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Horticultural crops :: Plantation ::Coconut

1. Bud Rot: Phytophthora palmivora
2. Tanjore Wilt (or) Basal stem end rot: Ganoderma lucidum (or) Anabe Roga
3. Root (wilt) Disease: unknown etiology
4. Leaf rot disease
5. Leaf blight (or) Grey Leaf Spot: Pestalosia palmivora
6. Stem bleeding disease
7. Lethal leaf blight Lasiodiplodia theobromae
8. Mahali
9. Crown chocking
10. Tatipaka Disease (Kerala wilt, Root rot, Seedling rot)

1. BUD ROT: Phytophthora palmivora
Symptoms of Damage 
Palms of all age are liable to be attacked but normally young palms are more susceptible, particularly during monsoon when the temperature is low and humidity is very high. In seedlings, the spear leaf turns pale and comes off with a gentle pull.


Description: http://agritech.tnau.ac.in/expert_system/coconut/coconut/images/diseases/butrod001.jpg

Description: http://agritech.tnau.ac.in/expert_system/coconut/coconut/images/diseases/butrod002.jpg

BUD ROT: Symptoms of Damage

  • The earlier symptom is the yellowing of one or two younger leaves. Black spots appear on spindle leaves. 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 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

Description: http://agritech.tnau.ac.in/expert_system/coconut/coconut/images/diseases/butrod003.jpg

BUD ROT: Symptoms in Adult Palm

In adult palms, the first visible symptom is the colour change of the spear, which becomes pale and breaks at the base and hangs down. The rotting slowly progresses downwards, finally affecting the meristem and killing the palms. This is accompanied by drooping of successive leaves. Even then, nuts that are retained on the palm may grow to maturity. The disease proves fatal if not checked at the early stages, before damage of the bud. 

Management

Chemical Method:

  • Remove all the affected tissue of the crown region and crown drenching with Copper oxychloride 0.25%. (Apply Bordeaux paste and protect it from rain 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 0.25% Copper oxychloride on the crown of the neighbouring palms as a prophylactic measure before the onset of monsoon. (Spray 1% Bordeaux mixture on spindle leaves and crown of disease affected as well as neighbouring palms, as a prophylactic measure.
  • The infected tissues from the crown region should be removed and dressed with Bordeaux paste or 1% Bordeaux mixture to be sprayed to reach the crown region as pre-monsoon spray (May and September).
  • Leaf axil filling with Sevidol 8G, 25 g mixed with 200g sand is recommended to red palm weevil infestation of affected palms.
  • Spray with Copper oxychloride 0.25% after the onset of Monsoon.

Note: Dwarf varieties are sensitive to copper injury. Hence Bordeaux mixture spraying should not be done. Instead place small perforated sachets containing 2-3g of Indofil M-45 in the top two or three leaf axils to control bud rot disease.

Cultural Method:

  • Provide adequate drainage in gardens.
  • Adopt proper spacing and avoid over crowding in bud rot prone gardens.

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2. TANJORE WILT / BASAL STEM END ROT; Ganoderma Wilt / ANABE ROGA
This disease first appeared in the coastal areas of Thanjavur district of TamilNadu after cyclones of 1952 and 1955 and hence the names Thanjavur wilt.  In Tamil Nadu it is prevalent in Thanjavur and Chengulpet districts. In Karnataka it is found in Maidan areas. This disease is of recent occurrence in many parts of Kerala, especially in the districts of Palakkad, Malappuram, Thrissur, Kollam, Thiruvananthapuram and Wayanad.
Causal Organism: Ganoderma lucidem and Ganoderma applanatum.

Symptoms of Damage


Description: http://agritech.tnau.ac.in/expert_system/coconut/coconut/images/diseases/tanjore_wilt001.jpg

Description: http://agritech.tnau.ac.in/expert_system/coconut/coconut/images/diseases/tanjore_wilt002.jpg

TANJORE WILT / BASAL STEM END ROT: Symptoms of damage

  • Initial symptoms of Thanjavur wilt (Ganoderma wilt) start with withering, yellowing and drooping of the outer whorl of leaves.
  • This is followed by exudation of reddish brown liquid through cracks at the base of the trunk and oozing spread upward. The tissues on the bleeding spots are soft to touch.
  • Decaying of tissues at bleeding point and rotting of the basal portion of the stem
  • The bark turns brittle and often gets peeled off in flakes, leaving open cracks and crevices. The internal tissues are discoloured and disintegrated, emitting a bad smell.
  • Bracket formation at the base of the trunk. Ganoderma appears at the base of the trunk. Ultimately the palm dies off

Management 
Cultural Method:

  • Remove and destroy all affected palms.
  • Green manure crops must be raised and ploughed in-situ at the time of flowering.

