Control of Pests and Diseases

Control of Pests and Diseases

6.1 Pests

I. Insects
II. Mammals
III. Minor Insects



It damages the husk of the coconut plant initially and the base subsequently. When the nut is examined the damage to the husk will be visible. Withering of the shoot also could be seen. When the withered shoot is pulled by hand it will easily come out.


If the damage by termites is minimum it has to be removed and for chemical treatment 1-2 mls of “Itdakloprid 20% “ dissolved in 1L of water and the plant should be submerged for about 3 minutes.


This attacks plants up to 5 years of age. The insect lives in the unopened long leaves. Long lines and spots will get visible and become brown coloured and dried up later.


Chemical treatment is injecting in to the shoot Carbosalfan 3ml diluted in I L of water .

3.Black beetles

Here the shoot shall get seriously damaged resulting in withering of the growth and delay in flowering. The area of the shoot shall get damaged and if the small plants get attacked the shoots shall get withered away or become crooked.


It is important to maintain cleanliness of the land. Beatles lay eggs on organic matters, hence coconut trunks, cow dung, rubbish heaps must be removed.

Keeping two camphor balls on fronds closer to the shoot and applying burnt engine oil on the fronds surrounding the shoot. Placing of peramone traps purchased through the Coconut Development Officer of the area.

4.Red beetles

This is the death knell of the coconut plantations and coconut trees of 3 to 10 years of age get affected. The eggs are laid in the cracks of the trunk, soft roots, damages etc. Worm gets out of the egg gets in to the trunk and attacks the internal tissues resulting fall of the tree either at the shoot or at the base.

* Holes in the tree
* Visibility of essence near holes
* Fronds becoming pale yellow
* Withering of the shoot
* Hearing of sounds when ear is placed on to the trunk


One of the following methods can be used for Control

* To check carefully the trees available, between 3 to 10 years of age
* To cover big holes using cement
* When branches are cut off to leave about three feet and applying burnt engine liquid tar oil
* To close the holes at the bottom of tree with soil.
* Removing damaged trees, cutting to small pieces and burning down.

Recommended chemicals

I. Monocrotopose

40 ml injected to the matured tree trunk by using an auger

II. Penthoyite 500 EC

Divide in to 3 equal portions 40ml. Drill three holes of equal height 6” above the damaged area and applying the portions.

III. Vertaco

Dissolving 40g in 250ml of water and injecting through two holes made 1-2 feet of height. For each hole 30ml has to be injected. Syringes must be used and after 3 days holes must be covered using cement.

Additionally through the Coconut Development officer of the Area, advice on Red Beatles peramone traps and instructions and using in the field.

5. Mita

This has become a major crisis to the coconut plantations in the island. Small tender coconut get damaged through this. Mita live about three months feeding on the soft cells of the small tender coconuts.

When observed a yellow coloured triangular spot appears and it grows gradually and become brown coloured, resulting in:

* Falling of nuts
* Smaller nuts


* Using Sulphur- Palm oil mixture Sulphur and (add the method of making the mixture)- How to make the mixture: to 800 ml of water add and mix soap powder 12 gms and sulphur 5 gms well and add palm oil 200 ml)
* Using natural enemies of pests


When considering the coconut plantations, this damage too is substantial. The damage is more during the plant stage and when bearing nuts.

* Wild boar
* Wild rat
* Porcupine
* Ape
* Monkey
* Elephants
* Giant Squirrels


* Surrounding plants with barrels
* Fixing poles and tie those with plastic sheets
* Using tyres filled with soil
* Planting glydisira
* Using fire crackers

Minor Insects

1.Yellow spotted locust – Aularchesmiliarris


The first record that the yellow-spotted locust damages the vegetation was in 1947. This pest had been seen in many parts of the Island and records indicate its population had heavily increased in many instances. Female pupa makes a hole in the soil and lays eggs about 3-4 inches below the ground in cluster form. Each cluster may carry 15-60 eggs. It creates a cover with phlegm to protect the eggs.Laying of eggs take place mostly in October and November it selects areas well covered under large trees. The insects coming out of the eggs are brown in colour. Within 1-2 days those will become black in colour and yellow coloured lines could be seen along the bodies. There will be 6 stages of larvae of the yellow spotted locusts and it will take 5-6 months to complete the larva stage. This pest lives in groups and each group will have 3000-4000 or more. The locust is about 1 ½ inches in length and a grown locust will be about 5 c.m. (2 inches). Itshead and antennas are black in colour.

Damage and how to recognize

It eats the leaves of the coconut trees.


