Two weeks ago I wrote about the use of horticultural oils in controlling pests in your yard and garden this summer, but there is one that is deserving of a column of its own and that is neem oil.
If you have searched for the perfect pesticide that is safe and non-toxic for your garden, then neem oil the product for you. Neem offers just about everything a gardener could want with none of the nasty effects that many man made chemical preparations contain.
Neem oil is a pesticide that occurs naturally from seeds in the neem tree or Azadirachta indica. The tree is found in South Asia and India and is common there as an ornamental shade tree.
It has a bitter taste, garlicy smell, and had been used for hundreds of years to control plant diseases and pests but has a variety of other uses as well. The seeds have been used in wax, oil, soap and can also be found in organic cosmetics, toothpaste, and pet shampoos.
Although the oil can be found in most of the tree, the seeds hold the highest concentration. The oil contains a mixture of components with azadirachtin being the most effective for use as a pesticide. Neem can be found in granular form, as a dust, a wettable powder or a concentrate.
It works by acting not only as a repellant but it also has insecticidal properties which interrupt the insects hormonal system making it more difficult for them to lay eggs or grow well. It also interferes with their ability to feed and mate, thereby weakening the population as a whole. As an oil, it works by smothering the insects so that they can’t breathe, causing death.
One of the best things about this pesticide is that it’s very safe to use if applied according to label directions. It has a half life of three to 22 days when used as a drench in soil, but only 45 minutes to 4 days when it is mixed with water. It is virtually non-toxic to birds, bees, and wildlife, making it one of the safest controls you can use in your yard. It works well to control aphids, mealybugs, thrips, whiteflies, scale and most insects with soft bodies.
When mixed with water and applied as a foliar spray, it works just like other horticultural oils do, by smothering the breathing holes of the insects. Since some plants can be affected by neem oil, be sure to mix up a small amount and test on a small area of the plant first. Wait 24 hours and check to be sure there is no damage before applying to the rest of the plant.
Apply neem in the evening or on a cloudy day when there is no direct light to avoid having the foliage burn and to allow time for the oil to seep into the plant. Do not use neem in extreme temperatures, either hot or cold and avoid using it on plants that are already heavily stressed.
Applications on a weekly basis will kill pests and keep things like powdery mildew in check. Apply according to label directions and as you would use other oil based horticultural sprays by having the leaves are completely coated in order to have an effective kill.
In addition, since this product is so safe, but effective, to use, it is considered safe to use around bees although I wouldn’t advise spraying it directly on the bees or their hives. And since it does not target insects that do not chew on leaves, your beneficial insects like butterflies and ladybugs will not be harmed either. However, it is an irony that the aphids that you are trying to kill are the food supply for your ladybugs, so if you use neem and the aphids are killed, then your ladybugs may disappear. Do not assume that the neem killed off the ladybugs as well!
Although the “perfect” insecticide does not exist, neem comes very close. Used by gardeners for centuries, it’s a good choice when looking for something safe to use, while keeping pests under control, but still protecting our environment and our food supply.