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Candidatus Phytoplasma palmae
(lethal yellowing (LY))

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Datasheet

Candidatus Phytoplasma palmae (lethal yellowing (LY))

Summary

  • Last modified
  • 10 December 2020
  • Datasheet Type(s)
  • Invasive Species
  • Pest
  • Natural Enemy
  • Preferred Scientific Name
  • Candidatus Phytoplasma palmae
  • Preferred Common Name
  • lethal yellowing (LY)
  • Taxonomic Tree
  • Domain: Bacteria
  •   Phylum: Firmicutes
  •     Class: Mollicutes
  •       Order: Acholeplasmatales
  •         Family: Acholeplasmataceae

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Pictures

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PictureTitleCaptionCopyright
Candidatus Phytoplasma palmae (lethal yellowing of coconut); aborted coconuts often develop a calyx-end rot.
TitleSymptoms
CaptionCandidatus Phytoplasma palmae (lethal yellowing of coconut); aborted coconuts often develop a calyx-end rot.
Copyright©N.A. Harrison
Candidatus Phytoplasma palmae (lethal yellowing of coconut); aborted coconuts often develop a calyx-end rot.
SymptomsCandidatus Phytoplasma palmae (lethal yellowing of coconut); aborted coconuts often develop a calyx-end rot.©N.A. Harrison
Candidatus Phytoplasma palmae (lethal yellowing of coconut); necrosis (blackening) of newly emerged inflorescence on the Atlantic tall coconut ecotype.
TitleSymptoms
CaptionCandidatus Phytoplasma palmae (lethal yellowing of coconut); necrosis (blackening) of newly emerged inflorescence on the Atlantic tall coconut ecotype.
Copyright©N.A. Harrison
Candidatus Phytoplasma palmae (lethal yellowing of coconut); necrosis (blackening) of newly emerged inflorescence on the Atlantic tall coconut ecotype.
SymptomsCandidatus Phytoplasma palmae (lethal yellowing of coconut); necrosis (blackening) of newly emerged inflorescence on the Atlantic tall coconut ecotype.©N.A. Harrison
Ca. Phytoplasma palmae (lethal yellowing LY); mid-stage foliar discolouration symptoms on the Atlantic tall coconut ecotype.
TitleSymptoms
CaptionCa. Phytoplasma palmae (lethal yellowing LY); mid-stage foliar discolouration symptoms on the Atlantic tall coconut ecotype.
Copyright©N.A. Harrison
Ca. Phytoplasma palmae (lethal yellowing LY); mid-stage foliar discolouration symptoms on the Atlantic tall coconut ecotype.
SymptomsCa. Phytoplasma palmae (lethal yellowing LY); mid-stage foliar discolouration symptoms on the Atlantic tall coconut ecotype.©N.A. Harrison
Ca. Phytoplasma palmae (lethal yellowing LY); late-stage foliar discolouration symptoms on the Atlantic tall coconut ecotype.
TitleSymptoms
CaptionCa. Phytoplasma palmae (lethal yellowing LY); late-stage foliar discolouration symptoms on the Atlantic tall coconut ecotype.
Copyright©N.A. Harrison
Ca. Phytoplasma palmae (lethal yellowing LY); late-stage foliar discolouration symptoms on the Atlantic tall coconut ecotype.
SymptomsCa. Phytoplasma palmae (lethal yellowing LY); late-stage foliar discolouration symptoms on the Atlantic tall coconut ecotype.©N.A. Harrison
Ca. Phytoplasma palmae (lethal yellowing LY); symptoms on palmyra palm (Borassus flabellifer).
TitleSymptoms
CaptionCa. Phytoplasma palmae (lethal yellowing LY); symptoms on palmyra palm (Borassus flabellifer).
Copyright©N.A. Harrison
Ca. Phytoplasma palmae (lethal yellowing LY); symptoms on palmyra palm (Borassus flabellifer).
SymptomsCa. Phytoplasma palmae (lethal yellowing LY); symptoms on palmyra palm (Borassus flabellifer).©N.A. Harrison
Ca. Phytoplasma palmae (lethal yellowing LY); symptoms on spindle palm (Hyophorbe verschaffeltii).
TitleSymptoms
CaptionCa. Phytoplasma palmae (lethal yellowing LY); symptoms on spindle palm (Hyophorbe verschaffeltii).
Copyright©N.A. Harrison
Ca. Phytoplasma palmae (lethal yellowing LY); symptoms on spindle palm (Hyophorbe verschaffeltii).
SymptomsCa. Phytoplasma palmae (lethal yellowing LY); symptoms on spindle palm (Hyophorbe verschaffeltii).©N.A. Harrison
Ca. Phytoplasma palmae (lethal yellowing LY); symptoms on edible date palm (Phoenix dactylifera).
TitleSymptoms
CaptionCa. Phytoplasma palmae (lethal yellowing LY); symptoms on edible date palm (Phoenix dactylifera).
Copyright©N.A. Harrison
Ca. Phytoplasma palmae (lethal yellowing LY); symptoms on edible date palm (Phoenix dactylifera).
SymptomsCa. Phytoplasma palmae (lethal yellowing LY); symptoms on edible date palm (Phoenix dactylifera).©N.A. Harrison
Ca. Phytoplasma palmae (lethal yellowing LY); symptoms on footstool palm (Livistona rotundifolia [Saribus rotundifolius]).
TitleSymptoms
CaptionCa. Phytoplasma palmae (lethal yellowing LY); symptoms on footstool palm (Livistona rotundifolia [Saribus rotundifolius]).
Copyright©N.A. Harrison
Ca. Phytoplasma palmae (lethal yellowing LY); symptoms on footstool palm (Livistona rotundifolia [Saribus rotundifolius]).
SymptomsCa. Phytoplasma palmae (lethal yellowing LY); symptoms on footstool palm (Livistona rotundifolia [Saribus rotundifolius]).©N.A. Harrison
Ca. Phytoplasma palmae (lethal yellowing LY); transmission electron micrograph (TEM) of phytoplasma in a sieve tube element of lethal yellowing-diseased princess palm (Dictyosperma album).
TitleTEM
CaptionCa. Phytoplasma palmae (lethal yellowing LY); transmission electron micrograph (TEM) of phytoplasma in a sieve tube element of lethal yellowing-diseased princess palm (Dictyosperma album).
Copyright©University of Florida
Ca. Phytoplasma palmae (lethal yellowing LY); transmission electron micrograph (TEM) of phytoplasma in a sieve tube element of lethal yellowing-diseased princess palm (Dictyosperma album).
TEMCa. Phytoplasma palmae (lethal yellowing LY); transmission electron micrograph (TEM) of phytoplasma in a sieve tube element of lethal yellowing-diseased princess palm (Dictyosperma album). ©University of Florida

Identity

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Preferred Scientific Name

  • Candidatus Phytoplasma palmae

Preferred Common Name

  • lethal yellowing (LY)

Other Scientific Names

  • 16SrIV-A phytoplasma
  • Candidatus Phytoplasma palmae-related strains
  • coconut lethal yellowing mycoplasma-like organism
  • coconut lethal yellowing phytoplasma
  • palm lethal yellowing phytoplasma

International Common Names

  • English: coconut lethal yellowing; lethal yellowing; lethal yellowing of coconut; palm lethal decline phytoplasma; palm lethal yellowing
  • Spanish: amarillamiento letal del cocotero; amarillez letal (Mexico); pudricion del cogollo (Cuba)
  • French: pourriture du bourgeon terminal du cocotier

English acronym

  • LY

EPPO code

  • PHYP56

Taxonomic Tree

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  • Domain: Bacteria
  •     Phylum: Firmicutes
  •         Class: Mollicutes
  •             Order: Acholeplasmatales
  •                 Family: Acholeplasmataceae
  •                     Genus: Candidatus Phytoplasma
  •                         Species: Candidatus Phytoplasma palmae

