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CICLY · Lethal Yellowing Disease of Coconut Palm

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Reply | Forward | Delete Message #2179 of 2180 |
Re: LY and YLD (yellow leaf disease of Areca.

Dear Hugh,

May I ask the correspondents concerned about yellowing palms on the
subcontinent if they have knowledge of the herbicide history of
their respective plantations? I refer particularly to herbicide used
directly onto soils in which the affected trees grow.

Is it possible in any of these cases that the roots of the sick
plants have been able to take up residual weed control chemical?

--- In CICLY@yahoogroups.com, "Dr. K. Muralidharan"
<kmurali_cpcri@...> wrote:
>
> Dear Dr. Rajendra,
> Thank you for sharing your views and I will communicate the same
to my fellow scientists. As you said, we are only thinking loudly
and not meant to question the sincere efforts of the research
workers. But I am disturbed to see the plight of the coconut and
arecanut farmers of India and that made me to comment like this. I
sincerely wish interaction with you and like minded people will
throw more light on these matters.
> With regards, Muralidharan
>
> rajendra tk <tkrajendra@...> wrote:
> 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" <kmurali_cpcri@...> wrote:
> 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.
> Muralidharan, K.
> Sr. Scientist
>
> subramanya_machikoppa <subramanya_machikoppa@...> wrote:
> --- In CICLY@yahoogroups.com, "m govindan pilicode"
<mgpilicode@>
> wrote:
> >
> >
> > From,
> > Dr.M. Govindan, Professor Dept of Microbiology&Pl.Pathology.
> > Kerala Agricultural University, College of Agriculture,
> > Padnakkad. Kasargod. India.
> >
> > Sir,
> > 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
> > Govindan
> >
> hello Sir,
> My advice is-u just tell to CPCRI scients. They see the sample
under
> electronic microscope and tell wheather phytoplasma is present or
> not.
> 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.
> Yours'
> Subramanya Machikoppa
>
>
>
>
>
>
> ---------------------------------
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>
> Dr. Rajendra T. K.
> Center for Human Genetics,
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Tue Oct 16, 2007 12:45 pm

"jim.mcna" <juilmc@optusnet.com.au>
jim.mcna
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Message #2179 of 2180 |
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  From, Dr.M. Govindan, Professor Dept of Microbiology&Pl.Pathology. Kerala Agricultural University, College of Agriculture, Padnakkad. Kasargod. India. Sir, ...
m govindan pilicode
mgpilicode@rediffmail...
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Oct 10, 2007
11:30 pm

Since electron microscopy is expensive and tedious, preliminary screening of plant samples using phytoplasma specific stains like Diens stain and DAPI stain is...
jacob daniel
jacobandjaco...
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Oct 11, 2007
9:36 pm

... 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...
subramanya_machikoppa
subramanya_m...
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Oct 11, 2007
9:36 pm

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...
Dr. K. Muralidharan
kmurali_cpcri
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Oct 12, 2007
4:48 pm

Dear Dr Muralidharan, Why are you accusing Professor Govindan of making an "early warning" more than 10 years after he published a paper on the subject? All he...
Hugh Harries
hugh.harries
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Oct 13, 2007
6:19 am

Dear Dr. Muralidharan, I highly appreciate your very appropriate comments, especially given the fact that I/we ourself own areca plantations with a sceintific...
rajendra tk
tkrajendra
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Oct 14, 2007
6:55 am

Dear Dr. Rajendra, Thank you for sharing your views and I will communicate the same to my fellow scientists. As you said, we are only thinking loudly and not...
Dr. K. Muralidharan
kmurali_cpcri
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Oct 15, 2007
5:23 am

Dear Hugh, May I ask the correspondents concerned about yellowing palms on the subcontinent if they have knowledge of the herbicide history of their respective...
jim.mcna
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Oct 17, 2007
6:34 am

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