Biological Method:

  • Apply Pseudomonas fluorescens (Pf1) @ 200g/palm + Trichoderma viride @ 200g/palm/year.
  • Apply 200g Phosphobacter and 200 g Azotobactor mixed with 50kg of FYM/palm.
  • Apply FYM 50kg + neem cake 5 Kg once in 6 months along with fertilizers.

Chemical Method:

  • Isolation of trench around the tree, 4 feet away from the base of the trunk. Apply Sulphur dust inside the trench.
  • The bleeding patches in the stem may be chiseled and protected with tridemorph (5% calxin) and subsequently with hot coal tar.
  • Aureofungin-sol 2 g +1 g Copper Sulphate in 100ml water or 2 ml of Tridemorph in 100 ml water applied as root feeding. (The active absorbing root of pencil thickness must be selected and a slanting and a slanting cut is made. The solution to be taken in a polythene bag or bottle and the cut end of the root should be dipped in the solution).
  • Trunk injection / root feeding with Calixin 3 ml/tree.
  • Forty litres of 1% Bordeaux mixture should be applied as soil drench around the trunk in a radius of 1.5m.

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3. COCONUT ERIOPHYID MITE: Aceria guerreronis
Causal Organism: Phytoplasma. The disease is transmitted by lace bug Stephanitis typica and the plant hopper Proutista moesta

Symptoms of Damage

  • Seedling Stage: Flowering is delayed and also yield is considerably reduced.
  • Tapering of terminal portion of the trunk.
  • Reduction of leaf size
  • Abnormal bending or Ribbing of leaf lets termed as flaccidity.

Description: http://agritech.tnau.ac.in/expert_system/coconut/coconut/images/diseases/eriophyid_mite001.jpg

Description: http://agritech.tnau.ac.in/expert_system/coconut/coconut/images/diseases/eriophyid_mite002.jpg

Symptomps of Eriophyid Mite Damage



The characteristic symptom is the flaccidity of leaflets. This is the earliest visual symptom. In the beginning yellowing is restricted from the leaf tips to the middle of the leaves, necrosis of leaflets and deterioration and decay of root system are other salient features of the disease. The leaflets curve inwardly to produce ribbing so that the whole frond develops a cup like appearance. Abnormal shedding of buttons and immature nuts are also noticed.

Hot Spot Areas:
 Kottayam, Alapuzha, Pathanamthitta and Kollam districts of Kerala.

Coconut root (wilt) is a non-lethal debilitating disease and the affected palms survive for a long period giving a reasonably good yield. The root (wilt) affected palms are susceptible to diseases like leaf rot and pests like rhinoceros beetle and red palm weevil. So there is a chance of confusing the pests and disease symptom with the root (wilt) disease. Negligence on the management aspects aggravates the malady. Efficient management of palms suspected to be affected by coconut root (wilt) disease demands control of all pests and diseases and imparting natural resistance and health to the palms through proper manuring and agronomic practices. 

Management
 
Cultural Method:

  • 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.
  • Apply fertilizers for coconut palms in average management at the rate of 0.34 kg N, 0.17 kg P2O5 and 0.68 kg K2O / palm / year in the form of urea, rock phosphate and muriate of potash, respectively. For palms under good management, fertilizers may be given @ of 0.5 kg N, 0.32 kg P2O5 and 1.2 kg K2O / palm / year.
  • Magnesium may be supplied @ 500 g MgO per palm per year in the Onattukara region (sandy soil) and 100 g MgO in the remaining areas. The cheapest source of MgO is magnesite (MgCO3). The magnesium in magnesite is acid soluble. Hence it may be preferred in acid soils.
  • Under rainfed conditions, apply fertilizers in two splits, 1/3rd at the time of early southwest monsoon and 2/3rd before the northeast monsoon. Under irrigated conditions apply fertilizers in three equal splits (April-May, August-September and December-January).
  • Apply fertilizers in 10 cm deep circular basins at a radius of 2 m from the bole of the palm.