Notes on Taxonomy and Nomenclature

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According to phylogenetic analyses of 16S rRNA gene sequences, phytoplasmas constitute a monophyletic clade of prokaryotes within the class Mollicutes most closely related to the genus Acholeplasma (Gundersen et al., 1994; Sears and Kirkpatrick, 1994; Seemüller et al., 1994, 1998). Within the phytoplasma clade, numerous groups (labelled 16SrI through 16Sr were also differentiated by these analyses. A phylogenetic based taxonomy of the phytoplasmas has been proposed (ICSB Subcommittee on the Taxonomy of Mollicutes, 1993) in which subgroups (labelled alphabetically in the order of discovery) are considered to represent distinct species (ICSB Subcommittee on the Taxonomy of Mollicutes, 1997). Names under the provisional taxonomic status ‘Candidatus’ (Murray and Schleifer, 1994) are being assigned to a reference strain within each primary group (Zreik et al., 1995; Davis et al., 1997; White et al., 1998; IRPCM Phytoplasma/Spiroplasma Working Team Phytoplasma Taxonomy Group, 2004; Harrison et al., 2011). The palm lethal yellowing (LY) phytoplasma (Florida strain) and coconut lethal decline (LDY) phytoplasma, a distinct, albeit closely related strain from the Yucatan peninsula, Mexico (Harrison and Oropeza, 1997) represented one (subclade VII) of 11 subclades of phytoplasmas originally resolved by Gundersen et al. (1994). Phytoplasmas associated with lethal yellowing-like diseases of coconut in eastern Africa (lethal disease, Tanzania) and western Africa (Awka disease, Nigeria; Cape St. Paul wilt, Ghana) were differentiated from the LY and CLD phytoplasmas. They were assigned to new subclades XII and XIV, respectively, in more recent phylogenetic classifications (Liefting et al., 1996; Tymon et al., 1998).

In a related classification scheme based upon similarity coefficients derived from RFLP analysis of PCR-amplified 16SrDNA sequences, phytoplasmas were delineated into 14 major groups (termed 16Sr groups) and 40 subgroups (Lee et al., 1993, 1998a, b). A total of 45 strain subgroups were resolved when RFLP data derived from less-conserved ribosomal protein genes were also considered in these analyses. Differentiation and classification of phytoplasmas has been augmented by computer-simulated RFLP analysis (Zhao et al., 2009) of 800 phytoplasma 16S rDNA sequences. Based on distinctive virtual RFLP patterns and calculated similarity coefficients, the phytoplasma strains were most recently classified into a total of 28 groups (Wei et al., 2007). Within the RFLP classification system, the LY phytoplasma has been assigned to RFLP group 16SrIV (coconut lethal yellows group), subgroup A (16SrIV-A). Within group 16SrIV, five other related phytoplasmas have since been assigned as subgroup members, namely, LDY phytoplasma (16SrIV-B) and Tanzanian coconut lethal disease (LDT) phytoplasma (16SrIV-C) (Lee et al., 1998), Lethal bronzing disease (LBD) phytoplasma (16SrIV-D) (Harrison et al., 2002b), coconut lethal yellowing (LYDR-B5) phytoplasma (16SrIV-E) (Martinez et al., 2008) and Washingtonia decline (FP) phytoplasma (16SrIV-F) (Harrison et al., 2008).

Description

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Phytoplasmas are prokaryotes that lack a cell wall and are too small in size to be resolved adequately by light microscopy methods. By transmission electron microscopy of ultrathin sections, phytoplasmas appear to consist of rounded to filamentous bodies bounded by a trilaminar unit membrane. These bodies contain granules the size of ribosomes and strands of DNA that apparently condense during specimen preparation (Thomas, 1979; Thomas and Norris, 1980). In phloem sieve tube elements of coconut palms, cells of the LY phytoplasma are generally 142-295 nm in diameter and may vary from 1 to 16 µm in length (Waters and Hunt, 1980).

Distribution

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The disease is presently most active in the Caribbean; specifically, on the islands of Saint Kitts and Nevis (IPPC, 2012; Myrie et al., 2012); and has also been reported in Antigua (ProMED-mail, 2012). Areas currently affected in Saint Kitts include the northern and eastern portions of the island; the disease has been present on Nevis since 2005 (IPPC, 2012).  In addition, LY (16SrIV-A) is currently active in Jamaica, Mexico (on the Yucatan peninsula) and Puerto Rico. In Florida, USA, LY seems to have been replaced by LBD (16SrIV-D).

See also CABI/EPPO (1998, No. 264).

Distribution Table

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The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Last updated: 12 May 2022
Continent/Country/Region Distribution Last Reported Origin First Reported Invasive Reference Notes

Africa

BeninPresentOriginal citation: CABI/EPPO and (1998a)
CameroonPresentOriginal citation: CABI/EPPO and (1998a)
Côte d'IvoirePresent
GhanaPresent1937Original citation: CABI/EPPO and (1998a)
KenyaPresentOriginal citation: CABI/EPPO and (1998a)
MozambiquePresentOriginal citation: CABI/EPPO and (1998a)
NigeriaPresent1917Original citation: CABI/EPPO and (1998a)
TanzaniaPresentOriginal citation: CABI/EPPO and (1998a)
TogoPresent1937Original citation: CABI/EPPO and (1998a)

Europe

NetherlandsAbsent, Confirmed absent by survey
SloveniaAbsent

North America

Antigua and BarbudaPresent
BahamasAbsent, Formerly present1946
BelizePresent, Localized1994
Cayman IslandsPresent1834
CubaPresentFirst reported: 192*
Dominican RepublicPresent1915
GuadeloupePresent
GuatemalaPresent
HaitiPresent, Widespread
HondurasPresent, Localized1994
JamaicaPresent1955
MexicoPresent, Localized1978
Netherlands AntillesPresent
Saint Kitts and NevisPresent, Localized
United StatesPresent, Localized1937
-FloridaPresent
-LouisianaPresent, Few occurrences
-TexasAbsent, Unconfirmed presence record(s)

Oceania

AustraliaAbsent, Confirmed absent by survey

South America

GuyanaAbsent, Invalid presence record(s)

Risk of Introduction

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Lethal yellowing and related diseases pose a significant threat to global coconut production (Harries, 1978b). To discourage inadvertent spread of LY in the tropics, commercial movement of living palms and palm seeds from affected to unaffected areas is generally not permitted. However, quarantine requirements vary according to the specific geographic localities involved. Technical guidelines for the safe movement of coconut germplasm from LY-affected areas for research, but not for commercial purposes, have been developed under the auspices of the International Board for Plant Genetic Resources (IBPGR) (Frison et al., 1993).

Hosts/Species Affected

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Historically, decline in a wide variety of palms has been attributed to LY (16SrIV-A), however, most of these records were prior to the advent of molecular diagnostic tools and thus the true identity of the causal agents cannot be stated with confidence due to the diversity of 16SrIV phytoplasmas found throughout the region. While the symptom and SEM data are clear that many of the reported hosts of LY have declined due to phytoplasma infection, the subgroup classification of the majority of hosts cannot be confirmed. The following hosts the putative hosts of the 16SrIV-A phytoplasma; Aiphanes lindeniana (Ruffle palm), Allagoptera arenaria (Kutze seashore palm), Caryota mitis (Burmese or clustering fishtail palm), C. rumphiana (Giant fishtail palm), Chelyocarpus chuco (Round leaf palm), Copernicia alba (Caranday palm), Corypha taliera (Buri palm), Crysophila warsecewiczii (Rootspine palm), Cyphophoenix nucele (Lifou palm), Dypsis cabadae (Cabada palm), D. decaryi (Triangle palm), Gaussia attenuata (Puerto Rican Gaussia palm), Howea belmoreana (Belmore Sentry palm), H. forsteriana (Kentia or Sentry palm), Hyophorbe verschaffeltii (Spindle palm), Latania lontaroides (Latan palm), Livistona chinensis (Chinese fan palm), L. rotundifolia (Footstool palm), Nannorrhops ritchieana (Mazari palm), Phoenix canariensis (Canary Island date palm), P. dactylifera (Date palm), P. reclinata (Senegal date palm), P. rupicola (Cliff date palm), P. sylvestris (Silver date palm), Pritchardia maideniana (Kona palm), P. pacifica (Fiji Island fan palm), P. remota (Remota loulu palm), P. thurstonii (Thurston palm), Ravenea hildebrantii (Hildebrants palm), Syagrus schizophylla (Arikury palm), Veitchia arecina (Montgomerys palm) and Adonidia merrillii (McCoy et al., 1983; Eden-Green, 1997Harrison and Jones, 2004; Harrison and Oropeza, 2008).

