I’ve been prompted to write an article about neem oil to clarify some issues and offer some perspective on some things that I’ve heard in recent conversations.
First – in the spirit of full disclosure: I sell neem oil. I started using neem oil in my garden about 4 years ago when I was still doing conventional gardening. We kept having outbreaks of spider mites on our cucumbers and tomatoes, and the chemical insecticides just weren’t getting a good kill on them for whatever reason. We heard about neem oil from a retailer and decided to give it a try – we were blown away with the results. The mites died and the larvae stayed gone after just one application. Since that time, neem oil has been the only insecticide I have purchased for my garden or trees.
When I started RoT Organics with my partner, we decided we’d be the only landscape company around that would actually guarantee that we could keep your vegetable garden insect free because we knew neem oil worked well enough that we could warranty our work. Starting around August 20th our primarily business activity will shift to distributing our new EPA approved neem oil product. So…I definitely have a vested interest in this discussion. At the same time, I come by selling neem honest, as the result of using so much of it.
About neem oil – there are many neem oil products on the market, and you have to be very careful what you buy. The ONLY neem oil you should buy for an insecticide is a 100% cold pressed neem oil that is labeled to control bugs – those are the only neem oils which are quality controlled to ensure the amount of pesticidal components.
100% cold pressed neem oil was only registered as a pesticide by the EPA in 2010 – until that point, neem intended for use as a pesticide was separated into two different products. Some manufacturer would take a huge amount of 100% neem oil and then treat it with alcohol and other solvents which would remove all of the Azadirachtin and related substances from the oil, leaving you with the two products: Azadirachtin and Clarified Hydrophobic Extract of Neem Oil. Neither of these products is what you should spray on your garden, because the oil works best as a complete and balanced product, the way the oil naturally evolved.
What you want is 100% cold pressed neem oil – neem oil as it was pressed from the seeds of the neem tree. The process is similar to pressing any oil from seeds, and the oil is not refined any more at this point.
Always, always, always read the ingredients list of a neem product before purchasing – many products will just call themselves “Neem Oil”, but when you look at the ingredients you see the term “clarified hydrophobic extract of neem”, which is absolutely not the same. Clarified hydrophobic extract of neem oil is lacking the major insecticidal chemical of the oil – Azadirachtin.
I only sell and use 100% cold pressed neem oil. The product that I am currently bringing to market has a guaranteed content of 3000 PPM of Azadirachtin, which is the major insecticidal chemical within neem oil. This is a much higher concentration than would normally exist within any one seed; without the patented controlled-pressing method used to make our neem oil, the Azadirachtin content of most neem seeds is around only 10% of our product.
Is neem dangerous to bees , ladybugs, earthworms, or other beneficial insects? How about toxic to people and pets?
No! When applied at the recommended doses and rates, neem oil is not toxic for all non-target insects, plants, and animals.
The epa summary for cold pressed neem oil is available at http://www.epa.gov/oppbppd1/biopesticides/ingredients/factsheets/factsheet_025006.htm#environmentrisk
They conclude “No risk to human health is expected from the use of Cold Pressed Neem Oil because of its low toxicity via all route of exposure. Cold Pressed Neem Oil has been used for hundreds of years to control plant insects and diseases. EPA concluded that Cold Pressed Neem Oil is not a mutagen, and is not a developmental toxicant. Based on the review and analysis of the guideline studies, no additional toxicity data are required to support food uses of this biochemical.”
“The data submitted and reviewed showed that there is no reason to believe that any nontarget organisms, including honeybees and other beneficial insects, would be adversely affected by the use of Cold Pressed Neem Oil.”
But I’ve used neem and seen dead bees the next day?!?
You definitely weren’t using 100% cold pressed neem oil – probably an Azadirachtin based product that called itself neem oil or something similar. Pure Azadirachtin can harm honey bees when sprayed directly on them and has different toxicological data than neem oil. When naturally existing in the chemical balance and ratio that it does in pure neem oil, the levels of Azadirachtin present in an EPA certified neem oil is safe for bees and will only make them leave your plants alone.
Also, sometimes people accidentally make a tank too strong, or perhaps leave a tank sitting around and then spray it out after it has separated – in either of these cases, you could be spraying a dose that is too concentrated. Always follow label directions, always use all of the neem oil you mix, and never increase the dosage beyond what the label directions indicate.
What plants should I use neem oil on?
Basically every plant! Ornamentals, food crops, fruit and nut trees, and more. An important thing to remember is that neem oil shouldn’t be sprayed in direct sunlight as it will burn plants – if you have a particularly fragile or finicky plant, you might want to test spraying a lower branch with the neem solution before applying it to the entire plant to ensure that there is no as-yet undocumented adverse reaction.
I spray neem oil on my entire veg garden every couple of weeks, on my fruit trees once the fruit sets, and on all of my ornamental trees.
What bugs does neem oil control?
You need to refer to the particular product label for this information – many neem oils do not control bugs. A good pesticide labeled neem oil will pretty much handle every bug you encounter and don’t want except for roaches (not because neem doesn’t hurt roaches, it’s just not an effective answer for a variety of practical reasons like the space the roaches inhabit – how can you neem in your walls?). If it sucks or chews on your plant, root, or fruit, neem will probably do a good job controlling it.
Do bugs grow a resistance to neem oil?
No known cases of neem resistance have been reported in nature or the laboratory that I know of. Neem oil is not Azadirachtin – it is genetically easy to develop a resistance to one particular neurochemical. Neem oil has dozens of active chemicals that all work together to affect pest insects – it is very difficult to develop a resistance to an attack from all sides at the same time. It makes sense to me that eventually every kind of pesticide will probably be resisted by something – however, neem oil seems to have minimal chance of becoming resistible when compared to other pesticides due to its complexity.
I’ll be opening a thread in the RoT Organics forum section where I’ll field any questions and keep a running FAQ.