NEEM IN ORGANIC GARDENING

Neem is approved by the EPA for use on all food crops. State regulations vary, so check with your own state officials concerning the use of neem in organic gardening. Here in Florida, neem use is allowed for organic gardening purposes, but records must be kept on the amounts used and the insect species to be targeted. Dates and time of use need to be recorded as well.

Neem is best applied in the late afternoon for several reasons. Oil-based sprays can be toxic to leaves if they are sprayed under full sun conditions. Neem is usually not harmful to beneficial insects, but direct applications of the spray to the beneficials may cause them problems. It is best not to spray if these are present, and late afternoon works best here. Neem oil itself can deteriorate with exposure to sunlight, so late afternoon spraying allows the neem oil to be absorbed by the plant (and any insects present) without interference from UV rays.

Neem oil spray, as described in the AGRICULTURAL USES section, is also a good treatment for insects and diseases which live in the soil. The ground around the plants should be saturated with the spray, which has two purposes. This will repel insects, as well as cause the kinds of developmental problems commonly found in insects exposed to neem. This will also allow the plants to absorb some neem through their root systems, which will result in a systemic effect. Insects audacious enough to still eat these plants will ingest the neem as well. Internal neem is not susceptible to the same UV degradation as the externally applied spray.

If you are concerned with neem getting into the groundwater, you need not be. Neem is nontoxic and biodegradable. Neem will not harm earthworms. In fact, studies show that earthworms in neem-treated soil were 25% fatter than their counterparts in neem-free soil.

Neem is antifungal, and experiments show neem to be effective against the common disease powdery mildew. In this case neem works best as a preventative. Once this disease has spread neem will not be as effective.

In India and Southeast Asia, neem cake, the residue which remains after expelling the oil from the kernels, is applied to the rice paddies and vegetable gardens. Neem seed cake adds nutrients to the soil while repelling and eliminating insect pests. Neem seed cake and other parts of the tree are used for agriculture in areas where the trees grow, but shipping costs make them an expensive proposition for use in the United States. Neem plantations in Bermuda, Haiti, and Mexico may result in greater availability in the near future. Neem trees will only survive in states with a tropical climate. Some trees are being grown in Florida, but neem grows best in an arid climate. Arizona and Nevada would offer a more hospitable climate.

Please check back for more updates. Feel free to email me if you have any questions or comments.