The LY phytoplasma (16SrIV-A subgroup) has also been experimentally transmitted to the following palm species: Cocos nucifera, P. canariensis, P. pacifica, P. thurstonii, T. fortunei and A. merrillii. Replicated transmissions to these palm species were achieved using the vector planthopper Haplaxiuscrudus field-collected from palms in areas of high disease incidence in Florida, USA (Howard and Thomas, 1980; Howard et al., 1983). 

Current knowledge of symptomless palm hosts include Thrinax radiata (Florida thatch palm) and Coccothrinax readii (Mexican silver palm) (Narvaez et al., 2006). 

Although restricted primarily to the Arecaceae, the host range of the LY phytoplasma (16SrIV-A) also includes at least one non-palm host, namely the arborescent monocot Pandanus utilis (screwpine) (Thomas and Donselman, 1979; Harrison and Oropeza, 1997). 

The host range of other coconut lethal yellows group (16rIV), subgroup phytoplasmas are as follows: 

16SrIV-B subgroup - Acrocomia aculeata (coyol palm), C. nucifera (Roca et al., 2006); 

16SrIV-C subgroup - C. nucifera (Lee et al., 1998);

16SrIV-D subgroup - Bismarckia nobilis (Bismarck Palm), Carpentaria acuminata (Carpentaria Palm), P. canariensis (Canary Island date palm), P. dactylifera (date palm), P. roebelenii (pygmy date palm), P. sylvestris (silver date palm), Pseudophoenix sargentii (buccaneer palm), Sabal mexicana (Mexican palmetto), Sabal palmetto (cabbage palm), Syagrus romanzoffiana (queen palm) (Harrison et al., 2008, 2009; Rodriguez et al., 2010; Vázquez-Euán et al., 2011);

The host range of 16SrIV-D subgroup phytoplasmas includes the non-palm host Carludovica palmata (Panama hat or jipi palm) (Wei et al., 2007);

16SrIV-E subgroup - C. nucifera (Martinez et al., 2008);

The host range of subgroup 16SrIV-E phytoplasmas includes the non-palm hosts Cleome rutidosperma (fringed spiderflower), Cyanthillium cinereum (little ironweed cited as Vernonia cinerea), Macroptilium lathyroides (wild bushbean), Stachytarpheta jamaicensis (light-blue snakeweed) (Brown et al., 2008; Brown and McLaughlin, 2011).

16SrIV-F subgroup - Washingtonia robusta (Mexican fan palm) (Harrison et al., 2008).

Host Plants and Other Plants Affected

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Plant nameFamilyContextReferences
Adonidia merrillii (Christmas palm)ArecaceaeOther
Aiphanes lindeniana (ruffle palm)ArecaceaeOther
Allagoptera arenaria (Kutze seashore palm)ArecaceaeOther
Arenga engleriArecaceaeOther
Bismarckia nobilisArecaceaeUnknown
Borassus flabellifer (toddy palm)ArecaceaeOther
Brahea brandegeeiArecaceaeUnknown
Caryota mitisArecaceaeOther
Caryota rumphianaArecaceaeOther
Chelyocarpus chuco (round leaf palm)ArecaceaeOther
Chrysalidocarpus cabadaeArecaceaeOther
Coccothrinax readiiArecaceaeUnknown
CocosUnknown
Harrison et al. (2002)
Cocos nucifera (coconut)ArecaceaeMain
Copernicia albaArecaceaeOther
Corypha taliera (Buri palm)ArecaceaeOther
Corypha utan (gebang palm)ArecaceaeOther
Crysophila warsecewiczii (Rootspine palm)ArecaceaeOther
Cyanthillium cinereum (little ironweed)AsteraceaeUnknown
Brown et al. (2008)
Cyphophoenix nucele (Lifou palm)ArecaceaeOther
Dictyosperma albumArecaceaeOther
Dypsis cabadae (Cabada palm)ArecaceaeOther
Dypsis decaryi (triangle palm)ArecaceaeOther
Gaussia attenuata (Puerto Rican Gaussia palm)ArecaceaeOther
Howea belmoreanaArecaceaeOther
Howea forsteriana (paradise palm)ArecaceaeOther
Hyophorbe verschaffeltii (spindle palm)ArecaceaeOther
LataniaArecaceaeOther
Latania lontaroidesArecaceaeOther
Livistona chinensis (Chinese fan palm)ArecaceaeOther
Livistona rotundifoliaArecaceaeOther
Nannorrhops ritchieanaArecaceaeOther
Phoenix canariensis (Canary Island date palm)ArecaceaeOther
Harrison et al. (2008); Harrison et al. (2002)
Phoenix dactylifera (date-palm)ArecaceaeOther
Aviña-Padilla et al. (2011); Harrison et al. (2008)
Phoenix reclinata (senegal date palm)ArecaceaeOther
Phoenix rupicolaArecaceaeOther
Phoenix sylvestris (east Indian wine palm)ArecaceaeOther
Harrison et al. (2008); Ferguson and Singh (2018)
Pritchardia maideniana (Kona palm)ArecaceaeOther
Pritchardia pacificaArecaceaeOther
Pritchardia remota (Remota loula palm)ArecaceaeOther
Pritchardia thurstonii (Thurston palm)ArecaceaeOther
Pseudophoenix sargentiiArecaceaeUnknown
Ravenea hildebrandtii (Hildebrants palm)ArecaceaeOther
Roystonea regia (cuban royal palm)ArecaceaeOther
Sabal mexicanaArecaceaeUnknown
Syagrus romanzoffiana (queen palm)ArecaceaeUnknown
Harrison et al. (2008); Myrie et al. (2014)
Syagrus schizophyllaArecaceaeOther
Thrinax radiataArecaceaeUnknown
Trachycarpus fortunei (chinese windmill palm)ArecaceaeOther
Veitchia arecinaArecaceaeOther
Veitchia macdanielsiiArecaceaeOther
Washingtonia robusta (mexican washington-palm)ArecaceaeUnknown
Wodyetia bifurcata (foxtail palm)ArecaceaeOther

Growth Stages

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Flowering stage, Fruiting stage, Vegetative growing stage

Symptoms

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Palm lethal yellowing disease involves a prolonged latent (incubation), 'asymptomatic’, phase. The time from primary infection to appearance of overt visible symptoms on young, non-bearing coconut palms has been estimated as between 112 and 262 days (Dabek, 1975).

The early stages of LY on coconut palms are accompanied by numerous biochemical and physiological abnormalities in roots that include marked fluctuations in respiration, total sugars and reducing sugars (Oropeza et al., 1995; Islas-Flores et al., 1999; Martínez et al., 2000; Maust et al., 2003). Decreased respiration and increased root necrosis occur prior to the appearance of any visible symptoms in above-ground portions of palms (Eden-Green, 1976, 1982). The onset of symptoms also coincides with alterations in phloem flux rates (Eden-Green and Waters, 1982) and changes in water relations (McDonough and Zimmerman, 1979; Eskafi et al., 1986) due to irreversible suppression of leaf stomatal conductance (Oropeza et al., 1991; León et al., 1996). Reduction of photosynthetic capacity is marked by decreases in photosynthetic pigments, growth regulators and activity of enzymes of the carbon reduction cycle (Dabek and Hunt, 1976; León et al., 1996).