When the crop is grown under the bund and channel system, desilt the channel and strengthen the bunds during summer months.
Water Management (Irrigated) of Root Wilt affected Garden:



Age of Palm

Basin

Drip

Perfo/Sprinkler (HDMSCS)

1-2 years old

25-30litres once
in 2 days

10 lit per day, two emitters 50 cm from base

 -

3-4 years old

75-80 litres once
in 4 days

20lit per day, 3 emitters 75 cm from base

 -

Adult Palm

200-250 litres
once in 4 days

30-35 lit per day, 4 emitters 1 m away 
(in laterite); 6 emitters (literal sandy soil) 
Pit size for emitters – 25cm3

Irrigate to a depth of 20
mm once in 4 days

Biological Method:

    • In addition to the above, apply 50 kg cattle manure or green manure and 1 kg of lime / palm / year.
    • Growing green manure crops like sunn hemp, sesbania, cowpea and calapagonium in the coconut basin and their incorporation in situ is beneficial as the practice reduces the intensity of the root (wilt) and increases the nut yield. The ideal green manure crops for the sandy and alluvial soils are cowpea and sesbania, respectively.
    • Apply manures in 10 cm deep circular basins at a radius of 2 m from the bole of the palm.

For more details, visit - http://www.tnau.ac.in/tech/swc/eriomite.pdf
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4. LEAF ROT DISEASE
Symptoms of Damage: Leaf rot disease commonly occurs on coconut palms already affected by root wilt disease especially in 8 southern districts of Kerala, namely Thiruvananthpurma, Kollam, Alappuzha, Pathanamthitta, Kottayam, Ernakulam, Idukki and Thrissur, besides Theni – Dindigul districts (Cumbum valley) of Tamil Nadu.

The first symptom is the appearance of water-soaked brown lesions in the spear leaves of root-wilt affected palms. Gradually these spots enlarge and coalesce resulting in extensive rotting. As the leaf unfurls the rotten portions of the lamina dry and get blown off in wind, giving a 'fan' shape to the leaves. Some times, the symptom becomes very acute and the spear fails to unfurl.


Description: http://agritech.tnau.ac.in/expert_system/coconut/coconut/images/diseases/leafrot001.jpg

Description: http://agritech.tnau.ac.in/expert_system/coconut/coconut/images/diseases/leafrot002.jpg

Brown colour spots - enlarge resulting in rotting

Fan like apperance of leaves


Management
Physical Method: Remove the rotten portions from the spear and the two adjacent leaves.
Chemical Method:
Pour fungicide solution of Hexaconazol (Contaf 5E) - 2ml - 3g in 300ml water per palm to the base of spindle leaf. 2-3 rounds of spraying are sufficient in case of mild infection.
Treat the top two leaf axils with insecticide preparation. This can be prepared by mixing phorate 10 G / sevidol / carbaryl 20 g with 200 g sand or powered neem cake 250g mix with equal quantity of sand around the base of the spindle.
Spray crowns and leaves with 1% Bordeaux mixture or 0.5% copper oxychloride formulations in January, April-May and September. While spraying, care has to be taken to spray the spindle leaf. 
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5. LEAF BLIGHT OR GREY LEAF SPOT: Pestalosia palmivora
Symptoms of Damage
Minute yellow spots encircled by grayish bands appear on the surface of mature leaves of the outer whorl. 
Later they become grayish white. These spots coalesce into irregular necrotic patches. 
Complete drying and shriveling of the leaf blade are common when the infection is severe.


Description: http://agritech.tnau.ac.in/expert_system/coconut/coconut/images/diseases/leafblight001.jpg

Description: http://agritech.tnau.ac.in/expert_system/coconut/coconut/images/diseases/leafblight002.jpg

Yellow spots on leaves encircled by greyish on leaflets, later become grayish white


Management 
Physical Method: Removal of the older 2-3 disease affected leaves.
Chemical Method:Spraying the foliage with 0.25% Copper oxychloride will check the spread of the disease. Remove severely affected older leaves and burn. Spray the trees with 1% Bordeaux mixture or propiconazole 0.3%.
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6. STEM BLEEDING DISEASE: Thielaviopsis paradoxa
The progress of the disease is faster during July to November.

Symptoms of Damage

Stem Bleeding is characterized by the exudation of a dark reddish brown liquid from the longitudinal cracks in the bark and wounds on the stem trickling down for a distance of several inches to several feet.


Description: http://agritech.tnau.ac.in/expert_system/coconut/coconut/images/diseases/stembleeding.jpg

Exudation of reddish-brown liquid through cracks on a coconut trunk


The lesions spread upwards as the disease progresses. The liquid oozing out dries up and turns black. The tissues below the lesions become rotten and turn yellow first and later black.

