The unique features of Neem oil make it a preferred product among organic gardeners. It controls whitflies, aphids and scale insects, to name a few.
It also controls fungal infections including black spot, rust, mildew and scab.
It can be used indoors or outdoors, on vegetables, trees, shrubs, fruit trees, and nut trees.
Neem oil is manufactured by crushing and extracting oil from the fruit and seeds of the Neem tree (Azadirachta indica). Neem is also used to repel mosquitoes.
It’s not a poison, like pyrethrum which is a toxin produced by chrysanthemums. Instead, Neem oil affects insects in two different ways.
Neem oil has a bitter taste, and many insects do not like to eat it, and using it on plants actually repels many insects.
As an Insecticide
The active ingredient in Neem oil is azadiractin, and it has several different effects on insects. Insects go from egg to larva to pupa to adult. Neem oil actually interrupts the metamorphosis process, inhibiting insects from growing to the adult state.
- It prevents adult insects from developing a hard exoskeleton, which causes dehydration.
- It prevents egg production and sterilizes insects, making it impossible for them to reproduce.
- Neem oil also disrupts insect digestion and excretion.
Interestingly, Neem oil doesn’t affect beneficial insects. In fact, it may even assist some beneficial insects such as honey bees by ridding them of mites, known to be a cause of infection and death among honey bees.
It is non-toxic to humans, birds, earthworms, butterflies, hone bees, lacewings (which are voracious feeders on harmful insects) and other animals. In fact, research is mounting Neem oil may provide significant health benefits to humans.
As a Fungicide
Neem oil does not kill fungus, per se. What it does is coat surfaces infected with fungi and prevents spores from spreading.
Making Neem Oil Spray
Neem oil can be purchased on the open market. There are also a number of companies which process and package Neem oil.
Gardeners who want to make their own Neem oil spray can follow the following directions:
- Slowly mix one ounce of Neem oil to a gallon of warm water.
- Add from one to one and a half teaspoons of dishwashing liquid and mix well.
- Pour the liquid into a chemical sprayer and spray infected areas.
Neem oil will lose its strength in four to eight hours, so only make enough for immediate use. Keep it cool until ready to spray.
Spray the solution on the soil around the roots of plants, and on leaves and stems. Make sure to spray the underside of leaves as well as the tops.
Repeat the process once a week for a month. With severe insect infections, increase the concentration of Neem oil. By spraying around the plant roots, Neem oil will be taken in by the roots and it will become a systemic pesticide.
Robert Dailey - Robert Dailey’s interests and abilities are wide-ranged and eclectic. As a master gardener and garden writer, both his garden and ...