Visible symptoms on the highly susceptible Atlantic tall (also known as Jamaica tall) coconut ecotype chronologically include premature shedding of all fruit (nutfall) regardless of their developmental stage. Aborted nuts often develop a brown-black calyx-end rot reducing seed viability. Premature nutfall is accompanied or followed by inflorescence necrosis. This next symptom is most readily observed as newly mature inflorescences emerge from the ensheathing spathe. Normally light yellow to creamy white in colour, affected inflorescences are instead partially blackened (necrotic) usually at the tips of flower spikelets. As disease progresses, additional emergent or unemerged inflorescences show more extensive necrosis and may be totally discoloured. Such symptom intensification results in the death of most male flowers and an associated lack of fruit set.

Yellowing of the leaves usually starts once necrosis has developed on two or more inflorescences (Arellano and Oropeza, 1995) and discoloration is more rapid than that associated with normal leaf senescence. Beginning with the older (lowermost) leaves, yellowing progresses upward to involve the entire crown. Yellowed leaves turn brown, desiccate and die. In some cases, the advent of this symptom is seen as a single yellow leaf (flag leaf) in the mid-crown. Affected leaves often hang down forming a skirt around the trunk for several days before falling. A putrid basal soft rot of the newly emerged spear (youngest leaf) occurs once foliar yellowing is advanced. Spear leaf collapse and rot of the apical meristem invariably precedes death of the palm at which point the crown topples away leaving a bare trunk. Infected palms usually die within 3 to 6 months after the appearance of the first symptoms (McCoy et al., 1983).

Fruit drop and inflorescence-necrosis are early stage symptoms common to all other palm species affected by LY disease. Differences may occur in the stage at which spear leaf necrosis appears. For edible date palm (Phoenix dactylifera), death of the spear leaf usually precedes foliar discoloration whereas for Adonidia and Veitchia species, the spear is usually unaffected until after all other leaves have died. Two patterns of leaf discoloration have been described. Leaves yellow before dying in species such as fishtail palms (Caryota sp.), round leaf palm (Chelyocarpus chuco), gebang palm (C. elata), fan palms (Livistona and Pritchardia sp.), princess palm (Dictyosperma album) and windmill palm (Trachycarpus fortunei). In most other susceptible species, leaves turn brown rather than yellow. Regardless of species, however, foliar discoloration generally advances from the oldest to youngest leaves in the crown (McCoy et al., 1983).

List of Symptoms/Signs

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SignLife StagesType
Fruit / premature drop
Growing point / rot
Inflorescence / blight; necrosis
Leaves / yellowed or dead

Biology and Ecology

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Transmission

Phytoplasmas are transmitted in a persistent (circulative-propagative) manner primarily by insect vectors belonging to the families Cicadelloidea (leafhoppers) and Fulgoroidea (planthoppers) (D'Arcy and Nault, 1982). The cixiid Haplaxiuscrudus is the putative vector of LY in Florida (Howard et al., 1983, 1984; Eziashi and Omamor, 2010).

Seedborne Aspects

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Incidence

There have been several studies using PCR that have indicated the presence of phytoplasma DNA in embryos of some seed from diseased coconut palms (Harrison et al., 1996; Harrison and Oropeza, 1997; Cordova et al., 2003). A recent study by Oropeza et al. (2011) showed that LY phytoplasma DNA was isolated from embryos of fruits at different stages of development; although the presence of phytoplasma DNA in coconut embryo tissues suggests a potential for seed transmission there is no prior evidence to support seed transmission of LY (Romney, 1983). While detection in embryos is possible, it is important to note that true seed-borne transmission has not been demonstrated so the detection in embryos has little to no epidemiological importance. The majority of fruit is aborted before mature and will not germinate and any mature fruit invaded by the phytoplasma will die before they are desirable for the vector, assuming that infected coconuts will germinate.

Vectors and Intermediate Hosts

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VectorSourceReferenceGroupDistribution
Haplaxius crudusHoward et al. (1983)InsectCaribbean; USA

Impact

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The Atlantic tall, the most prevalent coconut ecotype throughout the Caribbean region and Atlantic coast of the Americas (Harries, 1978a), is highly susceptible to LY disease. During the past three decades, at least 50% of Florida's estimated one million coconut palms and over 80% of Jamaica's five million coconut palms have been eliminated by LY (McCoy et al., 1983). Similar epidemic losses of coconut to LY continued along the Atlantic coasts of southern Mexico and Honduras (Oropeza and Zizumbo, 1997). Although rarely affecting palms less than 5 years old, the disease prevents any re-establishment of highly susceptible coconut ecotypes in LY-endemic locations such as Florida and Jamaica.

Diagnosis

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Phytoplasmas are obligate parasites and cannot be cultured on standard microbial growth media, so identification methods have primarily relied upon visual symptom identification, transmission electron and fluorescent microscopy, and most recently, molecular detection using specific probes for DNA dot hybridization and phytoplasma 'generic' and 'specific' PCR primers followed by restriction fragment analysis or sequencing of the PCR products.

Transmission Electron and Fluorescent Microscopy

In the past, confirmation of field diagnoses had traditionally been based on locating the phytoplasma in palm tissues using transmission electron microscopy (TEM) (Beakbane et al., 1972; Plavsic-Banjac et al., 1972; Thomas and Norris, 1980). Phytoplasmas that are found in the phloem of coconut palms have been described as non-filamentous and filamentous, the previous averaging 295 nm in diameter and the latter averaging 142 nm in diameter and with a length of approximately 16 µm (Waters and Hunt, 1980). The pathogen is found most reliably in young phloem-rich leaf bases surrounding the apical meristem (heart tissues) of symptomatic palms (Thomas 1979; Thomas and Norris, 1980) and to a lesser extent in partially necrotic inflorescences and tertiary roots (Waters and Hunt, 1980). In most mature tissues, phytoplasma concentrations are generally below levels detectable by this diagnostic method.

Phytoplasma infections are characterized by an associated accumulation of DNA within the phloem which can be demonstrated by treatment of either fresh or chemically preserved plant tissues (Seemüller, 1976; Sinclair et al., 1992) with the DNA-binding fluorochrome DAPI (4',6'-diamidino-2-phenylindole, 2HCl). Phytoplasma cells appear as patches of blue-white fluorescence in phloem sieve tube elements of plants such as palms when tissues are examined under UV light by epifluorescence microscopy whereas sieve tubes of healthy palms are devoid of fluorescence and are usually invisible (Cardeña et al., 1991). Although this technique can be used for large scale diagnosis (Andrade and Arismendi, 2013) issues arise due to relatively high levels of false negatives in palms. False negatives are those samples that the phytoplasma titre is extremely low and/or the phytoplasma has accumulated in an uneven pattern throughout the plant.

Both TEM and DAPI detection systems only allow for the 'presence or absence' of phytoplasma within the plant sample, neither can determine the specific strain of phytoplasma that is causing the disease (Harrison et al., 1999).

Molecular Analyses

Molecular detection of the palm lethal yellowing phytoplasma by DNA probe hybridization or PCR assays has largely replaced non-specific microscopic techniques as the preferred methods for disease diagnosis.

Used as probes in DNA dot hybridization assays, DNA fragments of the LY phytoplasma cloned from LY-diseased Manila palm or windmill palm (Harrison et al., 1992; Harrison et al., 1994a; Harrison and Oropeza, 2008) have been used to detect the lethal yellowing phytoplasma and permit detection and identification of the LY phytoplasma, and closely related strains, in extracts derived from palm heart tissues (Harrison et al., 1994b, c; Harrison and Oropeza, 1997; Tymon et al., 1997). However, these probes have also shown to vary in detection sensitivity and specificity (Harrison et al., 2008).

Southern blot hybridization has been used to analyse phytoplasma DNA restriction profiles and can provide a measure of genetic variability among closely related phytoplasma strains (Harrison et al., 1992, 2008).

