In-the-know organic gardeners (and grandmothers) in Córdoba, Argentina will tell you an organic and powerful secret for pest control: the juice of the chinaberry, or the Paraiso, as it is known in South America.
Not surprisingly, these berries (which here are known as «venenitos» / «little poisons») contain a naturally-ocurring chemical compound which is has some of the same pesticidal properties of the more well-known neem tree extract.
This chemical, called Azadirachtin, inhibits reproductive cycles among treated herbivore pests, buts degrades organically and poses no threats to treated or surrounding plants.
Here’s a very interesting summary of many clinical studies on the chinaberry extract as an organic pesticidal and fungicidal agent. The Potential Uses of Melia Azedarach L. as Pesticidal and Medicinal Plant, Review by Adnan Y. AL-Rubae.
At all times when investigaing or using this plant, it is important to wear gloves, avoid inhaling any direct vapors, and never consume under any conditions, unless your are purposefully looking to consume nuero-toxic diuretic. In other words do not eat, and keep out of reach of pets and children.
One simple recipe for making the chinaberries usable in garden is by letting them soak in one liter of pure alcohol for one week, and later mix 1 part of the chinaberry-alcohol infusion to 3 parts water.
First we will need to remove the branches and leaves from the berries.
We are left with about 2 cups worth of chinaberries.
We drop all of the de-branched berries into the bottom of of a large plastic PET bottle. Then we dump the entire liter of alcohol into the bottle.
The chinaberries should be completely submerged in the alcohol. It is not advised to crush the berries at this stage, because we do not want to inhale toxic vapors. Additionally, after one week of soaking in the alcohol, we will see that a great deal of the characteristic green juice has naturally soaked out of the berries without ever having to crush them.
After soaking for one week (and shaking a few times during the week), the alcohol infusion has absorbed the berries’ green color, as well as their pesticidal content. This mixture is now ready to mix in a spray bottle, one part chinaberry alcohol to 3 parts water. When applying to plants it is recommended to wear a dust mask so as not to breath in the chinaberry vapors.
When applying to garden plants observe over a few days to make sure the plants show no signs of chemical burn. If so, add more water to the mix for further use.
Gnognos de Jardin 
Update:
We’ve been using this diluted chinaberry infusion for a few months on various horticultural and garden plants (those affected by leaf-eating pests or fungus), and have seen great results (no leaf burn, reduction or elimination of pest problems on plants, retardation or total stoppage of fungus on affected leaves.)
Some of the plants weave used it on are Ruda Hembra, brocolli, rucula and black bean plants, to name a few.
Great instructions! Just wanted to know, it´s not good to breathe it when you use it on the plants, but it’s safe to consume the plants you spray it on? I want to use it in my veggie garden but don’t want to get intoxicated… Thank you very much.
Hi Lelia –
THanks for your comment. According to the wikipedia page for Chinaberry’s active pesticidal component Azadirachtin:
Azadirachtin is biodegradable (it degrades within 100 hours when exposed to light and water) and shows very low toxicity to mammals (the LD50 in rats is > 3,540 mg/kg making it practically non-toxic).
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According to the bit above, it degrades after 100 hours. I never noticed any leafburn when applying it on plants either. So far we’ve seen the spray work on some bugs, and less so with others.
As far as wearing a mask when I applying, it’s not a bad idea.
Stay in touch,
Scott
Just wondering it anyone ever tried making China Berry Tea by putting it in a glass jar and leaving it sit in the sun.
I don’t recommend anyone makes tea or ingests any liquid infused with any part of the Chinaberry tree. I have one growing over my house. Without knowing of the side-effects, I used to collect the rainfall runoff from my roof and pipe it into a large tank and had that plumbed internally. The flowers are prolific and very sticky form a cement over my roof and then rainfall leaches out the azadiractin and other toxins into my 30,000 litre tank . It will give you diarrhoea and makes hayfever worse and gives you a long term headachey dopey malaise (and that’s from showering in it but not drinking it). Spraying it on plants wont affect insects or some plants as its applied topically. But azadiractin is similar to the neonicotinoid pesticide imidacloprid (responsible for large scale bee colony failure) in that it is systemically taken up by plants through their roots and sap sucking insects die from eating cambium sap over a few days to a week. I have lost many garden and vegetable plants after irrigating with my contaminated rainwater and it has killed my lawn. This is nasty toxic dangerous stuff which might have beneficial uses if you study the chemistry and application pathways but be warned. I have to remove my tree and scour the tank to restore my water supply safely. Putting it down the stormwater drain probably poses contamination risk to the river. Should get it tested before disposing it.
Thank you so very much for the information. I just have a few questions:
1. Do you cover the container when soaking the berries in alcohol or do you leave it wide open?
2. Do you reuse the berries after soaking them in alcohol? Is it possible the now crush the alcohol soaked seeds and make another pesticide?
3. Can the seeds be planted after soaking in alcohol?
Hi Josa – Thanks for the question.
1. Keeping in mind the possible toxicity of this preparation, especially when inhaled, I would say always keep the container sealed. I’ve also made a batch of this stuff in pure water, which also seems potent enough. The first time I did this I used alcohol, but that was because of a suggestion that was passed on to me. I’m not entirely sure what role alcohol plays since the pesticidal, fungicidal properties come from the berry.
2. I would imagine that after a long soak, the best part of the pesticidal substance (which comes from the fruity part of the berry) gets soaked into the alcohol/water content of the preparation. The dried berries are well known handicraft materials especially when sun dried, and I think this usage (craftworks) must be permitted because the seeds themselves don’t contain a high concentration of the pesticidal substance, especially when sun-dried. That’s my educated guess. The other reason for not processing or crushing the seeds a second time is because you really want to avoid breathing this liquid if possible. It’s better to go looking for more raw berries and only handle/soak raw berries using gloves. Even when spraying plants (I’ve been experimenting lately with good results on my green pepper plants) I’ve used a facemask or a cloth. The fumes are mildly toxic.
3. I would imagine that the seeds are not going to be ‘live’ after soaking in alcohol for any period of time. As for a soaking in pure water, that may be another matter.