Control of Hartrot or Fatal Wilt of Coconut Palm

 V. T. Alexander P. Kastelein
 P.O.B. 160, Palm Research Center
 Ministry of Agriculture
 Paramaribo, Suriname, South America


 Hartrot, or fatal wilt of coconut considered to be caused by
the constant association of flagellate Phytomonas in the
phloem of the diseased palm, is a potential danger affecting
the progress of the economically important palm culture in
Suriname and this region. In our attempts to control the
disease, the results of field experiments revealed that
periodical application of the insecticide Endrin around the
coconut palms and weed control in the coconut plantations,
checks the rapid spread of the disease. These indications on a


practical scale proved that the same Endrin treatment applied
only to the surrounding trees of a diseased palm, after killing
the affected palm as soon as initial symptoms are noticed, and
weed control in plantations where the disease was endemic
checks this disease more or less on a permanent basis after
about nine months of commencement of the treatment.
Keywords: Coconut; hartrot; fatal wilt; flagellates;
Phytomonas; control.


 Hartrot or fatal wilt of coconut was first recorded in Suriname
by Drost (1908). This disease has been observed in both
economically important coconut and oil palms.. Now it is
widespread in South America and the Caribbean Region. In
1976, Parthasarathy et al. identified the flagellate Phytomonas in
the phloem of the diseased coconut palm. Since then the cons-
tant association of these flagellates with this disease has been well
established.
 This disease is characterized in coconuts by the yellowing of
leaves starting from the oldest and then progressively affecting
the younger ones. This is followed by dropping nuts; the im-
mature ones fall initially and are followed by the mature ones.
The next phase is a blackening of female flowers and browning of
the younger inflorescences. Finally, a rot of the spear takes place
and the spear leaf topples over emitting a foul smell. The apical
region also rots with a similar odour. The course of the disease,
from initial symptoms to the complete death of the plant, takes
place in a period of 6 to 12 weeks. There is no recorded case of
recovery after the initial symptoms occur. This disease has poten-
tial for rapid spread which endangers the palm industry of South
America and the Caribbean.
 From research, mainly on applied aspects conducted in
Suriname for the last few years, we are able to identify preventive
measures to control the rapid spread of the disease in coconut
plantations. These measures have also been successfully extended
to farmers' fields. The basic aspects of the disease still remain to
be fully investigated.


MATERIALS AND METHODS
 Four different trials were conducted in experimental stations,
 two of them with different chemicals and the other two by con-
 trolling weeds. On a practical scale, trials were conducted in four
 different locations, three of them in experimental fields and one
 in a private farmer's holding.


 Chemical Trials
 The first trial in La Poule (PO 86), Endrin, Furadan and
 Chestnut compound were used. The second trial in Jenny (VP
 548), Endrin and Sevin were used.


42


 Endrin 20% was applied at the rate of 80cc in 5 to 10 litres of
water once in two months to wet the soil around the base of the
tree in a circle whose circumference was m for the tree.
 Furadan 5% granule, at a dose of 280g per tree, was applied
once in four months to the soil around the base of the tree in a
circle whose circumference was im for the tree.
 Thirty grams of Chestnut compound was dissolved in a little
hot water and a solution was made with 9 litres of cold water and
used as a soil drench. This was also applied once in four months.
Sevin 85 %, at a rate of 6g per litre of water per palm, was sprayed
on the crown once in three months.
 Untreated palms were included in both experiments which
were laid out in a randomized block design. The treatments were
replicated six and five times in the first and second experiments,
respectively. The first trial commenced during May 1979, and
after 20 months of experimentation the results were analysed.
The second experiment was started in October 1979 and ended in
March 1983 when the results were reviewed.


Weed Control Trials
 The first trial in La Poule (PO 86) was started in May 1979, and
the results were checked after 20 months. The second in Jenny
(VP 599) started in May 1980, and the results were analysed at
completion in September 1983.
 Weed control was done either by hand or herbicides whenever
necessary to keep the area completely free of weeds. In non-
weeded control plots, only the tree circle was kept free of weeds.
 In the four trials on a practical scale, the first in Brokobaka (BR
18) was conducted in 1979, the second in Coebiti (CO 40) in
1981, the third in a private field at Uitkijkpolder (VP 609) in
February 1983, and the fourth in Jarikaba (VP 596) in August
1983.
 Regular observation for disease was made in all trials. In the
first two, application of Endrin was done as a soil drench around
the base of hartrot affected and surrounding non-affected palms
in every case of disease incidence. In the third and fourth
trials,the affected tree was killed by pouring undiluted Gramax-
one in three or four holes around the trunk of the palm as soon as
the initial symptoms were noticed. The bases of surrounding trees
were drenched with Endrin as in the previous case. In all these
trials weeding was practiced at regular intervals.


 PROCEEDINGS of the CARIBBEAN FOOD CROPS SOCIETY-VOL. XX