One of the worst diseases of coconut and
is found in all coconut growing states of India. It also attacks palmyrah.
Crown damaged palms
Palms of all ages are susceptible to the disease, but it is
more frequent on young palms.
Yellowing of one or two young leaves surrounding the spindle
is the first symptom.
The heartleaf becomes yellowish-green.
Basal tissues of the leaf rot quickly and can be easily separated
from the crown.
Infection spreads to the older leaves, causing sunken leaf spots
covering the entire leaf blade.
Spot margins are irregular and water-soaked, and when the leaves
are unfolded the characteristic irregular spots are conspicuous
on the blade.
In severely affected trees the entire crown may rot and in a
few months the trees wilt.
Fungus perpetuates on the host debris,
in crevices and natural openings of the dead tissue.
With the onset of monsoon rains and favourable
temperature (18-20 °C), the fungus becomes active and infects the tender
Treated wound should be given
a protective covering till the next normal shoot emerges.
Badly affected trees which are
beyond recovery should be cut and burnt.
At initial stage of the disease when the spindle is just withering,
application of Bordeaux paste (100 g copper sulphate and 100 g quick
lime each dissolved in 500 ml of water separately and mixed together
to make one litre) on the crown after removing the infected tissue and
a thorough cleaning prevents the spread.
All the healthy palms around diseased plants should be sprayed with
one percent Bordeaux mixture or copper oxychloride
This disease is observed frequently in
every country where coconut is grown.
Since the affected part is the fruit,
its incidence causes considerable loss in yield.
There are no reported cases of the palms
being killed due to fruit-rot.
Fruit Rot affected nut
Rotting of the immature nuts is the chief symptom of the disease.
The affected nuts fall down.
Near the stalks, a discoloured area is developed, which will
appear at first water-soaked and darker green than the rest of
the surface of the nut.
Later on, the lesions turn brownish in colour and appear as
depressions due to the decay of the underlying tissues.
The pathogen appears as a whitish matty growth on the surface.
The rot extends into the husk and often even into the endosperm cavity
if the shell has not hardened.
The causal organism has been identified as Phytophthora omnivora.
The infection takes place on very tender tissues in the presence
of moisture and in humid atmosphere; the pathogen penetrates the fruit
through the mesocarp and ramifies in that region.
Consequently, decay sets in those tissues of the host leading to the
shedding of the nuts.
The pathogen is active during the rainy season and survives in the
fruit stalk during the dry weather, making itself manifest with the
onset of favourable conditions.
Fruit rot can be successfully controlled by application of a copper
fungicide, such as Bordeaux mixture, as spray or paste, on the infected
and wounded surface, preferably during the pre-monsoon and post-monsoon
To be effective, the sprayings should be given during the pre-monsoon
and post-monsoon periods.
In addition to spraying, the crowns of the palms, whether affected
or not, should be given a thorough cleaning.
The shed nuts should be collected and burnt.
Eradication of the diseased materials and their destruction on the
spot. Prophylactic spray application of the fungicide on the apparently
healthy neighbouring palms.
Regular cultural and manurial practices to maintain the palms in normal
Most prevalent in the Southern districts of Kerala.
Leaf Rot affected seedling
Symptoms on newly formed leaves
Symptoms first appear as blackening and shrivelling of the distal
ends of the leaflets in the central spindle and also in some of
the younger leaves
Blackening and Shrivelling
Later the affected portion breaks off in bits giving the infected
leaves a fan-like appearance.
Each new leaf of the diseased tree gets infected and all the
leaves of the tree show disease symptoms.
The reduction in leaf surface adversely affects the yield.
Spraying the leaves sequentially with 1% Bordeaux mixture, mancozeb
3g and Fytolan 5g/litre of water, at quarterly intervals after removing
all severely affected leaves reduces further incidences of the disease
to a considerable extent.
Stem bleeding disease was first reported from Ceylon. Later on, it
was observed in India, the Philippines, Malaya, Andamans and in Trinidad.
Ooze from cracks of coconut stem
The characteristic symptom of the disease is the exudation of
a dark reddish brown fluid from cracks in the outer tissue usually
found at the lower portion of the trunk, about 2m to 3m, from
The fluid turns black in colour as it dries up on the bark.
Large cavity in the diseased stem
The tissues beneath the bleeding patches become decayed and
The infection may occur anywhere on the trunk, but is rarely
observed on the soft portion immediately below the crown.
The symptoms exhibited by young trees are different from those
On young palms, the spread of the disease is more rapid.
Darkening of affected stem
The external patches do not indicate the extent of the internal
A general rot of the soft inner tissue takes place, leading
to the formation of a cavity in the central portion of the stem
and an accumulation of a thin yellowish fluid.
The fluid gushes out when the cavity is opened.
