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How to Use Neem Leaf as a Natural Pesticide

Mary is an organic coconut farmer. In her articles, she shares ideas on land management and how to increase the profit from a small farm.

Neem leaves can be used as a natural pesticide.

Neem leaves can be used as a natural pesticide.

What Are Neem Trees?

I'm an organic coconut farmer living in Brazil. Here on my farm, I use a natural pesticide made from the leaves of the neem trees that we have growing here. Today, I would like to show you how we do this.

For those of you who aren't familiar with the neem tree (Azadirachta indica), it is an evergreen tree that is found in tropical and sub-tropical areas. The neem tree has many uses including medicinal, culinary, and as we use it on our farm, as a deterrent to pests. It's related to the curry tree but where a curry leaf tree is called a sweet neem, this neem is considered bitter. The tree grows rapidly about 10 feet a year and the seeds are encased in a skin that is surrounded by a juice.

Some of the birds we have here will suck the juice out of the berry and others swallow it whole. The monkeys love them as well and can often be seen sitting in the trees eating them. The bats take the berry and fly off with it, causing young neem trees to be scattered around bases of many of our trees here and on my veranda. The juice that surrounds the seed is okay for the animals but I have tried it and it is bitter and unpleasant.

These trees are a common sight in Brazilian city centers for their mosquito repellent properties and because they are fast-growing trees. The dark green serrated leaves are also attractive and are excellent as a dense shade tree. They are also resistant to drought. In fact, too much water will damage the roots and cause the leaves to turn yellow.

Cutting Neem Leaves for Pesticide

Cutting Neem Leaves for Pesticide

Using Neem Leaves as a Pesticide

We have 400 dwarf coconut trees that we spray with our neem pesticide. Please don't get too hung up on the term pesticide. It isn't killing the bugs; it prevents them from chewing the leaves of our trees. If the insects are solely reliant on eating coconut palm leaves, they will eventually starve, or at least on our farm.

Unlike a commercial product that kills the insect on contact, this doesn't occur when using this neem mixture. We are coating the plant leaf with a substance the insects don't like. Instead of killing the insect, we are protecting the plant.

We use this natural pesticide to guard against:

  • aphids
  • whitefly
  • grasshoppers
  • caterpillars

These are the primary insect problems that we deal with on our farm. Although we spray regularly, we also daily check our trees to stop an infestation before it happens.

I want to clarify that this article is about using the neem leaf.

For a more concentrated version of the pesticide, neem oil can be extracted from the seed by grinding down the dried seeds into a powder. This powder is then reconstituted with oil. If you don't have access to neem trees or you prefer to purchase neem oil, this is produced from the seeds, not the leaves.

The neem oil, although more effective than using the neem leaves, is less pungent to smell.

** Update**

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Read More From Dengarden

  1. As I am writing this in the middle of December 2019, our neighbours, both upwind and downwind, suffer from an infestation of whiteflies on their cashew trees. We have three mature cashew trees here on our farm, and although they haven't been sprayed with the neem solution due to their size, we don't have any whitefly. My husband believes it will be in our best interest to spray our upwind neighbor's trees and also near our fence. This will make an unpleasant barrier for the whitefly and hopefully confine them to a smaller area.
Removing neem leaves from stalks

Removing neem leaves from stalks

Removing the Leaves

Once cut, we bring the small cluster of branches back to our patio area. This next part of removing the leaves from the stems is time-consuming and also hurts the back. It isn't that it is difficult to do, it is just repetitive, and we have yet to find an easier way to do it.

We sit down and drag our hand down the stem allowing the leaves to drop into the bucket. We continue doing this until our bucket is full, and then it's time for the next step, which takes place in the kitchen.

Cuttning neem leaves with a food processor

Cuttning neem leaves with a food processor

Chopping up Neem Leaves

To chop up the neem leaves, I use my food processor. I fill the container without packing them too tightly. As I put the leaves in, I ensure no stems or seeds go in as they may damage the food processor's blades.

I then switch the machine to pulse until I see movement at the top; only then do I turn it on high. If I switch it on high from the start, I will end up with finely chopped leaves at the bottom of the processor and uncut leaves on the top. What you want are leaves roughly the same size.

