Cocoa disease Phytophthora, Pantorhytes weevil

School Science Lessons
(CocoaProj2)
2024-08-28

Cocoa Project 2.
Contents
23.0 Pests and diseases
Pesticides, Preface

23.0 Pests and diseases of cocoa
Main pests and diseases, in order of world severity
1. 23.2.1 Black pod, Phytophthora pod rot, Coconut budrot, Phytophthora palmivora, Americas, Asia, Caribbean, West Africa.
2. 23.2.2 Witches' broom disease of cacao, Moniliophthora perniciosa, Caribbean, South America, West Africa
3. 23.2.3 Frosty pod rot, Moniliophthora roreri, South America, West Africa
4. 23.2.4 Mirids, Cocoa capsids, (Distantiella theobroma), Ethiopia, West Africa
5. 23.2.5 Cocoa swollen shoot virus disease, (CSSVD), West Africa.
6. 23.2.6 Cocoa pod borer, Conopomorpha cramerella, Pacific Islands, South Asia, Southeast Asia
7. 23.2.7 Vascular streak dieback, (VSD), Oncobasidium theobromae, Papua New Guinea, Southeast Asia, West Africa
Other pests and diseases
23.2.8 Brown root rot, brown tea root disease, Phellinus noxius, Asia, Australia, Caribbean, South America, West Africa
23.2.16 Cacao webworm, Pansepta teleturga, Papua New Guinea
23.2.9 Ceratocystis wilt of cacao, Ceratocystis cacaofunesta, Central and South America
Cocoa sunscald & cherelle wilt, natural physiological process, not a disease
23.2.10 Cocoa weevil borer, Pantorhytes biplagiatus, Papua New Guinea, Solomon Islands
23.2.11 Coconut bug, Amblypelta cocophaga Fiji, Papua New Guinea, Solomon Islands
23.2.12 Coconut termite, Neotermes rainbowi, Papua New Guinea
23.2.13 Giant African snail, Achatina fulica, Solomon Islands
23.2.14 Thread blight diseases (Marasmius spp.) Asia, Pacific Islands, South America, West Africa
23.2.23 Cocoa mealybug
23.2.15 Longicorn stem borers, Glenea lefebueri, Papua New Guinea
23.2.17 Pink disease, Erythricium salmonicolor, Pacific Islands
23.2.18 Rodents, rats
23.2.19 Swarming leaf beetles, Rhyparida spp., Papua New Guinea
23.2.20 Thread blight, Corticium incisum
23.2.21 Weeds, Mistletoe
23.2.24 Broad mite (Polyphagotarsonemus latus)
23.2.25 Grey weevils, (Hypotactus ruralis)
23.2.26 Cocoa root chafer (Dermolepida spp.)
23.2.27 Leaf-eating caterpillars and psyllids, Papua New Guinea

23.2.1 Black pod disease, Phytophthora palmivora
See diagram 55.2.1: Black pod disease 1
See diagram 55.2.6: Black pod disease 2
Black pod, Phytophthora pod rot (PPR), Coconut budrot, "phytophthora", (Phylum Oomycota, Family Peronosporaceae), is a major invasive disease of cocoa in regions of high rainfall and high humidity, caused by Phytophthora palmivora in South America, and Phytophthora megakarya, in West Africa.
It infects cocoa pods, flower cushions, young shoots, stems and roots, mainly during the rainy season.
Phytophthora species are water moulds, (oomycetes), not fungi, but can be controlled by fungicides.
Phytophthora seedling blight In the plant nursery a seedling blight may cause death of soft young leaves, beginning at the tip, then forming a V-shaped patch of dead tissue.
The symptoms of the disease are that brown circular patches appear on the pod, usually down near the tip first.
The brown patches gradually spread upwards, become black, and after about 10 days, the whole pod has a blackish appearance and the beans inside it are rotten.
The brown patches may have a characteristic fishy smell.
The body of the fungus is like fine white threads of cotton.
It makes spores that get into drops of rainwater on the outside of the pod.
Infection of the young leaves start at the leaf tip and follow the veins, turning the leaf brown.
Infection of trunk and branches causes red cankers when the Phytophthora grows into the tree.
Infection can be spread by flying beetles, Oecophylla smaragdina, rainbow ants Iridomyrmex cordatus, rats and the shade tree.
Control methods:
* Frequent inspection, every two days.
* Frequent harvesting, pick the ripe pods regularly, every one or two weeks.
* Count and record the number of infected pods removed during the weekly removal of infected pods, carry them away from the cocoa plot and burn them.
* Do not touch healthy pods after touching diseased pods or you may spread the spores that cause the disease.
* Do not open ripe pods near the cocoa trees, because the disease may grow on the old pods left lying nearby.
* Cut down trees to increase the flow of air through the cocoa trees and so make the air drier and not a good place for the fungus spores to grow.
* Protect apparently healthy pods with regular spraying of copper-based fungicides and the systematic fungicide Metaxyl, (C15H21NO4), Ridomil, if recommended.
1. A spray mixture used if more than one third of the pods get black pod disease.
Add half a kilo of bluestone (copper sulfate soluble), CuSO4.5H2O, to four litres of water and stir until it is dissolved.
In a separate bucket put half a kilo of hydrated lime (slaked lime, calcium hydroxide, Ca(OH)2), into four litres of water and stir until it is dissolved.
Pour both solutions into a 20 litre container, then stir this mixture well.
Spray the mixture at flowering, when the young pods set and when the pods are mature.
Spray this mixture on the leaves, above the pods and on the trunk until the spray is dripping off the pods.
Use this spray on the same day as it is mixed.
2. Spray metalaxyl 0.5% WP (Ridomil Plus 72 or Laxyl Copper, 5 g per litre water).
3. A trunk injection with potassium phosphonate, (KH₂PO₃. K₂HPO₃) may significantly reduced Phytophthora pod rot and increase pod yield.
Use of potassium phosphonate or phosphorous acid, (H3PO3), does not contaminate the environment.
The disease may be spread by ants, beetles, pod-borers Characoma stictigrapta, and infected pods and pod husks.
Avoid this disease by planting recommended hybrid varieties known to show resistance to this disease.

