Neem oil for plants is an excellent natural insecticide, ecological, and substantially non-toxic for humans, which does not even disturb bees and pollinating insects in general. For these reasons, it is particularly interesting among the various natural insecticides.
Azadirachtin is the active ingredient found in the seeds and therefore in the neem oil, it is also extracted to produce insecticides allowed in organic farming. To defend the vegetable garden and orchard you can find the products on the market, but also directly use the more natural and less expensive pure neem oil.
By diluting the pure oil in water and spraying it, it is possible to defend against various types of insects such as aphids, altica, Colorado potato beetle, thrips, and Lepidoptera. Neem also has other values in addition to its use in agriculture: it is used in cosmetics and for ecological house cleaning.
The neem tree
Neem or nim (Azadirachta indica) is an evergreen tree native to India and Burma, this large plant produces beautiful white flowers and then an olive-like fruit. Due to its many properties, it is known in its areas of origin as a holy tree or even “village pharmacy”.
This plant has many positive properties and possible applications, among others neem also excellent insecticidal properties, as well as not being toxic to humans and for this reason, it is an ideal pesticide to be used in organic horticulture and orchards.
Neem waste can also be used in natural fertilization, so you can also find neem-based fertilizers.
Azadirachtin: active ingredient
The active ingredient of neem is azadirachtin (or rather azadirachtin A), contained in the tree and responsible for most of the useful properties of this tree. The greatest content of azadirachtin is found in the seeds, which are pressed to obtain the very useful neem oil. The squeezing of the seeds takes place cold and thus the insecticide is created which is then used in natural cultivation. As an alternative to oil, you can also find seed powder, to always be used in water and then sprayed on the plants trying to target the parasites.
On the market there are many products based on neem or azadirachtin: powders or sprays, you must be careful that they are not necessarily natural insecticides, since in the extraction of the molecule or in the final formula can also be used more toxic chemicals. Some of these products, on the other hand, are certified for use in organic farming and can therefore also be used in certified professional crops.
The percentage of azadirachtin contained in the natural oil changes between pure neem oil and derivative products, the presence of this molecule is low in natural oil, but it still has its effectiveness, on the market, there are products that have higher percentages and are therefore more powerful. For a family garden, it is better to choose to buy pure neem oil, to be diluted in water and used directly. It is a low environmental impact solution and generally cheaper than laboratory-made insecticides.
Toxicity and waiting period
The azadirachtin molecule does not pollute the environment: it is natural and easily degrades without accumulating in the soil or in water. For this reason, its environmental impact is close to zero and it can be used with more peace of mind than other insecticides, including organic ones, such as pyrethrum and spinosad.
Being harmless to humans and animals, it has a low shortage period, generally less than 7 days, the exact period depends on the crop and product used, however it should be checked on the package. For this reason, unlike various other insecticides, it can also be used in the presence of vegetables to be harvested relatively quickly.
However, there are different neem-based products on the market, often the formulations are very different from pure oil. Therefore, be careful that insecticides containing azadirachtin as an active ingredient can be more toxic and polluting than natural neem oil.
Neem and bees
Neem can annoy bees but does not kill them, unlike most other plant pest treatments.
To understand how much azadirachtin is respectful of bees, it is enough to know that in Mexico neem has been successfully tested to protect the hive from attacks by harmful mites (specifically varroa), thus treating insects directly, as the Federation tells us. Italian beekeepers.
This feature makes neem oil very suitable for use in the vegetable garden and orchard, we can also use it during flowering periods.
Use neem oil for plants
Generally, neem oil or seed powder is used by diluting them in water and spraying the liquid thus obtained on the plants. When using this insecticide it must be taken into account that the azadirachtin molecule is photosensitive, so for a better efficacy of the treatment, it must be carried out in the evening, avoiding doing it in broad daylight.
A side effect of this treatment is the smell: in fact, neem oil has a pungent and also very persistent stench.
Against which insects to use it
Neem oil has more than one effect: it is insecticidal, but also repellent (it repels insects), phagodeterrent (prevents insects from eating the leaves of the plant) and it is also able to inhibit the growth of parasites, while it is not significantly toxic for animals and humans and not even for many beneficial insects, including pollinators such as the aforementioned bees and bumblebees. We can therefore use it to defend ourselves from garden parasites and harmful insects in the orchard.
There are many insects unwelcome in the vegetable garden that undergo the repellent action of neem oil: for example, nematodes, beetles, noctuids, Colorado beetles, aphids, and cochineals, spider mites.
Neem is also good for containing fungal diseases such as powdery mildew and is successfully used to disinfect gardens from mosquitoes (read more: anti-mosquito neem).
Dilution and dosage
If you buy pure neem oil you must dilute it before use. There are also ready-to-use neem-based products on the market that are simple to mix in water because they are very soluble, but as already written, the advice is to buy pure oil, generally, you save significantly compared to the purchase of already mixed products.
The dilution of pure oil is not very easy, so it is advisable to use potassium soft soap (or Marseille soap) which, in addition to making the neem water-soluble, favors the adhesion of the nebulized solution to the plants and therefore improves its effect (read more dilution of neem oil).
The correct dosage depends on the use you want to make of it: which insect you want to target, whether it is for preventive purposes or to resolve an ongoing infestation. On average 5-6 drops of pure oil are enough for a liter of water, however, it is not necessary to go beyond 2%. To dilute it best you need to use warm water, which dissolves better, and remember to use potassium soap.
Buy pure neem oil or ready-made insecticide
Neem oil has many uses, even in cosmetics, so it can be found in herbal medicine or can easily be purchased via the internet, in various online shops. I know that many prefer to buy from Amazon, I do not recommend it but you can still find pure neem there too.
To facilitate dilution and to act as an adhesive agent on plants, as already explained, it is advisable to use soft potassium soap. So I recommend you buy this product too.
You can also easily find organic insecticides based on azadirachtin on the market, for example, Neemazal and Neem Plus are excellent. Personally, however, I recommend buying and using natural oil, for ecological and economic reasons. Certainly, however, the products have the advantage of greater simplicity in dosage and dilution, so even if they have a higher price, they can be useful for beginners or those with little time to devote.
For those wishing to learn more, I would like to point out some useful reading.
- A useful pdf on the use of azadirachtin in agriculture is available on the Emilia Romagna region website, by Alda Butturini of the regional phytosanitary service.
- Defending the garden with natural methods. A reading tip to deepen the topic of “natural insecticides” and learn how to use neem and other organic products to the fullest. I consider this book a fundamental text for those who want to make an organic garden.
You may be interested to read about the Red spider mite blogpost/ Powdery mildew blogpost/ Rock powders in agriculture blogpost/ Care plants with propolis blogpost/ Horsetail for diseases, parasites blogpost/ biological fungicide blogpost/ Feed plants with algae blogpost/ Whitefly on plants blogpost/ Italian straw pie recipe.