Polymerase chain reaction (PCR) employing phytoplasma 'universal' primer pairs constructed from 16S ribosomal RNA (rRNA) gene sequences (Lee et al., 1993; Martinez-Soriano et al., 1994; Gundersen and Lee, 1996) has significantly improved phytoplasma detection. These assays readily amplify rDNA of most, or all, phytoplasmas. Digestion of the PCR products with selected restriction enzymes, a process known as restriction fragment length polymorphism (RFLP), provides a DNA fingerprint in the form of 16S rDNA fragment patterns that can be used to determine phytoplasma identity when resolved on agarose or by polyacrylamide gel electrophoresis (PAGE). These primers, however, have also identified non-phytoplasma target sequences. The latter PCR products are similar in size to PCR products from phytoplasmas, so the phytoplasma identity is not known (Harrison et al., 1999). Profiles resolved by PAGE after separate digestion of products with AluI, HinfI, TaqI or Tru9I endonucleases are especially useful for identification of group 16SrIV phytoplasmas (Harrison et al., 1999). They are also useful for distinguishing this pathogen from phytoplasmas associated with African coconut lethal decline diseases (Harrison et al., 1994a) and other recently recognized members of the LY phytoplasma group (Harrison and Oropeza, 1997; Cordova et al., 2000).

Group or subgroup-specific detection of phytoplasmas by utilizing primers for PCR based upon variable regions of the 16S rRNA gene or the 16-23S intergenic spacer region (SR) sequences of the phytoplasma genome permit selective amplification of rRNA gene sequences of 'Ca. Phytoplasma palmae' and related strains in a group-specific manner. Primers 503f and LY16Sr derived from the 16S rRNA gene of the LY phytoplasma selectively amplify a 928 bp rDNA product from the LY phytoplasma strains infecting coconut and Pandanus and from the YLD (Yucatan coconut lethal decline) and CPY (Carludovica palmata yellows) phytoplasmas (Harrison et al., 1999; Cordova et al., 2000). Strains can be further differentiated by AluI digestion of the resulting amplification products.

LY16Sf and LY16Sr also selectively amplify 16SrRNA gene sequences of the LY agent from mixtures with host palm DNA (Harrison and Oropeza, 2008). When used to reamplify products obtained by PCR employing universal primer pair P1 and P7, primer set LY16Sf/LY16Sr amplifies rDNA from the LY phytoplasma and related strains in a group (16SrIV)-specific manner (Harrison et al., 2002a). Polymorphisms revealed by HinfI endonuclease digestion of the rDNA products differentiated coconut-infecting phytoplasmas in Jamaica from those detected in Florida, Honduras and Mexico (Harrison et al., 2002a).

Exclusive detection of 16SrIV-A subgroup strains is possible by a PCR assay employing non-ribosomal primer pair LYF1/LYR1 permitting unequivocal identification of 'Ca. Phytoplasma palmae' (i.e. subgroup 16SrIV-A) in palms, Pandanus utilis, and the vector Haplaxius crudus (Harrison et al., 1994; Llauger et al., 2002).

Analysis of less conserved secA gene sequences has also been used to distinguish groups and subgroups of phytoplasmas (Hodgetts et al., 2008).

PCR allows for sensitive detection of the LY phytoplasma in inflorescence, spear leaf and trunk tissues and has made possible practical non-destructive sampling of palms for LY diagnosis.

Detection and Inspection

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Because of a protracted incubation phase in palms (Dabek, 1975), visual examination for LY symptoms is insufficient to conclusively determine the disease status of palms. To date, no biological or serological tests for detection of the LY phytoplasma have been successfully developed. Currently, qPCR and melt curve analysis are commonly used techniques to detect phytoplasmas in infected palms as well as differentiate sbugroups (Bahder et al., 2017). When symptomless, pre-bearing coconut palms were evaluated for natural infection by LY, monthly assessment of spear leaf samples by LY-specific PCR in a year-long study revealed phytoplasma titres reached detectable levels in these palms between 47 and 57 days prior to the appearance of visible foliar symptoms (Harrison et al., 1994c).

Similarities to Other Species/Conditions

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No single symptom is diagnostic of palm LY disease. Abiotic factors, such as nutritional disorders, may induce premature nutfall (boron deficiency) and foliar discoloration (potassium deficiency). Ganoderma butt rot (Ganoderma zonatum) shows progressive symptoms closely in-line with those of lethal yellowing, such as basal stem rot leading to canopy wilting, die off of lower leaves, and die off of the spear leaf (Broschat et al., 2010). In their advanced stages, coconut lethal declines due to Phytophthora bud rot (Joseph and Radha, 1975; Bennett et al., 1986; Uchida et al., 1992), red ring (Griffith, 1987) and hartrot (Parthasarathy et al., 1978; McCoy and Martinez-Lopez, 1982) all share a number of symptoms in common with LY disease. The geographic ranges of these diseases overlap in some areas of the western Caribbean region and may confuse field diagnoses. The appearance and chronological progression of symptoms (syndrome development) provide accurate identification of LY.

Elsewhere, phytoplasma-associated diseases of coconut resembling LY have been recognized in Nigeria (Awka wilt) (Ekpo and Ojomo, 1990), Ghana (Cape St. Paul wilt), Togo (kaïncopé disease) (Dabek et al., 1976), Cameroon (kribi disease) (Dollet et al., 1977), Tanzania and Kenya (Nienhaus et al., 1982). A previous lack of methods to directly compare the associated aetiological agents led to erroneous speculation about the origins and relatedness of these diseases (Howard, 1983; Maramorosch, 1996). Recent molecular comparisons, with the causative phytoplasmas of these diseases, have since clarified relationships, revealing the LY phytoplasma to be phylogenetically distinct from the African coconut phytoplasmas. Similarly, group 16SrXXII phytoplasma strains affecting coconut in West Africa (Wei et al., 2007) are also distinct from strains associated with coconut lethal disease in Tanzania and Kenya (Tymon et al., 1998; IRPCM Phytoplasma/Spiroplasma Working Team Phytoplasma Taxonomy Group, 2004) but very similar or identical to phytoplasmas affecting coconut in Mozambique (Mpunami et al., 1999; Bonnot et al., 2010).

Still other phylogenetically distinct phytoplasmas have been associated with coconut diseases elsewhere that include Kalimantan wilt in Indonesia (Warokka et al., 2006), coconut yellow decline in Malaysia (Nejat et al., 2009a, b, 2012), coconut (root) wilt (Manimekalai et al., 2010) and yellow leaf disease of Areca catechu (Ramaswamy et al., 2012) in India,Weligma coconut leaf wilt in Sri Lanka (Perera et al., 2012) and Bogia coconut syndrome in Papua New Guinea (Kelly et al., 2011).

Prevention and Control

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Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.

For coconut, the use of genetically resistant ecotypes and hybrids offers the only practical long-term solution to LY given our present understanding of the disease. Both the Malayan dwarf and the Maypan (Malayan dwarf x Panama tall) hybrid were thought to be resistant to LY and were used extensively for replanting in Jamaica and other countries affected by the disease. However, high mortality in both cultivars planted in LY-infected regions in recent years shows that these cultivars cannot be considered resistant to LY as previously thought (Broschat et al., 2002; Lebrun et al., 2008). Other hybrids have also succumbed to lethal yellowing disease in other countries, such as Ghana, where there was extensive planting of the hybrid Malayan Yellow Dwarf x Vanatu Tall (MYD x VTT) which were used to replace palms that had succumbed to Cape Saint Paul Wilt of coconuts (Danyo and Dery, 2011; Danyo, 2011). Promising levels of resistance have been identified in other ecotypes such as Chowghat green dwarf, Cuban dwarf, Fiji dwarf, Red spicata dwarf, Sri Lanka yellow dwarf and King, but this resistance remains to be commercially exploited (Harries, 1995; Ashburner and Been, 1997).  

In contrast to coconut, useful varietal resistance to LY in the commercially important edible date palm (Phoenix dactylifera) has not been demonstrated (Howard, 1992). With the exception of species of Pritchardia (Howard and Barrant, 1989), the relative susceptibility to LY of all remaining host palms, while varying among species, is generally lower than that of coconut palm (McCoy et al., 1983; Meerow, 1992). Numerous popular ornamental palm species are apparent non-hosts of LY and are recommended for landscape and amenity plantings in affected areas (Chase and Broschat, 1991; Meerow, 1992).

