A part of the “green revolution” of the 20th century were synthetic pesticides and fertilizers. They were so effective in killing pests that they soon became a staple product in all plant operations – including large agricultural fields and small home gardens.
Despite our advances in pest control technology, we have only recently discovered the dangers and hazards associated with synthetic pesticides, and it has turned out that their chemical structure could be the cause of many processes that are harmful to natural ecosystems and human bodies. The once widely used pesticide DDT has been deemed a carcinogen, while other pesticides pose a threat to global bee populations.
These are the main reasons why people have started using organic fertilizers and pesticides. Since so many insects eat plants, they have developed sophisticated chemical mechanisms to protect themselves. These chemicals can be derived from plants, making them more effective insecticides for humans and their pets.
What is Neem Oil?
Neem trees have been shown to be exceptionally effective at controlling pests.
Native to India, the marvel plant is known scientifically as Azadirachta indica. Neem has long been revered there as a sacred tree, as it is an essential component in traditional Indian Ayurvedic medicine.
In both traditional and modern medicinal applications, neem oil is especially prized as an ingredient for cosmetics and insect repellents. And it is this last application that we are most concerned with.
Insecticidal capabilities of neem oil make it an perfect ally in the garden. In a sense, it’s a gift from nature to plants.
What Is Neem Oil Made Of?
This is why neem oil is extracted from the seeds’ kernels, which may account for 50% of the seed’s weight.
It is used to control pests and enhance soil fertility in gardening and agriculture. Neem cake is generally comprised of the kernel remains. Interesting to note, the cake is also used in organic livestock farming in an alternative way to antibiotics – it is added to animal feed to fight parasites, bacteria, and fungi.
How Can Neem Oil Kill Insects?
Neem oil has an adverse effect on over 200 species of plant-feeding insects, and there are claims that this number is as high as 600! Some common pests include mealy bugs, cabbage worms, thrips, whiteflies, mites, fungus gnats, mushroom flies, locusts, beet armyworms, and other leaf-feeding insects.
A component called Azadirachtin is what makes neem oil work as a pesticide. It acts as an insecticide and repellent by disrupting insect feeding and growth.
Azadirachtin inhibits insect reproduction by blocking their ability to feed on plants, preventing them from maturing into larvae or adults. In a short amount of time, the colony of damaging insects will die out.
Additionally, neem oil interferes with insects’ metabolisms and repels them with its strong aroma, making the plant unpleasant to consume in the first place.
Neem Oil Uses in the Garden
Additionally to insecticide properties, neem oil also offers nematode worm control, as well as the ability to combat other well-established fungal diseases such as powdery mildew, black spot, and rust fungi. According to some, neem oil can even guard against plant virus infections.
How To Use Neem Oil Properly?
For your garden, you have two options for using neem oil.
You can purchase commercial neem oil for gardening because the store-bought versions (usually) have been tested and are safe to use. You can also buy ready-to-use products instead of gathering and mixing the ingredients yourself.
However, store-bought neem oil products often contain less azadirachtin than the pure oil you could make at home, which may make them less effective in treating your pest problem. They may also contain additional compounds you don’t want to have in your garden.
Additionally, brand-name neem oil sprays might not be available in your area due to some legal limitations covered in the next section.
Besides buying neem oil spray, you can make your own in a few minutes. This option has a couple of advantages and disadvantages, like the store-bought method.
DIY neem oil sprays let you pick the ingredients and concentrations you are willing to use in your garden – and you can tune your policy according to your observations and experience, such as altering dosage levels based on the kind of pest you are targeting.
The solutions and their ingredients can have a lot of effect on the plants, and some of these reactions can be quite bad. Therefore, it is important to be extra-cautious with DIY sprays. Different plants react differently to house-made solutions and their components.
Making your own insect repellents can be tricky, but here is a general rule of thumb: do not blindly believe in the efficacy and safety of DIY formulations without adequate testing. It is possible for some DIY sprays, including neem oil ones, to damage or kill plants if you do not run a test run first. This applies to all DIY sprays, including neem oil ones.
The formulation you choose should be tested on a small portion of the plants first and then observed for 24 hours.
