Neem oil is a botanical fungicide, insecticide and miticide treatment made from the seeds of the neem tree.  These trees are native to India and Burma and are related to mahogany.  It is also biodegradable.

Neem works best on early stages of insects by inhibiting their metamorphosis.  It is recommended that this spray be used early in the season and repeated through-out the summer.  Neem also helps reduce soft bodied insects such as aphids, whiteflies and mites by suffocation.

Neem is an organic pesticide that has shown no resistance or immunity to insects as long as it has been in use.

As a fungicide Neem is used as a preventative.  It has the most success when used early in the growing cycle or at the very beginning of diseased symptoms.  It is effective against rot, mildew, rust, leafspot, blight and scab.