Eradication of infected palms does not lead to any measurable reduction in the spread of LY in highly susceptible coconut ecotype populations in newly affected areas. A reduction in the rate of spread of disease has been demonstrated by insecticide suppression of vector Haplaxius crudus populations (Howard and McCoy, 1980). Identified as poor breeding hosts of H. crudus, tropical forage grasses such as Brachiara brizantha, Chloris gayana or Hemarthria altissima used as groundcovers underlying palms provide an additional promising means of controlling vector abundance (Howard, 1989, 1990). Oxytetracycline-HCl (OTC), a systemic antibiotic treatment that is injected into the palm trunk on a quarterly basis, can be effective but they are not economical in large-scale nursery settings or coconut-producing regions (McCoy et al., 1976). However, in landscape and amenity plantings, this control measure can be utilized to control early stage symptoms of infection and can be used as a preventative treatment in healthy palms (Hunt et al., 1974; McCoy et al., 1982).

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Manimekalai R, Soumya VP, Kumar RS, Selvarajan R, Reddy K, Thomas GV, Sasikala M, Rajeev G, Baranwal VK, 2010. Molecular detection of 16SrXI group phytoplasma associated with root (wilt) disease of coconut (Cocos nucifera) in India. Plant Disease, 94(5):636. http://apsjournals.apsnet.org/loi/pdis

Maramorosch K, 1996. Lethal yellowing disease of palms. In: Raychaudhuri SP, Maramorosch K, eds, Forest Trees and Palms, Diseases and Control. New Delhi, India: Oxford & IBH Publishing Co. PVT. LTD, 253-265

Martinez RT, Narvaez M, Fabre S, Harrison N, Oropeza C, Dollet M, Hichez E, 2008. Coconut lethal yellowing on the southern coast of the Dominican Republic is associated with a new 16SrIV group phytoplasma. Plant Pathology, 57(2):366. http://www.blackwell-synergy.com/doi/full/10.1111/j.1365-3059.2007.01726.x

Martinez S, Cordova I, Maust BE, Oropeza C, Santamaria JM, 2000. Is abscisic acid responsible for abnormal stomatal closure in coconut palms showing lethal yellowing? Journal of Plant Physiology, 156(3):319-322

Martinez-Soriano JP, Alymeda-Leon IH, Pina-Razo J, Rocha-Pena MA, Byerly-Murphy KF, 1994. Detection of Phytoplasma sp. asssociated with lethal yellowing of coconut palms using polymerase chain reaction. Revista Mexicana de Fitopatologia, 12:75-79

Maust BE, Espadas F, Talavera C, Aguilar M, Santamaría JM, Oropeza C, 2003. Changes in carbohydrate metabolism in coconut palms infected with the lethal yellowing phytoplasma. Phytopathology, 93(8):976-981

McCoy RE, 1976. Comparative epidemiology of the lethal yellowing, Kaincope, and cadang-cadang diseases of coconut palm. Plant Disease Reporter, 60(6):498-502

McCoy RE, Carroll VJ, Poucher CP, Gwin GH, 1976. Field control of coconut lethal yellowing with oxytetracycline hydrochloride. Phytopathology, 66(9):1148-1150

McCoy RE, Howard FW, Tsai JH, Donselman HM, Thomas DL, Basham HG, Atilano RA, Eskafi FM, Britt L, Collins ME, 1983. Lethal yellowing of palms. University of Florida Agricultural Experiment Station Bulletin No. 834

McCoy RE, Martinez-Lopez G, 1982. Phytomonas staheli associated with coconut and oil palm diseases in Colombia. Plant Disease, 66(8):675-677

McCoy RE, Miller ME, Williams DS, 1980. Lethal yellowing in Texas Phoenix palms. Principes, 24(4):179-180

McCoy RE, Norris RC, Vieyra G, Delgado S, 1982. Lethal yellowing disease of coconut palms. FAO Plant Protection Bulletin, 30(2):79-80

McDonough J, Zimmerman MH, 1979. Effect of lethal yellowing on xylem pressure in coconut palms. Principes, 23(3):132-137

Meerow, AW, 1992. Betrock's Guide to Landscape Palms. Cooper City, Florida, USA: Betrock Information Systems, Inc

Mpunami AA, Tymon A, Jones P, Dickinson MJ, 1999. Genetic diversity in the coconut lethal yellowing disease phytoplasmas of East Africa. Plant Pathology, 48(1):109-114

Murray RGE, Schleifer KH, 1994. Taxonomic notes: a proposal for recording the properties of putative taxa of procaryotes. International Journal of Systematic Bacteriology, 44:174-176

Myrie WA, Douglas L, Harrison NA, McLaughlin W, James M, 2012. First report of lethal yellowing disease associated with subgroup 16SrIV, a phytoplasma on St. Kitts in the Lesser Antilles. New Disease Reports, 26:25. http://www.ndrs.org.uk/article.php?id=026025

Myrie WA, Harrison NA, Douglas L, Helmick E, Gore-Francis J, Oropeza C, McLaughlin WA, 2014. First report of lethal yellowing disease associated with subgroup 16SrIV-A phytoplasmas in Antigua, West Indies. New Disease Reports, 29:12. http://www.ndrs.org.uk/article.php?id=029012

Narvaez M, Cordova I, Orellana R, Harrison NA, Oropeza C, 2006. First report of a lethal yellowing phytoplasma in Thrinax radiata and Coccothrinax readii palms in the Yucatan Peninsula of Mexico. Plant Pathology, 55(2):292

Nejat N, Sijam K, Abdullah SNA, Vadamalai G, Dickinson M, 2009. Molecular characterization of a phytoplasma associated with Coconut Yellow Decline (CYD) in Malaysia. American Journal of Applied Sciences, 6(7):1331-1340. http://www.scipub.org/fulltext/ajas/ajas671331-1340.pdf

Nejat N, Sijam K, Abdullah SNA, Vadamalai G, Dickinson M, 2009. Phytoplasmas associated with disease of coconut in Malaysia: phylogenetic groups and host plant species. Plant Pathology, 58(6):1152-1160. http://www.blackwell-synergy.com/loi/ppa

Nejat N, Vadamalai G, Davis RE, Harrison NA, Sijam K, Dickinson M, Nor S, Abdullah A, Zhao Y, 2012. 'Candidatus Phytoplasma malaysianum', a novel taxon associated with virescence and phyllody of Madagascar periwinkle (Catharanthus roseus). International Journal of Systematic and Evolutionary Microbiology

Nienhaus F, Schuiling M, Gliem G, Schinzer U, Spittel A, 1982. Investigations on the etiology of the lethal disease of coconut palm in Tanzania. Zeitschrift fur Pflanzenkrankheiten und Pflanzenschutz, 89(4):185-193

Nipah, J. O., Jones, P., Hodgetts, J., Dickinson, M., 2007. Detection of phytoplasma DNA in embryos from coconut palms in Ghana, and kernels from maize in Peru. Bulletin of Insectology, 60(2), 385-386. http://www.bulletinofinsectology.org/

Oropeza C, Alpizar L, Islas-Flores I, Escamilla A, Santamarfa J, 1995. Physiology and biochemistry of lethal yellowing-affected Cocos nucifera L. palms In: Oropeza C, Howard FW, Ashburner GR, eds. Lethal Yellowing: Research and Practical Aspects. Dordrecht, Netherlands: Kluwer Academic Publishers, 65-77

Oropeza C, Cordova I, Chumba A, Narváez M, Sáenz L, Ashburner R, Harrison N, 2011. Phytoplasma distribution in coconut palms affected by lethal yellowing disease. Annals of Applied Biology, 159(1):109-117. http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1744-7348

Oropeza C, Zizumbo D, 1997. A history of lethal yellowing in Mexico. In: Eden-Green SJ, Ofori F, eds, Proceedings of an International Workshop on Lethal Yellowing-Like Diseases of Coconut, Elmina Ghana, November 1995. United Kingdom: Natural Resources Institute, 69-76

