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PLANT
PROTECTION
B.
Diseases
The
coconut palm is affected by a number of diseases,
some of which are lethal while others gradually
reduce the vigour of the palm causing severe loss
in yield. A brief account of the important coconut
diseases is given.

I.
Bud Rot
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Symptoms
-
The
earlier symptom is the yellowing of
one or two younger leaves. Black spots
appear on spindle leaves.
-
In
the later stages the spindle withers
and drops down.
-
The
tender leaf base and soft tissues of
the crown rot into a slimy mass of decayed
material emitting foul smell.
-
Ultimately
the entire crown falls down and the
palm dies.
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Control
measures
-
Remove
all affected tissue of the crown and
apply Bordeaux paste on cut end and
provide a protective covering till normal
shoot emerges (Dissolve 100 gm of copper
sulphate and 100 gm of quick lime each
in 500ml. water separately and mix to
form 1 litre of Bordeaux paste).
-
Spray
1% Bordeaux mixture on the crown of
the neighbouring palms as a prophylatic
measure.
-
Spray
with 1% Bordeaux mixture during May
and September if the disease occur frequently.
-
Cut
and burn severely affected palms which
cannot be saved.
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II.
Leaf Rot
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Symptoms
-
Blackening
and shriveling up of distal ends of
the leaflets in the central spindle
and younger leaves which later break
off in bits.
-
Gradual
weakening of the tree resulting in decline
yield.
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Control
measures
-
Improve
general condition of palms through proper
manuring and management.
-
Remove
the decayed portions of spindle leaf
and upmost two leaves only.
-
Pour
fungicide solution of Hexaconazol (Contaf
5E) - 2ml or Mancozeb (Dithane M45/Indifil
M45) - 3g in 300ml water per palm to
the base of spindle leaf.
-
Apply
20g Phorate 10G mixed with 200g fine
sand around the base of spindle leaf.
-
2-3
rounds of spraying is sufficient in
case of mild infection.
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III.
Stem Bleeding
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Symptoms
-
Exudation
of reddish brown liquid through cracks
developing on the stem.
-
Decaying
of tissues at bleeding point
-
Vigour
and yield declining.
-
Development
of big holes inside the trunk
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Control
measures
-
Chisel
affected tissue and dress the wound
with 5% Calixin (5ml in 100ml water).
Apply coal tar after 2 days. Burn off
chiselled pieces.
-
Avoid
any mechanical injury to the stem.
-
To
avoid spread of disease on to upper
portion of trunk, root feeding with
5% calixin may be adopted 3 times a
year - April-May, Spetember-October
and January-February.
-
Along
with 50kg organic manure, apply 5kg
neem cake containing the antagonistic
fungi, Trichoderma culture to the basin
during September.
-
Provide
adequate irrigation during summer and
drainage during rainy season.
-
Apply
recommended doses of organic manures
and chemical fertilizers.
-
Coconut
stem boring insects like Xyleborus,
Diocalandra should be controlled by
applying Carbaryl 50% WP on the trunk
@ 3g per litre water.
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IV.
Root (wilt) Disease
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Symptoms
-
Abnormal
bending or ribbing of the leaflets,
flaccidity of the leaves, general yellowing
followed by marginal necrosis of the
leaflets.
-
Abnormal
shedding of buttons, reduced leaves
and crown, gradual reduction in yield.
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Control
Measures
Being
a non-lethal, debilitating disease an integrated
approach is to be followed for management
of root wilt.
-
Recommended
control measures for leafrot disease
as this disease gets superimposed on
most of the root wilt affected palms.
-
Follow
integrated nutrient management
apply organic manure @ 50kg / palm /
year.
apply balanced dose of chemical fertilizers
i.e. 500g Nitrogen (1.1kg urea), 300g
Phosphorus (1.7kg Mussouriphos), 1000g
Potassium (1.7kg Muriate of potash)
in two splits - 1/3rd during April-May
and 2/3rd during September-October under
rainfed condition and in four splits
during January, April, July and October
under irrigated condition. In addition
to this 500g MgO (1kg Magnesium sulphate)
also has to be applied along with second
dose of fertilizer application.
-
Cut
and remove disease advanced, uneconomical
palms yielding less than 10 nuts per
palm per year.
-
Grow
green manure crops - cowpea, sunhemp
(Crotalaria juncea), Mimosa invisa,
Calapagonium mucanoides, Pueraria phaseoloides
etc. may be sown in coconut basins during
April-May and incorporated during September-October.
-
Irrigate
coconut palms with at least 250 litre
water in a week.
-
Adopt
suitable inter/mixed cropping in coconut
gardens.
-
Provide
adequate drainage facilities.
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VI.
Tanjavur wilt
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Symptoms
-
Decay
of finer nuts, withering, yellowing,
drooping and drying of outer whorl of
leaves and exudation of reddish brown
fluid at the base of the trunk.
Control
Measures
-
Practice
growing banana as intercrop in coconut
.
-
Root
feeding with Calixin (2ml in 100ml water)
once in 3 months.
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-
Drench
the basin with 25 litre of 0.1% Calixin.
-
Apply
neem cake containing Trichoderma @ 5kg
/palm/year.
-
Apply
recommended dose of organic manures.
-
Avoid
flood irrigation and follow drip irrigation.
-
Practice
clean cultivation and burn off diseased
plant pests.
-
Isolate
infected palms by taking trenches of
1m depth and 0.5m width around the palm
at 1.5m away from it.
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