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CICLY · Lethal Yellowing Disease of Coconut Palm

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Some 'resistant' coconut palms can't resist lethal yellowing   Message List  
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Re: C I C L Y Some 'resistant' coconut palms can't resist lethal yellowing

Dear Dr. Hugh Harries,
Your letter was very informative.
It is well known that in most of the crops studied,resistance of any variety holds good only for a limited peiod and various reasons for overcomming the resistance of crop varieties are well documented.
It will be intersting to know how long a coconut variety can hold its resistance under intensive cultivation. Unless we know more about the pathogen, variations among strains , genetics of resistance etc.,  for cocnut lethal yellowing and similar diseases , it will be dificult to analyze the reasons for a resistant coconut variety becomming susceptible.
RV Nair 

Hugh Harries <hugh.harries@gmail.com> wrote:
Adrian

In today's (09/23/2007) Miami Herald, under the heading "Some 'resistant' coconut palms can't resist lethal yellowing" (http://www.miamiherald.com/1049/story/245761.html } you have written "LY has even been reported in palms native to Florida, Cuba, Jamaica and Hispaniola. Native palms frequently planted as ornamentals include cabbage palmetto, royal palm, Florida thatch palm  Thrinax radiata , and Key thatch palm  T. morrisii".

Would you accept that - so far - comparatively few native palms have been lost, when compared to coconut palms?

You continue "The disease has not been reported in exotic species such as the pygmy date palm, foxtail palm or queen palms".

But would it be more cautious to say "The disease has not YET been reported . . ."?

The point I wish to make is that there are degrees of resistance and that some palm species are more resistant than others - native palms and some exotics are more resistant than coconut, for example.

If you take that point then it follows that within any species some varieties are more resistant than others - the Maypan hybrid coconut is more resistant than the the Jamaica Tall - and even within any variety some individual palms are more resistant than others (although, in this last case, no one yet knows how to recognize in advance which palms will live longest).

This is not splitting hairs because it is important for anyone planting palms to know that "resistance" is the converse of "susceptibility" but is NOT the same as "tolerance" or "immunity". A tolerant palm would survive despite infection, an immune one would never become infected.

Maypan and Malayan Dwarf coconut varieties were originally claimed to be highly resistant but were never considered to be tolerant or immune.

Over the passage of some twenty or thirty years the susceptibility of these two varieties has increased or their resistance has decreased (the two phrases are interchangeable) but despite some hopes that the Fiji Dwarf coconut variety might do better or that an expedition to the Far East might discover other resistant varieties, the advice to anyone who wants to grow coconut palms is still the same - avoid the local tall and plant Maypan or Malayan Dwarf.

By all means recommend planting other palm species but, in the long term, even these might succumb if the LY pathogen or its insect vectors can overcome even their resistance, as they have with coconut.

Finally, please know that there is a Centre for Information on Coconut Lethal Yellowing (CICLY) which is intended to act as a clearing house for information about lethal yellowing and similar diseases of coconuts and other palms. Check the CICLY web site at http://www.cicy.mx/dir_acad/cicly/main.html or the CICLY discussion group at http://tech.groups.yahoo.com/group/CICLY/

Hugh Harries


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Tue Sep 25, 2007 1:26 pm

Velaydhan Nair <rvncpcri@yahoo.com>
rvncpcri
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Adrian In today's (09/23/2007) Miami Herald, under the heading "Some 'resistant' coconut palms can't resist lethal yellowing" ( ...
Hugh Harries
hugh.harries
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Sep 23, 2007
12:48 pm

Dear Dr. Hugh Harries, Your letter was very informative. It is well known that in most of the crops studied,resistance of any variety holds good only for a...
Velaydhan Nair
rvncpcri
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Sep 25, 2007
2:13 pm

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