Oropeza CM, Santamarfa JM, Villaneuva MA, Loyola-Vargas VM, 1991. Physiology and biochemistry of lethal yellowing in Cocos nucifera. Principes, 35:208-218

Parthasarathy MV, Slobbe WGVan, 1978. Hartrot or fatal wilt of palms I. Coconuts (Cocos nucifera). Principes, 22(1):3-14

Perera L, Meegahakumbura MK, Wijesekara HRT, Fernando WBS, Dickinson MJ, 2012. A phytoplasma is associated with the Weligama coconut leaf wilt disease in Sri Lanka. Journal of Plant Pathology, 94(1):205-209. http://sipav.org/main/jpp/index.php/jpp/article/view/2456

Plavsic-Banjac B, Hunt P, Maramorosch K, 1972. Mycoplasmalike bodies associated with lethal yellowing disease of coconut palms. Phytopathology, 62:298-299

Poghosyan, A., Henandez-Gonzalez, J., Lebsky, V., Oropeza, C., Narvaez, M., Leon de La Luz, J. L., 2019. First report of 16SrIV palm lethal yellowing group phytoplasma (‘Candidatus Phytoplasma palmae’) in palmilla de taco (Brahea brandegeei) and palma colorada (Washingtonia robusta) in the state of Baja California Sur, Mexico. Plant Disease, doi: 10.1094/PDIS-02-19-0247-PDN

ProMED-mail, 2012. Lethal yellowing, coconut palm-Antigua. Lethal yellowing, coconut palm-Antigua, Fri 27 Jul 2012: 20120801.1223614. http://www.promedmail.org

Ramaswamy M, Nair S, Soumya VP, Thomas GV, 2012. Phylogenetic analysis identifies 'Candidatus Phytoplasma oryzae'-related strain associated with Yellow Leaf Disease of Areca palm (Areca catechu L.) in India. International Journal of Systematic and Evolutionary Microbiology

Rey M(Coordinator), 1978. Third meeting of the International Council on Lethal Yellowing, FL-78-2. Fort Lauderdale, USA: Agricultural Research Center., 43 pp

Roca MM, Castillo MG, Harrison NA, Oropeza C, 2006. First report of a 16SrIV group phytoplasma associated with declining coyol palms in Honduras. Plant Disease, 90(4):526

Rodriguez JV, Vitoreli AM, Ramirez AL, 2010. Association of a phytoplasma with dieback in palms in Puerto Rico confirmed by nested-PCR assays. Phytopathology, 100(6):S110

Romney DH, 1983. Brief review of coconut lethal yellowing. Indian Coconut Journal, 13:1-8

Sears BB, Kirkpatrick BC, 1994. Unveiling the evolutionary relationships of plant-pathogenic mycoplasmalike organisms. Phylogenetic insights may provide the key to culturing phytoplasmas. ASM News (Washington), 60(6):307-312

Seemnller E, Marcone C, Lauer U, Ragozzino A, G÷schl M, 1998. Current status of molecular classification of the phytoplasmas. Journal of Plant Pathology, 80:3-26

Seemüller E, 1976. Demonstration of mycoplasma-like organisms in the phloem of trees with pear decline or proliferation symptoms by fluorescence microscopy. Phytopatholigische Zeitschrift, 85:368-372

Seemüller E, Schneider B, Maürer R, Ahrens U, Daire X, Kison H, Lorenz KH, Firrao G, Avinent L, Sears BB, Stackebrandt E, 1994. Phylogenetic classification of phytopathogenic mollicutes by sequence analysis of 16S ribosomal DNA. International Journal of Systematic Bacteriology, 44(3):440-446

Sinclair WA, Griffiths HM, Davis RE, Lee IM, 1992. Detection of ash yellows mycoplasmalike organisms in different tree organs and in chemically preserved specimens by a DNA probe vs. DAPI. Plant Disease, 76(2):154-158

Thomas DL, 1979. Mycoplasmalike bodies associated with lethal declines of palms in Florida. Phytopathology, 69(9):928-934

Thomas DL, Donselman HM, 1979. Mycoplasmalike bodies and phloem degeneration associated with declining Pandanus in Florida. Plant Disease Reporter, 63(11):911-916

Thomas DL, Howard FW, Donselman HM, 1980. Fourth Meeting of the International Council on Lethal Yellowing: Proceedings, Fort Lauderdale, Florida, August 13-17, 1979. Gainesville, USA: Agricultural Research Center, Institute of Food and Agricultural Sciences, University of Florida for the International Council on Lethal Yellowing, 22 pp, 22 pp

Thomas DL, Norris RC, 1980. The use of electron microscopy for lethal yellowing diagnosis. Proceedings of the Florida State Horticultural Society, 93:196-199

Tymon AM, Jones P, Harrison NA, 1997. Detection and differentiation of African coconut phytoplasmas: RFLP analysis of PCR-amplified 16S rDNA and DNA hybridisation. Annals of Applied Biology, 131(1):91-102; 46 ref

Tymon AM, Jones P, Harrison NA, 1998. Phylogenetic relationships of coconut phytoplasmas and the development of specific oligonucleotide PCR primers. Annals of Applied Biology, 132(3):437-452; 41 ref

Uchida JY, Aragaki M, Ooka JJ, Nagata NM, 1992. Phytophthora fruit and heart rots of coconut in Hawaii. Plant Disease, 76(9):925-927

US Fish and Wildlife Service, 2008. Pritchardia kaalae (Lo'ulu). 5-Year Review: Summary and Evaluation. In: Pritchardia kaalae (Lo'ulu). 5-Year Review: Summary and Evaluation : US Fish and Wildlife Service.11 pp.

US Fish and Wildlife Service, 2009. 5-Year Review, Short Form Summary: Species Reviewed: Pritchardia schattaueri (Lo`ulu). In: 5-Year Review, Short Form Summary: Species Reviewed: Pritchardia schattaueri (Lo`ulu) : US Fish and Wildlife Service.7 pp.

Vázquez-Euán R, Harrison N, Narvaez M, Oropeza C, 2011. Occurrence of a 16SrIV group phytoplasma not previously associated with palm species in Yucatan, Mexico. Plant Disease, 95(3):256-262. http://apsjournals.apsnet.org/loi/pdis

Warokka JS, Jones P, Dickinson MJ, 2006. Detection of phytoplasmas associated with Kalimantan wilt disease of coconut by the polymerase chain reaction. Jurnal Littri, 12(4):154 - 160

Waters H, Hunt P, 1980. The in vivo three-dimensional form of a plant mycoplasma-like organism by the analysis of serial ultrathin sections. Journal of General Microbiology, 116(1):111-131

Wei Wei, Davis RE, Lee IngMing, Zhao Van, 2007. Computer-simulated RFLP analysis of 16s rRNA genes: identification of ten new phytoplasma groups. International Journal of Systematic and Evolutionary Microbiology, 57(8):1855-1867. http://ijs.sgmjournals.org

White DT, Blackall LL, Scott PT, Walsh KB, 1998. Phylogenetic positions of phytoplasmas associated with dieback, yellow crinkle and mosaic diseases of papaya, and their proposed inclusion in 'Candidatus Phytoplasma australiense' and a new taxon, 'Candidatus Phytoplasma australasia'. International Journal of Systematic Bacteriology, 48(3/4):941-951; 46 ref

Zhao Y, Wei W, Lee IM, Shao J, Suo XB, Davis RE, 2009. Construction of an interactive online phytoplasma classification tool, iPhyClassifier, and its application in analysis of the peach X-disease phytoplasma group (16SrIII). International Journal of Systematic and Evolutionary Microbiology, 59(10):2582-2593. http://ijs.sgmjournals.org

Zreik L, Carle P, Bove JM, Garnier M, 1995. Characterization of the mycoplasmalike organism associated with witches'-broom disease of lime and proposition of a Candidatus taxon for the organism, "Candidatus Phytoplasma aurantifolia". International Journal of Systematic Bacteriology, 45(3):449-453

Zwolińska, A., Krawczyk, K., Pospieszny, H., 2012. Molecular characterization of stolbur phytoplasma associated with pea plants in Poland. Journal of Phytopathology, 160(7/8), 317-323. doi: 10.1111/j.1439-0434.2012.01903.x

Distribution References

Ashburner G R, Córdova I I, Oropeza C M, Illingworth R, Harrison N A, 1996. First report of coconut lethal yellowing disease in Honduras. Plant Disease. 80 (8), 960. DOI:10.1094/PD-80-0960C

Aviña-Padilla K, Rodríguez-Páez L A, Nava-Castrejón Á I, Ochoa-Sánchez J C, Rivera-Bustamante R, Martínez-Soriano J P, 2011. Epidemic of lethal yellowing disease affecting Phoenix dactilyfera and Sabal mexicana in central Mexico. Bulletin of Insectology. 64 (Supplement), S221-S222. http://www.bulletinofinsectology.org/

Broschat T K, Harrison N A, Donselman H, 2002. Losses to lethal yellowing cast doubt on coconut cultivar resistance. Palms. 46 (4), 185-189.