⦿ A collective effort is needed to control the yellow spotted locusts and should be vigilant for its arrival. During the months of October and November those will arrive under the shade of large trees and it is possible to collect them with hands and destroy. At this stage the pupas are not active and those could be collected with hands.

⦿ Through identifying the doubtful areas where the pupas have laid eggs and turning the soil and exposing the clusters of eggs to sunshine and allowing the birds (especially mynahs), ants to eat in order to destroy.

⦿ Making a mixture with 2 liters of water, 10 m.l. of kerosene and 10g of soap in a bucket and collecting the pupas in to the bucket. As the pupas are dormant in the morning due to low temperature collecting those has to be done in the morning hours.

⦿ When the damages are acute spray carbosulfan 3m.l. mixed with 1 liter of water.

2. Coconut scale


Coconut scale is a species that destroys coconut leaves in all areas where coconuts are planted in Sri Lanka. Since dry season is conducive for their growth, during long droughts these pests could be seen often. Their population will decrease during rainy season.These pests sucking the juices under the coconut leaves could be seen by using a magnifying glass. Center of these pests is yellow in colour and surrounded by a transparent cover similar to a fried egg (bulls eye).

Damage and how to recognize

Affected coconut trees could be easily identified by the small yellow coloured spots on the coconut leaves. When examine under the leaves these pests could be detected. Those are yellowish-white in colour. When the affected areas of the leaf scratched with a finger nail there will be a wetness with moisture if the live pests are available, if the pests are dead there will be a dried powdery feeling to the touch and scales will get gathered around the end of the finger nail.When the pest population is heavy the whole coconut branch will become yellow in colour and get dried up. At this stage it can damage the flowers and small very tender fruits. When the plants get damaged the growth will be affected.


⦿ Agronomical methods – If the damage is seen only on a few fronds those could be cut off and burnt. If the damage is detected on the small plants those leaves could be cut off or crushed by hand.

⦿ Bio control methods – Lady bird insects are natural predators capable of controlling these pests. There are two varieties – one is known as “Chilocorus nigritus” – a round shaped insect of a size of a pepper seed and the other is “Pallas sirumpilinus” and it is slightly smaller than the previous one. Its worms are white in colour and a spreading similar to the shape of fingers on its body. Both these varieties are greedy eaters and could successfully control the damage by coconut scales

⦿ Chemical methods- These methods should be considered only if the bio controlling methods had not been successful in controlling the pests. Advice of the coconut development officer of the area has to be obtained. A mixture 20-40 ml of dimetholate 40% and hoklopairofos 40% mixed with 10 liters of water has to be sprayed on the plants using a knapsack sprayer. For grown up trees 8 m.l. of mokrotopos 60% can be injected in to the trunk.

3. Nettle caterpillar


This caterpillar is known as a pest that damages severely the coconut leaves in the coconut plantations in the dry zone which had not come to much attention. This pest damages the growth in all stages from nursery to the grown trees. At the grown stage the pest is a moth and both sides of its head is light green and wings are light brown in colour.

Damage and how to recognize

Dark brown patches could be seen underneath the coconut leaves. When the caterpillars gradually grow they destroy all the leaves leaving only the ekles. As they like the well matured leaves there is a tendency to gradually damage from the lower branches to upper branches.


⦿ If the damage is for 50 or less trees the lower branches could be cut off using a picker and burnt down.

⦿ The parasite “Apantalis Parase” is used as a natural predator. Its behavior depends on the weather patterns. Instructions must be obtained from the Coconut Development officer.

⦿ Only when the effectiveness of the parasite is not satisfactory, it is recommended to use pesticides. 8 m.l. of monocrotopos 60% to be injected in to the trunks.

4. Eliminus Hypermestra


This caterpillar damages the plants in the nursery and the coconut plants.

Damage and how to recognize

⦿ Small leaves are eaten as cut by a small pair of scissors.


⦿ Destroying the caterpillars after collecting by hands. Spraying mixture of carbosulfan 3 m.l. in 1 litre of water

6.2. Diseases

i. Oozing out sap from the bark
ii. Rotting and Withering of leaves
iii. Rotting the shoot

1. Oozing out sap from the bark


Oozing juices out of the coconut trees is a common occurrence. However if the tree is infected with fungus “Cerosistas Paradoxa” treatment must be done to control the disease.

Damage and how to recognize

⦿ The main symptom is oozing out red-brownish sap out of the length-wise cracks on the bark. The oozing out spaces will gradually become brownish and finally turned in to a colour of blackish

⦿ Tissues under the bark where the sap is oozing out will turn yellowish and later will become brownish and get rotten away. Finally the whole area will get decayed leaving out only the fibre. Places where the sap oozes out will gather together and form large oozing out areas. After some time oozing will stop and the sap will get thickened and become like a gum.