This could be roughly chopped using a cutting board and a knife if you don't have a food processor or blender. To clarify, I'm not adding any liquid to this. I am just chopping up the leaves.

Making Neem Tea

I use the word tea as it is just the stewing of leaves in water. We don't use warm water for this, just our normal well water from our faucet.

The bucket of chopped-up leaves is put into a 50-liter plastic barrel. We fill this half full of water, put the lid on, and leave it for three days to brew.

You'll know if your mixture is ready as it will smell like a cross between urine and onions. Not a pleasant smell but effective against insects. Because of the smell, you may want to make the mixture away from the house.

Adding Oil and Detergent

Using another barrel, we strain the mixture which has brewed for 3 days, through a nylon mesh sieve. An old t-shirt works equally as well. This removes the leaves and we are left with the mixture that will be sprayed on the trees. We need to remove anything that may clog our sprayer and a sieve or a t-shirt works well.

To make sure the pesticide sticks to the plants and doesn't just run off, we need to add oil and dish soap. For this, we use 3 ounces of cooking oil and the same amount of dish soap. The role of the dish soap is to break down the oil, and the role of the oil is to make it stick to the leaves.

The stewed leaves from your mixture can be used in your compost heap or around the base of your plants.

Here I am spraying one of our 400 trees.

Here I am spraying one of our 400 trees.

Using a Sprayer

As you can see from our photos, we use a backpack style sprayer. This carries 10 liters, which is a little more than 2 1/2 gallons. You may be able to handle a larger one but my husband is 69 years old, and an amputee. Walking from tree to tree with the sprayer on his back keeps the oil and detergent mixing because of the movement. If you were using a hand held spray bottle, a quick shake before applying is a good idea as the mixture may separate.

Ours is a hand-pressurized mechanism, which works off a lever on the left-hand side of the sprayer. We have extended the nozzle length on ours to ensure he can reach the upper leaves of the coconut trees without having to use a ladder, which would be too cumbersome to take from tree to tree.

Spraying Coconut Trees With Neem

Spraying Coconut Trees With Neem

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

Questions & Answers

Question: Once made, how long will neem leaf pesticide keep without going stale?

Answer: We use ours straight away. Any that you don't use should be poured away.

Question: Can I use dried neem leaves to make a natural pesticide?

Answer: Yes, by putting them in water to use as a spray or around the plant to decompose.

Question: What ratio of chopped leaves in kilos to that of water in liters should I use to create the pesticide?

Answer: We never weighed the leaves, but a full yellow bucket as you see in the photo, once chopped, resulted in a 50-liter container being one-third full of leaves. Then we filled the 50-liter container with water.

Question: Can neem repellent be used on edible leafy plants, like spinach? My worry is the bitter residue taste may remain and make them unpallateble.

Answer: I haven't tried it specifically for the reason you mention. When I see the residue on our coconut leaves I'm certain it will affect the taste. What I would suggest is that you used leaves, around the bases of the plants. These could be composted down but will still be beneficial without causing a change in the taste of plants such as spinach and lettuces.

The residue I am seeing is that iridescent look of the oil in the mixture. However, because the plants aren't being eaten by insects, I can assume, the residual bitter taste from the neem mixture is working.

Question: Can I use this neem tea to help grow seeds of ornamental and flowering plants?

Answer: I haven't tried it but I would say no. To give your seeds the best chance of survival, they need to be grown in a well thought out compost mixture. Neem spray would be too harsh for tender seedlings.

Question: How is the neem leaf spray effective?

Answer: The insects don't like the taste of the residue left behind. Using the oil and soap mixture helps it stick to the leaves of the plant. This creates a nasty taste and discourages the insect from eating the leaves that have been sprayed.

Question: Can ground neem leaf be used as fertilizer?

Answer: It most definitely can. Here on our farm, we always tip the leaves straight under a coconut tree or add the leaves to a composting area.

Question: How long can neem oil be stored?

Answer: In this article we are not using neem oil, only a neem tea from the leaves. The oil comes from grind the seeds. If you are purchasing neem oil, the package will have instructions for the best practices for storing it.

For our mixture of neem tea, we use the contents after it has had time to brew for a few days. Any that is left over, we discard. Because we have neem trees growing here on our farm, it is a renewable source.

Question: Is neem pesticide safe for pets?