In advanced cases, the interior of affected trunks are hollow due to decay of interior tissues. As a result of extensive damage in the stem tissue, the outer whorl of the leaves turn yellow, dry and shed prematurely. The production of bunches is affected adversely. Nut fall is also notices. The trunk gradually tapers at the apex and crown size becomes reduced in chronic cases.
Causal Organism
The fungus, Thielaviopsis paradoxa is the causal agent of the disease. The fungus was found to reproduce the symptoms on inoculation. Progress of the disease was faster during July to November. Increase in growth cracks on the trunk, severe summer followed by sudden wetting, imbalanced nutrition, excessive salinity etc. The fungus has also been found sometimes to attack leaves, petioles and nuts.

Management

Chemical Method:
Chisel out completely the affected tissues and paint the wound with tridemorph 5% or Bordeaux paste. Apply coal tar after 1-2 days on the treated portion. Burn off chiseled pieces.
To avoid spread of disease on to upper portion of trunk Root feed with tridemorph 5% (5% Calixin) 5ml in 100 ml water, thrice a year during April-May, September-October and January-February to prevent further spread of lesions.
Apply tridemorph @ 25 ml in 25 litre of water as soil drenching once in four months.
Cultural Method:
Destroy the chiseled materials by burning. Avoid any mechanical injury to trunk.
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 along with recommended fertilizer.
Apply neem cake at the rate of 5kg / palm in the basin along with other organics.
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7. LETHAL LEAF BLIGHT (LLB) Lasiodiplodia theobromae
Control Measures
Chemical Method: Spray 1.0 per cent Bordeaux mixture or 0.25 per cent Copper oxychloride or 0.2 per cent Indofil M 45 (4 times at monthly interval during February, March, April and May).


Description: http://agritech.tnau.ac.in/expert_system/coconut/coconut/images/diseases/leafblight001.jpg

Description: http://agritech.tnau.ac.in/expert_system/coconut/coconut/images/diseases/leafblight002.jpg

Yellow spots on leaves encircled by greyish on leaflets, later become grayish white

a. Preparation of 1% Bordeaux mixture 
A quantity of 400 g of copper sulphate should be dissolved in 20 litres of water and 400 g of lime in another 20 litres of water separately. The copper sulphate solution should be added to the lime solution constantly stirring the mixture. Earthen or wooden vessels alone should be used and metallic containers should not be used. To find out whether the mixture is in correct proportion, a polished knife should be dipped in the mixture for one minute and taken out. If there is reddish brown deposit of copper, additional quantity of lime should be added till there is no deposit in the knife.

b. Preparation of Bordeaux paste

Take 200 g of Copper sulphate and dissolve it in one litre of water and 200 g of lime in one litre of water separately. Both are mixed simultaneously in a third vessel and the resultant mixture can be used as a paste.
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8. MAHALI OR FRUIT ROT AND NUT FALL
Causal Organism
Fungus: Phytopthora palmivora. The pathogen is more active during the rainy season when the atmospheric conditions are favourable for its growth

Symptoms of Damage

Shedding of female flowers and immature nuts are the common symptoms 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.

Control Measures

Chemical Method: Spray 1% Bordeaux mixture or copper oxychloride preparation (0.5%) on the crown of palms, once before the monsoon and once or twice later on at intervals of 40 days. 
In dwarf palms, apply Dithane M-45 in place of Bordeaux mixture. Source: KAU)
Physical Method: Remove and destroy fallen nuts.
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9. CROWN CHOCKING
Crown choking disorder is commonly observed in Assam and West Bengal.

Symptoms of Damage

Characterized by emergence of shorter leaves with fascinated and crinkled leaves.
The leaflets show severe tip necrosis and fail to unfurl. In many cases, it gives a choked appearance to the frond.
Ultimately the affected palm dies.
Control measures
Application of 50 g Borax at half-yearly intervals (Feb-Mar and Sept-Oct) along with recommended fertilizer in the basins will control the disease when it is in the early stage. In root wilt affected areas a dosage of 200gm - 300gm per palm per year is recommended.
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10. TATIPAKA DISEASE
First appeared in Tatipaka village of East Godavari district of Andhra Pradesh, following a cyclone in 1949. This is endemic to East and West Godavari, Srikakulam, Nellore, Krishna and Guntur districts. Palms in the age group of 25 to 60 years are more susceptible.
Symptoms of Damage
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 producing progressively shorter leaves.
The stem begins to taper. The leaves give a fascinated appearance due to improper unfolding of leaflets. The affected tree produces smaller bunches with atrophied barren nuts.
The causal agent is suspected to be Phytoplasm. 

Management
The spread disease can by arrested by systematic surveillance and rouging of diseased palms.



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