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Lethal yellowing is a phytoplasma disease of coconut
and other palms. Susceptible palms die within 3 to 6 months of the
first symptoms. It is epidemic on the Gulf and Caribbean coasts of
Mexico and in Belize and Honduras where hundreds of thousands of
palms are dying. Areas with millions of coconut palms on the
Caribbean and Atlantic coasts of other Central and South American
countries are at risk because the common variety is highly
susceptible. But previous outbreaks in Caribbean islands like Jamaica
are no longer epidemic because rehabilitation schemes have replanted
with resistant varieties and hybrids. Diseases with a phytoplasma
etiology also occur on coconut palms in West and East Africa.
Phytoplasma have recently been associated with coconut diseases in
southeast Asia. It has been suggested that resistant varieties
co-evolved with the disease in that region. Hopefully, coconut palms
on the Pacific coast of America will show a natural level of
effective resistance because they have a closer relation ship to
southeast Asian coconut varieties than to the Caribbean or Atlantic
When the disease was active in Jamaica and Florida, in the 1960s and 70s an International Council on Lethal Yellowing (ICLY) was set up. It was supported by the FAO, the Coconut Industry Board, Jamaica, the UK Overseas Development Administration, the University of Florida and the International Palm Society, amongst others. Four meetings were held where scientists from a variety of disciplines could discuss ideas. The first meeting took place at Fairchild Garden in 1973, the second in Jamaica in 1975 (concurrently with the 4th FAO Technical Working Party on Coconut Production, Protection & Processing. Summary reports were published of these and a list of titles at the second meeting was given in the FAO Coconut Breeders' Bulletin for 1975. The third and fourth ICLY meetings were both held in Fort Lauderdale, Florida in 1977 & 1979 (and proceedings were published in 1978 & 1980). In addition to LY disease in the Caribbean region, similar diseases in West Africa (Kaincopé, Cape St Paul Wilt etc) were also dealt with by participation of scientists from Ghana and Ivory Coast.
Unfortunately, ICLY did not continue into the 1980s. There were various reasons. For a start, there was the cost of bringing people together for meetings. Then FAO discontinued the Commission on Coconut Production, Protection and Processing in 1980. The very success of work in Jamaica, that brought the disease under control by replanting with Malayan Dwarf and Maypan, meant that ODA support could be directed elsewhere (for example, to coconut tissue culture). In Florida, tetracycline therapy (combined with replanting resistant material) made control a commercial activity while the passing of the Bumpers Amendment in 1986 discouraged any US funding for research into coconut.
The net effect was that when the disease began to spread in Mexico in the early 1980s, it was not treated as a regional problem. Now, by the end of the 1990s lethal yellowing is epidemic in parts of Mexico, Belize and Honduras and there is nothing that can stop it moving into other countries of Latin America. In West Africa, the spread of phytoplasma disease from a minor coconut area in the east of Ghana to the major area in the west increasingly threatens the Ivory Coast. In East Africa there appear to be similarities with the Caribbean phytoplasma despite disappointing response to the disease by introduced germplasm. Very recently, phytoplasma have been associated with two long standing diseases of coconut in Indonesia, Natuna Wilt and Kalimantan Wilt.
This is an area of very active investigation where different types of Lethal Yellowing caused by phytoplasmas, are identified and classified by means molecular technology, such as PCR, RFLP and rDNA sequencing. The possibility that the LY phytoplasma might be associated with diseases of other plants, such as the date palm or sugar cane, requires further investigation.
ICLY is now revived, with the benefits of electronic mail, as CICLY. In English this is the Centre for Information on Coconut Lethal Yellowing or Centro de Información del Amarillamiento Letal de Coco in Spanish (to acknowledge the inescapable fact that most research will take place in Latin America). CICLY is intended to act as a discussion centre and clearing house for information about lethal yellowing and similar diseases of coconut and other palm species. To participate, send in ideas for what you want to see or read about and who else should be contacted.
The following list of subjects is proposed but suggestions for other topics are welcome:
This page is under continuous review. If you have an idea or an opinion to improve the contents of the page or the site, tell the editor. If you disagree with anything, say so. If you don't see or get a satisfactory response in a reasonable time contact other participants. At all time keep in contact with other individuals; this site is not a substitute for person to person contact.
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