Botanical Pesticide: Neem Tree Oil and Azadirachtin - August 6, 2003
Jeff Schalau, County Director, Agent, Agriculture & Natural Resources
Arizona Cooperative Extension, Yavapai County
Backyard gardeners are always looking for pesticides that are less toxic or "organic". I recently had a client question about neem products and if it would control fig beetles (the green and yellow beetles that love ripe peaches and other stone fruits). Not having personal familiarity, I embarked on some research. One thing I do know: adult beetles of any species can be tough to control.
Neem pesticide products are extracted from the neem tree (Azadirachta indica). Neem trees are native to India and Burma and are a botanical relative of mahogany. The main active ingredient of neem oil is Azadirachtin. Neem has been used for centuries in India for pest control and some references call it "nature's pharmacy". Neem products are labeled for the control of insects, mites, and fungi. Neem products are sold under many product names and brands. However, neem products are often not readily available at the local garden center and may need to be mail ordered.
Neem manufacturers say that it works as an insecticide in two ways: as a growth regulator and as a feeding deterrent. As a growth regulator, neem products prevent insects from maturing. When immature insects contact certain neem products, either through ingestion or external contact, the molting process of the insect is disrupted. As a feeding deterrent, it simply reduces damage by repelling adult insects.
Neem products are labeled for use on many herb, vegetable, vine, and tree fruit and nut crops. The lists of insects controlled includes many aphids, whiteflies, caterpillars, beetle larvae, fly larvae, leaf miners, weevils, Phylloxera, and squash bugs. Unfortunately, I did not see adult fig beetles on the list (it would certainly control fig beetle larvae). Information on neem insecticides also indicated they usually work best as a preventative rather than as a control measure for management of adult insects. This means applying prior to any outbreak. One product label also included a cautionary warning that neem products could adversely affect honeybees and other beneficial insects.
Some of the neem product names that I came found were Azatin, Neemazad, Ornazin, Neemix, Agroneem, and Aza-direct. The active ingredient was most often Azadirachtin. These products work primarily as insect growth regulators. Different manufacturers also indicated patented extraction processes. One product, Trilogy, listed clarified hydrophobic extract of neem oil as the active ingredient. The Trilogy label indicated it controls aphids, scale, and mites and suppresses whiteflies and thrips. Remember that oil-based products can cause phytotoxicity (plant damage) if applied during periods of high temperatures.
As I indicated, I have little experience with neem products, but they appear very promising for home use. This is especially encouraging since some pesticides are being phased out and many home gardeners are seeking less toxic pest control alternatives. Rose growers may also want to explore neem products. To learn more about neem products, go to the Certis USA web site (www.certisusa.com) or a reputable organic gardening supplier (Harmony Farm Supply or Peaceful Valley Farm Supply).
Remember that any pesticide product should be treated with respect and caution. Just because it is extracted from a plant, does not mean that it is harmless. Always read the product label before purchasing, mixing, applying, and after clean up when using any pesticide.
Naming of companies or products is neither meant to imply endorsement by the author nor criticism of similar companies or products not mentioned.
The University of Arizona Cooperative Extension has publications and information on gardening and pest control. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 ext. 14 or E-mail us at firstname.lastname@example.org and be sure to include your address and phone number. Find past Backyard Gardener columns or submit column ideas at the Backyard Gardener web site: http://ag.arizona.edu/yavapai/anr/hort/byg/.
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Last Updated: July 31, 2003
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