McCoy and Martinez-Lopez, 1982). Some investigators suspect
the vector of hartrot to be a plant bug of the Pentatomid family
(Griffith, 1981). However, this author suggests that a leafhopper
may be involved because the limitation of the flagellates to sieve
tubes suggests the vector to be a phloem feeding insect. In sup-
port of this hypothesis it was shown that another flagellate, P.
davidi, could multiply to high titers within a leafhopper known
to be a vector of several MLO diseases (McCoy and Markham,
1983).


Red Ring
 Red ring disease is another systemic, fatal malady of coconut
palm in the Caribbean region. Foliar symptoms are somewhat
non-specific, but a discoloration and drooping of the leaves
usually occurs in association with rotting of the bud and roots.
Fruit on RR diseased palms is often retained, and the time from
initial symptoms till death of the palm averages four months.
However, the definitive visual symptom of RR is the presence of a
brick-red ring of discolored tissue some 5 to 10 cm beneath the
outer layer of the stem and extending more or less the length of
the stem. The discoloration may extend into the older leaf
petioles as well.
 Red ring disease is caused by the nematode Rhadinaphelinchus
cocophilus (Dean, 1979). This long slender nematode invades
ground tissues of the stem, and may be observed when infected
tissue samples are placed in a petri dish with water for several
hours to overnight. The nematodes may be lifted from the water
with the aid of a dissecting microscope and a sharpened bamboo
sliver, and placed on a microscope slide for observation at higher
magnification. C.G. Dean (1979) gives an excellent description
of the nematodes. The RR nematode is transmitted from palm to
palm by the black palm weevil Rhynchophoruspalmarum. Adult
weevils emerging from infected palms are infested with the
nematode, and serve to carry the pathogen to nearby healthy
palms.
 Diagnosis of RR is based, in part, on the field symptom of the
red ring which can be observed by cutting a notch into the base of
the palm with a machete or axe. However, a definitive diagnosis
is dependent on the recovery and identification of the nematode
R. cocophilus.


Budrot
 Budrot, caused by the fungus Phytophthorapalmivora appears
to be of minor importance, causing small losses of palms
throughout the region. Budrot is characterized by the collapse of
the youngest leaves in the crown, followed by a putrid rot of the
growing point. Developing fruit are retained and the older leaves
may remain green for up to a year after loss of the whorl of
younger leaves.
 Diagnosis of budrot is primarily by symptomatology. Isolations
of Phytophthora may be made from bud tissues distant from the
secondary rot that invariably occurs in the meristematic region.
The occurrence of palm weevils in the bud may produce symp-
toms that mimic budrot, as may a nearby lightning strike.


Buttrot
 Buttrot is another lethal disease of coconut palm that is con-
 sidered to be of overall minor importance. Buttrot is caused by in-
 vasion of the base of older palms by the fungus Ganoderma.
 Dark colored, fungal brackets may be seen at the base of 20- to
 40-year old infected palms. Infected palms decline and die slowly
 with a slow tapering off of growth. The fungal brackets are con-
 sidered diagnostic. Infection by Ganoderma usually, occurs
 through soil.


Stem Bleeding
 Stem bleeding disease has been reported from most areas of the
Caribbean Basin. This disease is caused by the fungus Ceratocystis
(Thielaviopsis) paradox. As its name implies, stem bleeding is
characterized by a soft rotting of the internal tissues of the stem
and the copious oozing of sap outside of the stem. Diagnosis
should be confirmed by isolation of the causal fungus, as lightning
strike and trunk borers will also cause bleeding of the stem.


Lightning Strike
 Coconut palms are apparently good conductors of electricity, as
annually up to 1% loss may be expected from lightning strikes.
Symptoms of lightning strike are an almost immediate collapse of
foliage with discoloration to a watersoaked green, followed by
dessication. Fruit is generally retained and the stem will become
discolored from the copious bleeding of rust brown sap. Occa-
sionally a grazing strike or the strike of a nearby tree will cause the
death of the younger whorl of leaves with an ensuing budrot that
will mimic the budrot disease caused by Phytophthora.
 A related, though not fatal, problem is power line burn which
occurs on palms grown adjacent to a power line. Fronds blown in-
to contact with wires by the wind will be burned by electricity arc-
ing to the leaves. Leaves adjacent to power lines are usually brown
and dessicated at the tips, and extensively yellowed at the base.


Bronze Leaf Wilt
 Bronze leaf wilt is a problem on hardpan soils in certain
regions. It is apparently a physiological problem related to lack of
moisture in the dry season, followed by waterlogging during the
rainy season (Griffith, 1981). The literature concerning this syn-
drome is particularly confusing since the name has been used
interchangeably with Cedros wilt (hartrot) prior to the discovery
of flagellates in palms affected by the latter disease. Bronze leaf
wilt is not necessarily a fatal problem and affected palms usually
recover fully (Griffith, 1981).


Geographic Distribution
 The distribution of these lethal diseases of coconut palm,
within and surrounding the Caribbean Basin, is not uniform
(Fig. 1). Lethal yellowing occurs in and to the north ofJamaica,
through Cuba, and into Florida. LY extends from Grand Bahama
on the east, to the Rio Grande Valley of Texas (where it affects
date palms), with a further outbreak on the eastern coast of the
Yucatan Peninsula (McCoy [ed.], 1983; McCoy et al., 1980).
Currently LY is spreading rapidly in the state of Quintana Roo,
Mexico. LY has been reported from the island of Hispanola but
has not been observed there in recent times (Howard et al.,
1981). LY is also notably absent from many of the Bahama
Islands, Puerto Rico, and the Lesser Antilles. LY has not been
reported from Central or South America.
 Hartrot disease has been reported in most of northern South
America, and from Central America (Dollet et al., 1977; Grif-
fith, 1981; McCoy and Martinez-Lopez, 1982; Parthasarathy et
al., 1976; Waters, 1978). HR is not known to overlap areas where
LY has occurred. Red ring is found in most areas where HR occurs
and as far north as Quintana Roo, Mexico where it may be found
in the same locality as LY (McCoy et al., 1980). The bronze leaf
wilt disease has been reported from Trinidad and Venezuela
(Griffith, 1981). The diseases budrot, buttrot, and stem bleeding
have been reported from most areas where coconut is grown,
albeit usually in low numbers of palms affected. As mentioned, a
number of these syndromes may be confused with the symptoms
of lightning strike and it is possible that many of the reports of
these diseases may actually have been due to lightning.


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