Neem

Derived from the neem tree, oil derived from the seeds of this plant kill or repel many insects, though pests are most effected. Rather than kill directly, the limonoids present in this oil, and in particular a compound called azadirachtin, inhibit feeding, maturation and reproduction of insects that ingest this oil. Azadirachtin and other limonoids are biodegradable.

Neem oil or azadiracthin preparations are effective against hundreds of species, including aphids, beet armyworms, bollworms, borers, cabbage worms, caterpillars, Colorado potato beetles, flea beetles, Japanese beetles, June beetles, lace bugs, leafhoppers, mealybugs, mites, sawflies, thrips, tomato hornworms, webworms and weevils, whiteflies, and lawn-killing white grubs. And more - many more! If unsure, Google your pest to see if neem will work.

Neem oil can be effective when used preventatively against fungal diseases including Alternaria, anthracnose, black spot, various blights and early blights, powdery mildew, and rust. It can also be used against harmful nematodes.

Neem is best applied on a cloudy, humid day, or a cooler part of the day; evenings are preferred. Dilute as per manufacturer's instructions, and use fresh. Unmixed, it has a shelf life of up to one year.

Ideally, neem oil should be used either preventatively, or at the first sign of pest activity. It may need to be reapplied every two weeks, or after a heavy rain.

Neem is not as effective against severe pest infestations, and should be used in conjunction with other methods in these situations.

Neem is safe for most plants, birds and mammals, as well as most beneficial insects. Indeed, neem gum is used in some food products, and neem twigs are used to brush teeth.

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