Re: C I C L Y LY and YLD (yellow leaf disease of Areca.
Dear Dr. Muralidharan,
I highly appreciate your very appropriate comments, especially given the fact that I/we ourself own areca plantations with a sceintific career in Molecular genetics and Cell and Developmental Biology (of course not Botany). With many areca plantations in our vicinity (in and around around Sringeri, Karnataka, India) afflicted with lethal yellow disease (if I can use that term), I am familiar with the approach adopted by scientists to diagnose this disease. In general, they assume something and test for it and so they attributed this yellow disease of areca to phytoplasmas, mainly based on PCR (I do understand that electron microscopy is used by some, but that takes us only so far). That is OK if the results were conclusive. However, when questions were asked during informal/formal discussions before farmers, what they say is that the results were variable. Then, why do they say that the disease is due to phytoplasmas, which is especially
not expected of scientists. This conclusion has almost halted further research since once you believe an answer is known, you will not put further effort to know the answer that is already known. There were also some research on soil chemical constitution of affected plantations with no conclusive answer. I do know the existence of areca plantations wherein one side of the fence (separating two areca plantations owned by different farmers) has no disease, while the other side has it. Phytoplasmas and their vectors do not discriminate two sides of a fence. This argues for a disease typical of cadang-cadang viroids
that shares features similar to LYD, but has all the manifestations of our areca disease (the difference across the fence may be attributed to differing farming methods and equipments). Cadang-cadang viroid disease also helps explain differences in disease manifestation
across a fence (either side of the fence owned by different farmers with differing farming practices and equipments used), life span of diseased trees, the new pockets/centers of origin and the nature by which the disease spreads. I also do remember some people telling me that only when they changed workers for areca cropping that they started having disease in their plantation, again arguing for cadang-cadang
viroid (that is why (as a precautionary method) I have told my brothers that we should not use sickles and other farming equipment borrowed from others (even if the disease is not due to cadang-cadand vidoid), unless they are chemically treated (for example, bleach) for destroying nucleic acids).
In any case, I do not argue for one or the other theory, but would like people to think without any constraint so that a way out to address this problem can be found. Even the cadang-cadang angle needs to be
tackled scientifically, than just by logic as I have done here. There may also be other reasons for lethal yellowing of areca, and quite possibly for coconut,other than phytoplasmas and cadang-cadang viroid, like the type of side crops, weeds etc, but one needs a comprehensive analysis of the affected plantations that results in very consistent results, expected of scientists with scientific way of thinking. This communication is not to question anybody, but am asking some simple questions on the lethal yellowing of areca that may help various affected farmers. I highly appreciate Dr. Muralidharan's mail especially in this regard and this mail has nothing to do with Dr. Govindan on coconut disease (note that Dr. Govindan used the term "similar" to Lethal Yellowing, not just "Lethal Yellowing" and hence looking for a conclusive test).
Rajendra "Dr. K. Muralidharan" <firstname.lastname@example.org>
This is for the kind attention of all scientists:
If a farmer is saying that there is LYD symptoms or similar to that, one can appreciate.
But a scientist should not make such early warnings. No body in India prevents the coconut pathologists to interact and confirm or disprove the hypothesis.
subramanya_machikoppa <email@example.com> wrote:
, "m govindan pilicode" <mgpilicode@...>
> Dr.M. Govindan, Professor Dept of Microbiology&Pl.Pathology.
> Kerala Agricultural University, College of Agriculture,
> Padnakkad. Kasargod. India.
> Greetings. In Kerala I have seen some coconut plants showing
symptoms almost similar to Lethal Yellowing.(M.Govindan et al. 1996.
Indian coconut journal. 2-4) Now similar reports are appearing from
other parts of the country also(Bhaskaran et al. 2007.Indian coconut
Journal: 2-4). I would like to have a few samples tested for the
presence of phytoplasma. Kindly suggest the persons whom I can
contact for help.
> Thanking you
My advice is-u just tell to CPCRI scients. They see the sample under
electronic microscope and
tell wheather phytoplasma is present or
The same they did in case of areca yellow leaf disease.(I have the
book they published on it)
CPCRI is there,near u,in Kasaragodu.
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Dr. Rajendra T. K.
Center for Human Genetics,
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Sat Oct 13, 2007 8:28 pm
rajendra tk <firstname.lastname@example.org>