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Integrated Pest Management (IPM) in the Vegetable Garden

By Laura Pottorff, Colorado State University Cooperative Extension agent, horticulture and plant pathology

If you would like to try your hand at gardening, vegetables are a good place to start.

Most vegetables are easy to grow, so you reap rewards with a minimum of effort. A plus factor to vegetable gardening in Colorado is the lack of many pest problems. The few pests that occur can be managed easily without the use of synthetic, chemical sprays.

For an easy "environmentally friendly" approach to veggie gardening, just follow these simple steps.

  • Prepare the garden soil by incorporating one-third organic matter (peat moss, compost, or aged manure). Till the organic matter in to a depth of 6 to 8 inches.
  • Choose vegetable varieties that do well in Colorado. Early fruiting tomato varieties, for example, are best for this climate. Look at maturity dates listed on plant labels. It's wise to stick to varieties that mature in 60 to 70 days.
  • Choose resistant varieties. Many vegetables are genetically bred to resist certain pests. Tomatoes are good example. They can be affected by two serious diseases in Colorado: Fusarium wilt and Verticillium wilt. Those tomatoes labeled "VFN" should not be susceptible to these diseases.
  • Locate plants according to their needs. Most veggies need full sun. Rotate vegetable plants from one location to another from year to year. Continuous culture of the same kind of plant in the same location provides an opportunity for disease-causing organisms to build up. It is best to grow the same or closely related plants in the same soil only once in every 3 years. This practice "starves out" most fungi that cause leaf, stem and root diseases. An example of crop rotation follows:

                Year 1 - tomatoes, potatoes, peppers, and eggplant (Solanaceous family).

                Year 2 - cucumbers, pumpkin, squash (Cucurbit family).

                Year 3 - cauliflower, brussels sprouts (Brassica family). You also can come up with

                              other rotation schemes.

  • As plants are growing, check them two or three times a week. Monitor the plants for insects such as aphids, spider mites and tomato horn worms, or diseases such as powdery mildew. If you find pests at an early stage, they are much easier to control.

Pest control practices can take many forms. It is best to use those listed below together.

  • Use a practice called sanitation. This means hand-pulling weeds as you find them, picking the tomato horn worm off the tomato plant or removing a diseased branch or leaves. Be clean.
  • Spray plants with a hard stream of water to control low levels of insects such as aphids or spider mites.
  • Use "biorational" pesticides. These are chemicals of low or least toxicity that have very little environmental impact. These chemicals include soaps (such as Safer's insecticidal soap or a mixture of 3 - 6 tablespoons of Ivory liquid, Dawn or Joy per gallon of water), horticultural oils, or sulfur dusts. Insecticidal soaps are very effective in controlling aphids and other soft-bodied insects. Horticultural oils are effective against many insect and disease pests such as spider mites, aphids and powdery mildew. Sulfur dusts are effective in the control of psyllids (pesky tomato insects), spider mites, as well as many disease problems. Remember, even though these products are "environmentally friendly" and least toxic, they are still pesticides and you must read and follow label directions carefully.
  • Incorporate or encourage natural (biological) controls. Lady bugs naturally feed on aphids and often can consume 100 - 300 aphids per day. Green lacewings are another biological control. They feed on aphids, whiteflies, mites and thrips. Be aware, however, that eradication of pest problems will not occur when using biologicals. It is also very difficult to keep a released biological in the area you want it in. For example, lady bugs may eat a few aphids in your yard and leave in search of more food. It is virtually impossible to keep purchased biologicals in your yard once you release them.

Pest control also can include the use of synthetic pesticides (check label to see if they are indicated for the pest you are treating), or fungicides such as Daconil 2787. However, these products should be used if all else fails. Use only in conjunction with proper plant culture, monitoring for pests and sanitation.

This is the process of Integrated Pest Management (IPM). Pest control is easy when we incorporate a variety of pest management tools. Most importantly, however, we need to change our attitude about "nuking" the bugs. Plants can grow just fine with a low level of insect or disease infestation. If the plant can tolerate low levels of pests, then why shouldn't we?

Photograph courtesy of Judy Sedbrook.

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Date last revised: 01/05/2010