There are two primary approaches to biological control: conservation of existing natural enemies and augmentation by making releases of natural enemies. Considerable research has been done on both of these approaches for pest management in commercial orchards. Conservation biological control has been widely utilized and is very important. Augmentation biological control has been shown to be effective in many cases, but often is cost prohibitive. There are a few exceptions.

Those who do research on biological control in commercial orchards are often frustrated that sources for funding such research are few and far between. It should not be too surprising, then, to learn that funding for such research in the home garden is almost nonexistent. Therefore, when asked what commercial biological controls are effective in the home orchard, we have very little data on what works. Also, we have very little data on what does not work. We, therefore, have to extrapolate from research that has been conducted in commercial orchards. Often, such an extrapolation requires a leap of faith because the environments of a home orchard and a commercial orchard are often quite different. What works in one may not work in the other. In some regards, augmentation biological control may be more achievable in the home orchard. One reason is economics.

Home gardeners are often willing to invest heavily in their gardens, both to assure a bountiful and assumingly safe harvest, but also because gardening is often considered recreation and therefore worthy of some additional investment. . With these thoughts (but very little data) in mind, the following are possible options when considering augmentation biological control in the home orchard.

Bacillus thuringiensis is certainly a proven performer. This microbial insecticide is effective against foliage and fruit feeding caterpillars such as cankerworms, tent caterpillars, fall webworms, leafrollers and fruitworms. The residual period of activity after application is very short and multiple applications may be necessary. Sprays should be timed to control young larvae. Bt will not be useful against interior-feeding caterpillars, such as leafminers or codling moth larvae inside of fruit.

Insect parasitic nematodes may provide some benefit against insects that spend some of their life in the soil (such as plum curculio and apple maggot), but there has been little research on such applications in orchards.

Of the commercially available parasites, Trichogramma has the greatest potential. Several species are available; T. platneri is often recommended for use against tree-dwelling pests. Potential targets include codling moth and leafrollers. High release rates are necessary because the tiny parasitic wasps can rapidly disperse from release sites, a problem when trying to cover small areas. Because the egg is the target stage, releases have to be properly timed to be effective.

Green lacewings are generalist predators that will feed on may pests, including aphids, scale crawlers, spider mites and small caterpillars. I recommend applying them as eggs, which are the easiest stage to handle. Two or three releases during the growing season will help control many types of pests.

Spider mites are often not problems in home orchards, but if these are of concern, predatory phytoseiid mites are effective predators. They are rather expensive to use. Check with suppliers for suggested species, release rates and prices. Release should be made shortly after the end of the blossom period. Most of the above suggestions relate to the control of leaf-feeding pests.

Regrettably, there are very few options for biological control of serious fruit-feeding insects, such as codling moth, plum curculio and apple maggot. Some non-chemical methods are used for these pests, such as limb-jarring for plum curculio and trapping of apple maggot. Information, on these methods are available from many extension offices. If it is necessary to use broad spectrum insecticides, remember that these may interfere with the activity of predatory or parasitic insects that have been released into the orchard.

By Dan Mahr University of Wisconsin - Madison/December 1997 from Midwest Biological Control News, April 1997.

Information on our site was developed for conditions in the Northeast. Use in other geographical areas may be inappropriate.

The information in this material is for educational purposes. The recommendations contained are based on the best available knowledge at the time of printing. Any reference to commercial products, trade or brand names is for information only, and no endorsement or approval is intended. The Cooperative Extension system does not guarantee or warrant the standard of any product referenced or imply approval of the product to the exclusion of others which also may be available.All agrochemicals/pesticides listed are registered for suggested uses in accordance with federal and Connecticut state laws and regulations as of the date of printing. If the information does not agree with current labeling, follow the label instructions. The label is the law.Warning! Agrochemicals/pesticides are dangerous. Read and follow all instructions and safety precautions on labels. Carefully handle and store agrochemicals/pesticides in originally labeled containers immediately in a safe manner and place. Contact the Connecticut Department of Environmental Protection for current regulations.The user of this information assumes all risks for personal injury or property damage.Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Kirklyn M. Kerr, Director, Cooperative Extension System, The University of Connecticut, Storrs. The Connecticut Cooperative Extension System offers its programs to persons regardless of race, color, national origin, sex, age or disability and is an equal opportunity employer.