Yes, neem trees lose their leaves every year, sometimes multiple times but, if a tree ends up with dead leaves up in the canopy then there is a problem due to an external factor. Yes, neem dieback has been around for some time and some trees recover from it. All neem trees that I have inspected have been affected by this to some extent. Older trees, very young trees and trees in poor condition or environments will likely be the most affected.
In the image below is the tea mosquito (Helopeltis antonii) which is one way that the fungus (Phomopsis azadirachtae) is transimitted which then causes the specific neem dieback disease (scientific evidence below).
Why do I think this is an issue now?
Because we have had successive drought years and a very wet year both of which can be detrimental for neems. Some of the trees have been defoliated twice in two years and some even more. Repeated defoliation of trees can lead to tree death.
Generally, all trees can be vulnerable to drought, especially to prolonged drought. It depends on their condition and the extent of the drought. With regards to excessive rain, if the roots are submerged for an extended period, they will not get oxygen, so they won’t be able to sustain their system (they can’t burn sugars). This FAO document mentions drought and neems. It is how I eventually came to the conclusion that the neems will not be able to deal with this very well (but it is likely to be consisting of even more factors).
The succession of detrimental events is the usual course for the death of a tree. Unlike us, they are not programmed to die. So, if a tree is affected by a disease, it is then more susceptible to other diseases.
And finally, yes, there are dead neems around.
Media (pics and videos):
Pictures of affected trees: https://photos.app.goo.gl/q7R5zAGFuLaGWuA79
Neem Dieback Treatment:
What we are doing is making neem trees more resistant to this disease and improving growing conditions in general for them and all surrounding vegetation.
Method and instructions of what we are doing (anyone can do it): Neem Treatment.
From what I understand (or think I understand) the C4 compost acts a positive environment for germination for the bacillus which then will merge with/inoculate the absorbing roots (which will also be prompted to grow due to the new richer environment, hence the combination). Then the Bacillus will induce systemic acquired resistance (which should help with the Phomopsis) along with potentially helping with uptake of water and nutrients through synergies with mycorrhizal fungi.
Other Potential Neem Dieback Treatments:
Antifungal activity of essential oils against Phomopsis azadirachtae- the causative agent of die-back disease of neem: http://www.ijat-aatsea.com/pdf/Jan_v6_n1_10/14-57-IJAT2009_37F.pdf
In Vitro Evaluation Of Antagonistic Microorganisms For The Control Of Die-Back Of Neem Causal Agent Phomopsis Azadirachtae: https://journals.pan.pl/Content/106234/PDF/JPPR_49(4)_04_Girish.pdf
Integrated management of Phomopsis azadirachtae, the causal organism of die-back of neem: https://www.researchgate.net/profile/Girish-K/publication/264657481_Integrated_management_of_Phomopsis_azadirachtae_the_causal_organism_of_die-back_of_neem/links/55f306d308ae7a10cf87a7f4/Integrated-management-of-Phomopsis-azadirachtae-the-causal-organism-of-die-back-of-neem.pdf
Efficacy of combinations of hexaconazole and bacterial extracts against Phomopsis azadirachtae, the die back of neem pathogen: https://www.researchgate.net/profile/Girish-K/publication/264657118_Efficacy_of_combinations_of_hexaconazole_and_bacterial_extracts_against_Phomopsis_azadirachtae_the_die-back_of_neem_pathogen/links/5f1404cca6fdcc3ed7154396/Efficacy-of-combinations-of-hexaconazole-and-bacterial-extracts-against-Phomopsis-azadirachtae-the-die-back-of-neem-pathogen.pdf
To give an idea of what could be affected, when surveying about half of Auroville excluding the “Greenbelt” (~2.5 square kilometres) Geomatics have recorded over 3000 neem trees. So there are potentially over 20,000 neem trees in Auroville.
Here is what has been achieved in Auroville, regarding treatment, so far (I am only involved in some of this):
|Number of Trees
|Joy of Impermanence
|20+ (with ecological horticultural course students)
|several, goal is 200 trees
|70+ trees (with TLC students and others)
It has now spread to 4 states: https://news2in.com/neem-trees-in-telangana-hit-with-dieback-disease/
We could be looking at millions of trees dying.
If you want to help:
Please get in touch. You can help by:
- Coming in person to apply treatment on Tuesday mornings from 8:30 (contact to confirm location)
- Learning the application method and doing it wherever
- Spreading the info
- Getting others to do it
- Contributing financially (it costs about RS55 per tree just for the materials and we are all doing this for free) by using the temporary Auroville FS account for this: 253042
- Letting me know if you have other methods which work
- Inspecting the trees, plotting them and then monitoring them to see how the treatment is acting
I am happy to come by (locally) and explain, show, teach (can be part of a school or research project).
Please let me know if you treat trees somewhere so we can record it (to later check if it works as intended and get statistics. If you want to be involved in this aspect, that is also possible).
This is the first step in setting up a response to a potentially huge loss of neem trees. All networking and collaboration could be improved and should be and if you want to coordinate efforts, please do so as I do not need, or necessarily want, to be involved.
If you have any other ideas, please suggest them (especially if you want to do the legwork).
Links to documentation:
Crude toxin extract from culture filtrate of Phomopsis azadirachtae infecting neem and its phytotoxicity: https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.555.1928&rep=rep1&type=pdf
Paper on effectiveness of the one of the strains of bacterium we use: (Bacillus subtilis): https://academicjournals.org/article/article1381737132_Girish%20et%20al.pdf
Variation in Phomopsis azadirachtae , the incitant of die-back of neem: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.1024.9357&rep=rep1&type=pdf
Another Article about one of the strains of Bacillus that we are using in our treatment.
Development of a simple and reliable species-specific detection of Phomopsis azadirachtae, using the translation elongation factor 1-alpha gene: https://drive.google.com/file/d/1_x-pdWL6AvMYr-8tTQEgFH98fLxu-IPv/view
Abstract of a paper stating that this is quite common in TN: A survey of die-back disease of neem in Tamil Nadu, India and PCR-based confirmation of the isolates: https://www.tandfonline.com/doi/full/10.1080/03235400903057613?scroll=top&needAccess=true
FAO: A Guide to the Identification of Diseases and Pests of Neem (Azadirachta indica): https://drive.google.com/open?id=1pRzoYuZS30WCuUyMiLhIU6kc76UF4Kvl&authuser=island%40auroville.org.in&usp=drive_fs
Many people think neems are the toughest trees around and will manage “no worries” which begs the question of “why are they affected in the first place?”