Neem oil is pressed from the seeds of the Azadirachta indica tree. The seeds, leaves and bark of the tree are all used medicinally. This evergreen tree is native to Southeast Asia. It has been grown and used extensively in India for many years. The neem tree ranks high in the United States among trees of interest. Neem oil has been approved by the USDA for pesticide applications. This is a very marketable tree that can be grown and harvested sustainably in warmer regions of the United States.
Neem Oil as a Pesticide
Neem oil can be used as an organic pesticide. As a spray it is effective against leaf-sucking insects such as aphids, thrips, mites, mealy bugs and white flies. It can also be poured into the soil around the base of plants. This will destroy larvae before they mature into beetles or weevils that can eat bark and foliage. It does not cause harm to beneficial insects. The oil is mixed with a surfactant to make it easier to apply. You can buy it as a commercial product in the horticulture section. You can also mix your own pesticide. Add 2 tbsp. of pure neem oil to 1 gallon of warm water. Add 1 tbsp. of dish soap per gallon as a surfactant. Use a horticultural sprayer to apply the oil. Neem oil must be applied when outdoor temperatures are 60 degrees Fahrenheit or above.
Neem as a Fungicide
Neem oil is also effective against a host of fungi that attack plant foliage. Roses are one of the main targets of fungal problems. Neem will work against black spot, powdery mildew and rust. Fungicides must be applied early before the infection has spread. Remove infected leaves from the plant and those on the ground. Spray neem oil using the same concentrations as are used for pesticide applications. Avoid applying oils to plant foliage in hot sun or they can burn. Apply first in early spring, a second application in midsummer and another in the fall.
Neem is undergoing intense research for its use as a medicinal herb. It has been used for years in India by those who practice Ayurvedic medicine. Taken internally as a tea, neem has been known to boost the immune system. The bark also contains a high amount of antioxidants. The oil contains components that are antibacterial and soothing so it is used in liniments for skin eruptions. As with many herbal remedies the body needs time to process the compounds. Using neem excessively can be damaging to the liver. Used moderately, it is a safe botanical medicine. The one known issue is the effect it has on the reproductive organs. Neem should not be used by pregnant woman or it could cause a miscarriage.
Neem oil has a steroid component that has a healing effect on the skin. The oil is used in products aimed at scalp and skin inflammation such as shampoos and soaps. It is safe for pets and can be found in flea and tick shampoos. It is a common ingredient in herbal hand and body lotions. It is good for the skin but is also known to safely repel mosquitoes. Neem oil is also used in toothpaste because it is soothing to the gums. Neem does not smell very good, so it is usually mixed with other herbal ingredients to improve the odor.
Neem as a Contraceptive
Because of neem's effect on the reproductive system it is being studied for use as a contraceptive. There already is strong proof of its effectiveness to prevent pregnancies. Scientific studies have been performed on rats. Some tests proved neem to be 100 percent effective as a contraceptive. Neem is being considered as a possible contraception method for humans.
Growing the Neem Tree
There are Azadirachta indica tree farms in the United States. This tree can be grown in warmer climates with a USDA hardiness zone of 9 and higher. It is a good tree for full sun but will handle partial shade. This is a very drought-tolerant tree. The evergreen foliage is compounded with as many as a dozen leaflets lining the stem. The leaves are dark green and glossy. The small white flowers are sweetly scented. This is a very large tree at maturity. The neem tree is easy to propagate from seeds or from cuttings.