⦿ This could be seen in the trees infected with the “Ganodarma” fungus. It is very seldom such infected trees available in Sri Lanka and the special feature is forming mushrooms on the trunk closer to the ground level.

⦿ Due to burning of fire; lightning; red beetle damages; excessive usage of chemical fertilizer; floods and frequent changes of water levels the oozing out of sap could take place. It is easier to identify the trees affected by burning fire and lightning.


⦿ Sick yellowish parts of the bark should be cut and removed by a sharp knife, a chisel or a hand adze. Till the healthy light red coloured tissue appears, sickly tissues must be removed. The parts removed must be burn down. “Bordeaux mixtures” or a fungus remover containing copper must be applied on the scratched out parts (wounds). If a fungus remover with copper is used the quantity
has to be according to the instructions given in the label. After leaving for a few days to get dried up, Bordeaux mixture must be re applied.

⦿ After about 10 days, if the malady has not spread to other parts or the oozing is not visible, liquid tar to be applied on the scratches (wounds). If it is difficult for cultivators to make the Bordeaux mixture, after cleaning off the oozing out sections liquid tar could be applied.

2. Rotting and Withering of leaves


Disease known as Weligama withering and rotting of leaves was found in 2000 in the Southern Province.Now it has spread over entire Matara district and in several divisional secretariats in Galle and Hambanthota districts.This disease was reckoned as an incurable pathogenic to “ficoplasma”. Through the gazette notification 1542/7 of March 24 2008 issued under the No. 35 of 1999 Act of Protection of Trees, it has been published this malady as a pandemic. In order to control the spread a buffer zone as an area without the disease.

Damage and how to recognize

⦿ Forming of brown patches due to getting wet with water on the young fronds

⦿ Leaves getting attached to the shoot

⦿ Branches getting rotten and becoming blackish and looking as “fishing rods”

⦿ Leaves not rotted being in green colour but the ends getting blackish and shrinking

⦿ Uppermost part of three getting shrunk

⦿ The trunk getting thinner

Are the main symptoms of this diseas.

⦿ Leaves getting flat and bent like ribs

⦿ Yellowing of the lower branches

⦿ Occasionally yellowing the middle branches

⦿ Getting the edges of the leaves got yellow coloured Dried up

Are the symptoms of the disease of Weligama withering of leaves.


⦿ Tebukonosol – polikar / orayis and hexakonasol – shakthi/ kantap are the recommended fungus removers. Polikar / orayis 10 ml should be mixed with 1 litre of water. Shakthi / kantap 10 ml should be mixed with 1 litre of water. When fungus removing mixtures are made plastic utensils must be used. Must cut off the parts of the tender coconut frond after climbing to the uppermost part of the tree. 3-4 branches closer to the shoot and the leaves got rotten must be cut off. About 1 litre of the fungus remover must be poured in to the shoot. The cut and removed parts along with the rotten ones should be burnt down. Later on when the fungus remover is used it is not necessary to remove the rotten parts. But the new shoot must be widened and fungus remover must be poured in to get the shoot properly wet. This has to be continued for 3-4 months except during rainy season. It is important to have a proper knowledge in using fungus removers.

3. Rotting the shoot


This is due to fungus called “phytophthora palmivora”.

Damage and how to recognize

⦿ This disease is most prevalent among the trees less than 45 years of age. The initial symptom is the fading of colour of the tender frond and getting withered. After that it will become brownish and dried up.

⦿ The infected branch easily comes out when pulled. There will be an acute odour.

⦿ The healthy branches closer to the tender branch, though green in colour, will get dried up one by one. Finally the shoot and dried up branches will wither away and fall down.


When the disease is identified in the first instance it could be controlled by recommended treatment.

⦿ The infected shoot has to be cut off and fungus remover with copper 1% or a fungus remover containing metalaxical 4g s mixed with 1 litre of water should be used to wash well the shoot twice a week.

⦿ To save the surrounding trees dithiocarbamate 6g s or metalaxical 4g s dissolved in 1 litre of water and with the mixture wash the shoots well once in three weeks during rainy season

⦿ Furthermore, through managing properly the nutrition’s the strength of the trees could be maintained. For this purpose it is important to use a balanced fertilizer mixture.

N:B: It is not possible to save the trees acutely affected by the disease. It is very important to burn down such trees. Through this step getting healthy trees infected as well as increasing the germs in the affected trees could be controlled.