout the garden instead of planting them in rows. This will discourage slow-moving root maggots that take advantage of onions planted next to each other.
  • Plant onion “sets” not seeds to control onion flies.
  • Plant catnip around the edge of the garden to repel flea beetles.
  • “Mole plant” herbs placed sporadically through your garden discourage moles and mice.
Integrated Pest Management

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