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Bud Rot > Bacterial Leaf Blight > Fruit Rot > Leaf Blight > Leaf Rot > Little Leaf > Mahali > Stem Bleeding > Tatipaka Disease > Ganoderma Root Rot >


Ikisan - Coconut Bud rot

Bud Rot :

Phytophthora palmivora

  • One of the worst diseases of coconut and is found in all coconut growing states of India. It also attacks palmyrah.

Symptoms

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.

Etiology

  • 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 host tissue.

Control

Budrot treatment

  • 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 (3 g/l).

 
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Ikisan - Baterial Leaf Blight of Coconut

Bacterial Leaf Blight

  • Bacterial leaf blight is a serious disease of coconuts during wet seasons.

Symptoms

Leaf blight affected leaf

  • The drying up of the leaves from the tip downwards, the progress of infection being from the older leaves to the younger.
  • The worst affected palms present the appearance of severe drought-affected trees.
  • The infected leaflets may appear either at the base of the petiole or along the whole length of the rachis.
  • Diseased as well as healthy leaflets in many instances appear intermingled on the rachis.
  • Dark coloured lesions are found on the back of the midribs of the affected leaflets.
  • They appear yellowish in colour, turning in course of time to a lighter green water-soaked zone, which, while fresh, is quite transparent when held up against light.
  • On examination, almost transparent whitish bacteria are seen lining the edge.
  • In the most advanced stages, the diseased areas become mottled in appearance and gradually become more pitted and stand out prominently, especially near the edges of the diseased zone.
  • Often confusion arises between the bacterial blight and leaf spot (blight caused by Pestalotia palmarum).
  • However, the lesions caused by P. palmarum are smaller and are more or less with a regular margin.
  • The dark pustules of Pestalotia infection are absent in the bacterial disease.

Control

  • Adopt the method of 'cutting and burning' the affected materials is considered to be effective.

 
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Ikisan - Fruit Rot of Coconut

Fruit Rot:

Phytophthora omnivora

  • 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.

Symptoms

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.

Etiology

  • 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.

Control

  • 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 periods.
  • 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 vigour.

 
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Ikisan - Leaf Blight or grey leaf spot of Coconut

Leaf Blight /Grey Leaf Spot :

Pestalotiopsis palmarum

  • Leaf blight is common in most of the coconut growing states, particularly severe in Kerala.

Symptoms

  • Disease symptoms develop in the mature leaves of the outer whorl.
  • They appear at first as minute yellow spots encircled by a greyish band on the leaflets.
  • It is characterized by the formation of greyish-white spots surrounded by a brown band.

Leaf blight affected leaves

  • These spots coalesce into irregular necrotic patches. Gradually, the centre turns greyish white and the brown band darken.
  • Complete drying and shrivelling of the leaf blade are common when the infection is severe.

Control

  • Removal of the older affected leaves and spraying the foliage with 1 per cent Bordeaux mixture will check the spread of the disease.
  • Improving drainage conditions, application of potassic fertilisers.

 
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Ikisan - Leaf Rot of Coconut

Leaf Rot :

Bipolaris halodes

  • Most prevalent in the Southern districts of Kerala.

Symptoms

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
of leaflets

  • 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.

Control

  • 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.

 
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Ikisan - Little Leaf or Point Disease of Coconut

Little Leaf Or Pencil Point Disease

  • This disease is manifested by palms growing under unsuitable environment or is usually a symptom of ageing.
  • The characteristic symptom of the disease is the steady dwindling of the girth at the top of the trunk that gradually tapers to a pencil point.
  • The crown at the same time gets reduced both in number and size of the leaves.
  • The axillary inflorescence do not develop properly in advanced cases.
  • When this condition is reached, it is not possible to restore the palm to normal condition by cultural or manurial treatments.
  • In the early stages of the disease, proper attention should be paid to plantation management, especially in rectifying deficiency of plant nutrients.

 
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Ikisan - Mahali or Fruit Rot and Nutfall of Coconut

Mahali Or Fruit-Rot And Nut-Fall

: Phytophthora palmivora

  • This is caused by the fungus Phytophthora palmivora.

Symptoms

  • Dropping of the buttons, before and after fertilisation and of young and nearly mature nuts in large numbers is the chief symptom of the disease.
  • Near the fruit 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.
  • In course of time, these lesions turn brownish and appear as depressions due to the decay of the underlying tissues. The fungus appears as a whitish matty growth on the surface.
  • The rot extends into the husk and often into the kernel cavity especially when the shell has not hardened. At times the axis of the inflorescence gets affected.
  • The disease is usually prevalent in coconut palms growing in association with areca palm.
  • It is usually virulent after the rains of the S.W monsoon when the atmospheric humidity is high.

Control

  • Fruit rot can be successfully controlled by spraying the bunches with 1% Bordeaux mixture to be effective, the treatment 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 also be collected then and there and burnt.

 
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Ikisan - Stem Bleeding in Coconut

Stem Bleeding

Occurrence

  • Stem bleeding disease was first reported from Ceylon. Later on, it was observed in India, the Philippines, Malaya, Andamans and in Trinidad.

Symptoms

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 ground.
  • 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 yellowish.
  • 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 described above.
  • 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 decay.
  • 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.

Etiology

  • 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 in Malaya.
  • 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 damage; and
    (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.

Control

  • 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.

 
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Ikisan - Tatipaka disease of Coconut

Tatipaka Disease:

Phytoplasma

Occurrence

  • Disease first observed in Tatipaka village of East Godavari district in Andhra Pradesh, and hence the name.

Symptoms

Tappering of stem

  • Plants between 25-60 years age are most susceptible.
  • Development of an abnormally large crown with dark green inner leaves and higher yield is the precursor of disease incidence.
  • Subsequently the crown becomes smaller in size and stem begins to taper.

Improper unfolding of leaflets

  • The leaves give a fascinated appearance due to improper unfolding of leaflets.
  • Leaves bend in the middle abnormally. Yellow spots appear on the leaves.
  • Leaf number is reduced.
  • The affected tree produces smaller bunches with atrophied barren nuts.

Control

  • Remove and destroy affected trees.
  • Avoid using nuts from infected tree for nursery and raise seedlings only in disease free gardens.
  • Avoid transport of seedlings from infected areas.

 
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Ikisan - Ganoderma root rot and wilt / Baral stem rot of coconut palm

Ganoderma Root Rot And Wilt / Basal Stem Rot :

Ganoderma applanatum

Bracket of Ganoderma

  • Wilt disease is common from November to June in some gardens in South India, particularly Andhra Pradesh, Karnataka and Tamil Nadu.
  • Weak trees are mostly affected in which the fungus infects the roots and spreads upwards killing the entire root system.

Symptoms


Ganoderma
Affected Tree

 

Ganoderma 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 inflorescence.
  • 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.

Etiology

  • 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 also.

Control

  • 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 be avoided.
  • 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.

 
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