The decay when directed downwards to the bole, leads to the
tree becoming hollow without any external symptoms.
Spores of the fungus Thielaviopsis were observed in the liquid
which oozes out.
The same fungus was isolated from the discoloured tissue underlying
the bleeding patches.
The fungus was identified as T. ethaceticus which is identical
to Thielaviopsis paradoxa or Ceratostomella paradoxa,
the perfect stage of the fungus.
The fungus being a wound parasite, makes its entry through growth
cracks which normally occur on the coconut stem.
Different types of stem bleeding
As mentioned earlier, the bleeding observed on the coconut stem may
be due to several reasons and it might also be of different types.
Three distinct types of bleeding have been recorded in Malaya
The common type of bleeding due to the decay of the soft tissues about
five centimetres thick, in which case, the bleeding takes place from
all available cracks on the bark,
Bleeding through abandoned white-ant galleries, and
Bleeding from one single wound associated with a' New disease' recorded
The disease caused by Ganoderma lucidum is associated with
bleeding of the stem.
Bleeding patches occur at the base of the trunk all round resulting
in the slow death of the outer tissue; it extends higher up on the trunk
as the infection advances.
Occurrence of the stem bleeding due to physiological causes:
Occurring on neglected gardens following heavy manuring and subsequent
drought. In this case bleeding patches are reddish brown and circular,
extending to a diameter of about seven centimetres and commencing from
0.5 m to 1 m from the base.
The patches spread spirally about half way up the stem, and,
Bleeding due to heavy rains following drought; in this group there
are two types of bleeding
(a) in ill-drained soils following floods which does not cause much
(b) on lands with fluctuating water table; the bleeding under these
circumstances is extremely severe, the patches almost reaching the
crown and often causing the ultimate death of the palms.
The disease can be controlled to a certain extent by carrying out
the following treatments.
The infected tissues should be cut out with a chisel.
The inner affected tissues should be scooped out till no diseased
tissues remain behind and dressing the wound with tar or Bordeaux paste.
Since T. paradoxa is not considered a virulent pathogen, but
a wound parasite, palms growing under unfavourable conditions having
a large number of growth cracks are more susceptible to the disease
as the growth cracks form the foci of fungal infection.
Hence general improvement of the cultural conditions is indicated
where the disease is of common occurrence.
Ikisan - Ganoderma root rot and wilt / Baral stem rot of coconut palm
Ganoderma Root Rot And Wilt / Basal Stem Rot :
Wilt disease is common from November to June in some gardens
in South India, particularly Andhra Pradesh, Karnataka and Tamil
Weak trees are mostly affected in which the fungus infects the
roots and spreads upwards killing the entire root system.
Affected Dead tree
Ooze coming from stem tissue
Older leaves which start drooping and withering remain
suspended around the trunk for several months before they are shed.
The trees become barren due to the suppression of the
The diseased tree dies slowly and often the stem cracks,
giving out a dark brown ooze.
In advanced stages of the disease, the fungus produces
the fruiting bodies (brackets) along the sides of the basal trunk.
The diseased tree dies in about two years.
Fungus is soil-borne. Disease is more severe and spreads fast in light
soils than in black soils.
Spread is also fast during drought years.
Death of the tree is faster if there is bark eating caterpillar infestation
Difficult to control as the disease is soil-borne.
Preventive measures recommended for restricting the spread
of the disease are:
Destroying the infected palms along with the boles and roots and
preventing the spread of the fungus by digging isolation trenches about
50 cm wide 1 m deep, two to three meters away from the diseased palm
and rabbing the trenches.
Trenches dug for replanting should be filled with clay, farm yard
manure and 5 kg neem cake before planting coconut plant.
As the disease is severe in light soils, green manure crops like sunhemp
and sesbania should be grown and incorporated into the soil for moisture
retention and multiplication of antagonistic fungi.
Deep ploughing or digging which are likely to injure roots should
Circular basins of 2 m radius should be made around each tree and
irrigation given separately for each tree to restrict the spread of
the fungus from infected to healthy tree.
Apply farm yard manure (200 kg) and neem cake (5-10 kg) for each tree
during June -July months of the year.
Also apply 2 kg super phosphate and 3 kg muriate of potash per each
tree in two split doses, first in July and the second in November.
Avoid using nitrogenous and complex fertilizers.
Apply 40 litres of 1 per cent Bordeaux mixture in the basin of each
tree yearly once during August -September months.
Mix 6 ml of tridemorph in 25 ml of water and apply 3 or 4 times an
year by root feeding technique, in early stages of infection.
To control bark eating caterpillar, mix chlorpyrphos 2 ml per litre
of water and apply the bark eating caterpillar infested area with a
brush at 15 days interval.
Application of finely powdered sulphur and lime at the rate of 2 kg
each per palm to the soil around and trees is found to be beneficial.