Neem Oil DIY Formulations
I have outlined above that homemade neem oil insecticides can be more potent than commercial ones. By carefully selecting the neem oil, you will get a high level of azadirachtin -the active compound that kills pests.
Ensure your neem oil is 100% pure, cold-pressed – these are often referred to as raw or crude oils. Cold-pressing is essential since Zadirichtin is destroyed by heat, so heat-derived oils won’t contain enough of this beneficial component.
Alternatively, by purchasing organic neem oil, you will avoid any contamination caused by chemicals or solvents that may be present during the standard, noncertified purification process.
Preparing Your Neem Oil Spray
You won’t need many ingredients to make a neem oil spray – just the oil itself, water, and an emulsifier. Don’t let that last word scare you, because the deal is simple. Oil and water do not mix, so you will need to add a mild liquid soap (an emulsifier) to the mix.
Basic Neem Oil Insecticide Spray – Instructions
For making 1l of a basic, mild 0,5% neem oil spray, you will need:
- 1-quart (1l) of warm water
- 1 teaspoon (5ml) of neem oil.
- ⅓ tsp (1-2ml) of mild liquid soap, insecticidal soap or another mild detergent. Other sources say that 1 tsp of soap is also fine.
Shake the water and soap in a closed bottle until the soap is fully dissolved, then add the neem oil and shake again.
The concentration of 0,5-1% is the most common for general and regular garden use, although you can experiment with 2% sprays if you think you need a stronger solution. How To Use The Neem Oil Spray?
It is imperative to test the neem oil spray first before using it generously. It is impossible to overstate how important this is.
Spray your solution on the affected leaves, but only on one area of the plant at first, so you can observe any adverse effects. If the plant appears to respond well to the spray after 24 hours, you can proceed to spray the whole area.
You can use neem oil spray either when you need it, or regularly; once a week is a good regimen. Most importantly, regular use makes it a preventive solution, so it can help you avoid future pest infestations.
As with other oil-based sprays, it is important for the active ingredients to completely cover the leaves, otherwise insects and fungi pests will not be able to contact them.
Neem oil sprays should be used according to the following safety guidelines:
- Never use your neem oil spray in direct sunlight.
- Do not spray your plants in extreme temperatures, both hot or cold.
- Do not treat the plants that have been stressed with bad growing conditions, such as drought or overwatering; improving the plant’s conditions prior to spraying is important to avoid adding damage by spraying.
- Keep the neem oil and the neem oil spray in a safe place to avoid ingestion by children or pets.
Neem Oil Toxicity And Safety
It would be naive to assume that Neem oil is completely safe for other animals at all doses and circumstances, given its bioactivity and potency in combating insects and infectious agents.
Pure neem oil has been reported to cause severe toxicity in humans – 20ml of orally administered pure neem oil can cause vomiting, convulsions and toxic encephalopathy. Children’s livers may suffer adverse effects along with their fertility.
Therefore, groups that should stay away from any neem products – not just neem pesticides – are women trying to conceive, pregnant women, and children.
The EPA recognizes neem oil-based products as safe, so any residue on your produce is acceptable. However, although neem oil is an organic pesticide, all fruits and vegetables that have been treated with neem sprays should be washed in clean water thoroughly before use. This goes for any edible veggies or herbs from your garden, sprayed with any solutions.
Is Neem Oil Legal To Use?
Pesticides containing azadirachtin, including products containing neem oil, might not be readily available in the UK or in the European Union, since those products are controlled and regulated.
Having said that, if you raise organically certified products, consult your local organic agricultural society and licensing bodies first to make sure the use of neem-based products is acceptable. Conclusion
Plants are compact chemical laboratories and contain many compounds that can help us control many diseases in our gardens, especially insect infestations. And since these molecules are naturally occurring, the damage they can do to their surroundings is much smaller than with man-made pesticides.
Neem tree is one such plant. It is one of many ways that organic gardeners can have the benefits of neem oil sprays, while also ensuring their safety. Neem oil sprays foster a more organic garden while providing a safe chemical weapon against pests. As far as we know, the toxic effects of neem oil sprays are limited to insects that feed on leaves and vegetative organisms such as nematodes.
It might be worth exploring what nature has to offer before resorting to synthetic pesticides, which need to be used with extra caution as they can harm human and animal health and affect biodiversity.