Insect and Mite Control on Woody Ornamentals and Herbaceous Perennials

Bulletin 504

Insect and Mite Management Alternatives

The Control Options

Cultural Controls

The cultural control option should be our first consideration as an alternative in landscape tree and shrub IPM. Cultural controls in field crops have generally included sanitation, crop rotation, tillage, host plant resistance/tolerance, mechanical/physical destruction and quarantine. If we look at these techniques, we may wonder how these relate to ornamentals in nurseries or landscapes. Though we use different terms, these techniques are commonly used and need to be emphasized more.

1. Sanitation helps remove inoculum or hiding areas of pests. Pruning, raking of leaves and destruction of heavily infested plant stock are sanitation techniques useful on our urban landscapes and nurseries.
2. Crop Rotation is generally used in field crops (ie. corn rotated with soybean) but should be considered for ornamental tree and shrub production. Many nurserymen rotate growing areas by planting different types of stock after a rotation. This seems to help reduce attacks by borers and root infesting diseases. We also need to realize that most trees and shrubs in urban landscapes are limited by space which reduces their vigor with time. Therefore, if a plant has begun to reach its limitations, it should be replaced with a smaller, better suited one.
3. Tillage in field crops exposes resting pests and breaks up the soil for better air and water movement. In ornamental trees and shrubs, aeration and mulching are analogous.
4. Host Resistance uses plants which are less susceptible to pest attack (tolerance) or produce actual toxins (antibiosis) which kill or stop pest growth. Examples of trees and shrubs are well known though poorly utilized. In fact, most insects and diseases which are currently problems can be permanently eliminated with the use of resistant plants. For people concerned with the use of pesticides this is a major option to be considered.
5. Mechanical/Physical techniques are as simple as crushing the pest under foot to using large industrial vacuum sweepers to suck up pests. In our landscape settings, we need to constantly remind ourselves that simple pruning or crushing of pests is preferable to chemical spraying. We are all guilty of spraying an entire juniper hedge for bagworms when only three or four bags were seen which could have been easily picked off and crushed. Likewise, we tend to "Rambo" spray tent caterpillars in the spring when we could just reach in, roll up the nest with the caterpillars inside and dispose of the mess in a bag.
6. Quarantine is a legal method of restricting movement of contaminated plant material. Unfortunately, this technique is rarely effective even though we know that most pest problems arrive on infested plant material. Therefore, we should pay special attention to new plantings which may have pests and plant stresses developed from the transplanting process.
7. Good Horticulture is one of the simple but commonly ignored methods of pest management. In other words, a "healthy" plant can generally fend for itself against insects, mites and diseases. Therefore, one of the most important control alternatives that we can use is tending to the proper needs of landscape plants. We need to match the correct trees and shrubs to the typical alkaline, hardpan clay soils of our landscapes. To not do so causes plant stress which allows pests to gain the upper hand.

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