Brown S E, Been B O, McLaughlin W A, 2006. Detection and variability of the lethal yellowing group (16Sr IV) phytoplasmas in the Cedusa sp. (Hemiptera: Auchenorrhyncha: Derbidae) in Jamaica. Annals of Applied Biology. 149 (1), 53-62. http://www.blackwell-synergy.com/doi/pdf/10.1111/j.1744-7348.2006.00072.x DOI:10.1111/j.1744-7348.2006.00072.x

Brown S E, Been B O, McLaughlin W A, 2008. First report of lethal yellowing group (16Sr IV) of phytoplasmas in Vernonia cinerea in Jamaica. Plant Disease. 92 (7), 1132. HTTP://www.apsnet.org DOI:10.1094/PDIS-92-7-1132A

Brown S E, McLaughlin W A, 2011. Identification of lethal yellowing group (16SrIV) of phytoplasmas in the weeds Stachytarpheta jamaicensis, macroptilium lathyroides and cleome rutidosperma in Jamaica. Phytopathogenic Mollicutes. 1 (1), 27-34. DOI:10.5958/j.2249-4669.1.1.004

CABI, Undated. Compendium record. Wallingford, UK: CABI

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Escamilla JA, Harrison NA, Alpizar L, Oropeza C, 1993. Detection of lethal yellowing mycoplasmalike organisms by DNA probes in Yucatán, México. In: Advances in Coconut Research and Development, [ed. by Nair MK, Khan HH, Gopalasundaram P, Bhaskara Rao]. New Delhi, India: Oxford & IBH Publishing Co. PVT. LTD. 597-604.

Ferguson M H, Singh R, 2018. First report of lethal yellowing associated with phytoplasma subgroup 16SrIV-A on silver date palm and Chinese windmill palm in Louisiana. Plant Disease. 102 (10), 2028. DOI:10.1094/PDIS-11-17-1729-PDN

Harrison N A, Helmick E E, Elliott M L, 2008. Lethal yellowing-type diseases of palms associated with phytoplasmas newly identified in Florida, USA. Annals of Applied Biology. 153 (1), 85-94. http://www.blackwell-synergy.com/loi/aab DOI:10.1111/j.1744-7348.2008.00240.x

Harrison N A, Narváez M, Almeyda H, Cordova I, Carpio M L, Oropeza C, 2002a. First report of group 16SrIV phytoplasmas infecting coconut palms with leaf yellowing symptoms on the Pacific coast of Mexico. Plant Pathology. 51 (6), 808. DOI:10.1046/j.1365-3059.2002.00778.x

Harrison N A, Womack M, Carpio M L, 2002. Detection and characterization of a lethal yellowing (16SrIV) group phytoplasma in Canary Island date palms affected by lethal decline in Texas. Plant Disease. 86 (6), 676-681. DOI:10.1094/PDIS.2002.86.6.676

IPPC, 2012. Detection of Lethal Yellowing in St. Kitts and Nevis. In: IPPC Official Pest Report, No. KNA-05/1, No. KNA-05/1, Rome, Italy: FAO. https://www.ippc.int/

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McCoy R E, Miller M E, Williams D S, 1980. Lethal yellowing in Texas Phoenix palms. Principes. 24 (4), 179-180.

Myrie W A, Douglas L, Harrison N A, McLaughlin W, James M, 2012. First report of lethal yellowing disease associated with subgroup 16SrIV, a phytoplasma on St. Kitts in the Lesser Antilles. New Disease Reports. 25. http://www.ndrs.org.uk/article.php?id=026025 DOI:10.5197/j.2044-0588.2012.026.025

Myrie W A, Harrison N A, Douglas L, Helmick E, Gore-Francis J, Oropeza C, McLaughlin W A, 2014. First report of lethal yellowing disease associated with subgroup 16SrIV-A phytoplasmas in Antigua, West Indies. New Disease Reports. 12. http://www.ndrs.org.uk/article.php?id=029012 DOI:10.5197/j.2044-0588.2014.029.012

Myrie W A, Paulraj L, Dollet M, Wray D, Been B O, McLaughlin W, 2006. First report of Lethal yellowing disease of coconut palms caused by phytoplasma on Nevis Island. Plant Disease. 90 (6), 834. DOI:10.1094/PD-90-0834A

Narvaez M, Cordova I, Orellana R, Harrison N A, Oropeza C, 2006. First report of a lethal yellowing phytoplasma in Thrinax radiata and Coccothrinax readii palms in the Yucatan Peninsula of Mexico. Plant Pathology. 55 (2), 292. DOI:10.1111/j.1365-3059.2005.01306.x

Narváez M, Vázquez-Euán R, Harrison N A, Nic-Matos G, Julia J F, Dzido J L, Fabre S, Dollet M, Oropeza C, 2018. Presence of 16SrIV phytoplasmas of subgroups A, D and E in planthopper Haplaxius crudus Van Duzee insects in Yucatán, Mexico. 3 Biotech. 8 (1), 61. DOI:10.1007/s13205-018-1094-5

Nipah J O, Jones P, Hodgetts J, Dickinson M, 2007. Detection of phytoplasma DNA in embryos from coconut palms in Ghana, and kernels from maize in Peru. Bulletin of Insectology. 60 (2), 385-386. http://www.bulletinofinsectology.org/

NPPO of the Netherlands, 2013. Pest status of harmful organisms in the Netherlands., Wageningen, Netherlands:

PLAVSIC-BANJAC B, HUNT P, MARAMOROSCH K, 1972. Mycoplasmalike bodies associated with lethal yellowing disease of coconut palms. Phytopathology. 62 (2), 298-299. DOI:10.1094/Phyto-62-298

Poghosyan A, Henandez-Gonzalez J, Lebsky V, Oropeza C, Narvaez M, Leon de La Luz J L, 2019. First report of 16SrIV palm lethal yellowing group phytoplasma (‘Candidatus Phytoplasma palmae’) in palmilla de taco (Brahea brandegeei) and palma colorada (Washingtonia robusta) in the state of Baja California Sur, Mexico. Plant Disease. DOI:10.1094/PDIS-02-19-0247-PDN

Thomas D L, 1979. Mycoplasmalike bodies associated with lethal declines of palms in Florida. Phytopathology. 69 (9), 928-934. DOI:10.1094/Phyto-69-928

Vázquez-Euán R, Harrison N, Narvaez M, Oropeza C, 2011. Occurrence of a 16SrIV group phytoplasma not previously associated with palm species in Yucatan, Mexico. Plant Disease. 95 (3), 256-262. http://apsjournals.apsnet.org/loi/pdis DOI:10.1094/PDIS-02-10-0150

Zwolińska A, Krawczyk K, Pospieszny H, 2012. Molecular characterization of stolbur phytoplasma associated with pea plants in Poland. Journal of Phytopathology. 160 (7/8), 317-323. http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1439-0434 DOI:10.1111/j.1439-0434.2012.01903.x

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12/12/12 Review by:

Nigel A Harrison, University of Florida, Plant Pathology Dept., FLREC 3205 College Avenue, Fort Lauderdale, FL 33314, USA

 

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