23.2.2 Witches' broom disease of cacao, Moniliophthora perniciosa
See diagram 55.25: Witches' broom infection.
The fungus Moniliophthora perniciosa (Crinipellis perniciosa), (Division Basidiomycota, Family Marasmiaceae), causes Witches' broom disease, attacking species of Theobroma and Herrania.
It has caused devastation for 20 years to major cacao-farming regions in South and Central America.
It can disrupt hormonal balance, provoking hypertrophy and hyperplasia followed by tissue necrosis.
The intercellular mycelium is typically swollen and convoluted.
The life cycle, including mode of reproduction, has yet to be understood.
Initial infection by Moniliophthora perniciosa basidiospores occurs in growing cacao meristems, causing a disorganized proliferation of new broom-like shoots in the host called "Witches ' brooms".
The live green "brooms" eventually die giving the characteristic dry Witches ’ broom attached to the tree.
Potential crops are lost when clusters of flowers produced on "cushions" on the main trunk and older branches are infected, producing seedless strawberry-shaped or carrot-shaped fruits.
Also, Moniliophthora perniciosa attacks cacao pods in the early stages of development, penetrating the husk and destroying the seeds.
In the wet season, the fungi in the dead brooms multiply, spores are released at night and are spread by air currents or by water, to infect young cocoa plants.
"Fan Brooms" form on fan branches either at the tip of a shoot or on side shoots.
"Grown through brooms" grow away from the original infection.
"Star blooms" are large flowers on flower cushions, which do not produce pods.
Infected pods are distorted and may have brown blotches surrounded by yellow zones.
Control methods:
The best control is to remove and burn all diseased brooms, pods and flower cushions at the end of the dry season by making cuts into the tree.
Plant selected hybrids
Green-fruited Forastero has been crossed with Trinitario types to produce hybrid cocoa seedlings, which are more disease resistant types, (especially Witches’ Broom).
Prune trees of excessive vegetation.
Spray pods with a copper-based fungicide.

23.2.3 Frosty pod rot, Moniliophthora roreri
See diagram 55.27: Pod infected by Frosty pod rot.
Frosty pod rot, Moniliophthora roreri, (Division Basidiomycota, Family Marasmiaceae), is an invasive disease in South America, has a limited geographic range, but unlimited potential of damage, a fungal pathogen), that invades only actively growing pods of cacao, Theobroma cacao, and related species.
Frosty pod rot damages pods and the commercially important seeds that some of these species produce.
Moniliophthora roreri is found in 11 countries in tropical America.
Frosty pod rot is more destructive than black pod (Phytophthora spp.), and more dangerous and difficult to control than Witches' broom, caused by Moniliophthora perniciosa.
During heavy rainfall, a thick layer of white, "frosty", mycelium develops on the surface of the pods, containing billions of dry powdery spores that can easily be disseminated by wind, water, insects or humans.
Control methods:
The best control is to remove infected pods, but do not infect other clean pods in the process.
Use recommended fungicides and resistant cultivars.

23.2.4 Cocoa capsids, Mirids, (Order Hemiptera, Family Miridae)
See diagram 55.1.1: Cocoa capsids.
See diagram 55.28: Distantiella adult.
The cocoa capsids, mirids, mirid bugs: Distantiella theobroma and Sahlbergella singularis are important pests of cocoa in West Africa where cocoa is grown without shade or where there are breaks in the cacao canopy.
Severe damage by mirids causes some cocoa trees to lose the crown completely, leaving pole-like trunks bearing many lateral chupons.
Damage is made worse by invasion of the fungus Calonectria rigidiuscula.
See diagram 55.20: Helopeltis theivora.
Helopeltis theivora, (Tea mosquito bug), occurs on cocoa and tea in Indonesia, Malaysia, Papua New Guinea, West Africa.
Pseudodoniella species, occurs on cocoa and fig in Papua New Guinea, and have a distinct hump on the back.
1. Cocoa capsids, (cocoa mirids), are sucking insects that feed mainly on the husk of cocoa pods and young shoots of chupons and fans.
Their piercing mouth parts suck up sap and inject their saliva, causing abnormal shape, dark markings called lesions on pods, shoots, petioles, leaf midrib.
The black angular spots on the leaf surface and small black, blister-like spots on the pod surfaces are caused by their toxic saliva.
Feeding on shoots causes death of terminal branches and leaves, causing dieback.
Secondary damage of canker and dieback occurs when the lesions are invaded by parasitic fungi, e.g. Calonectria and Fusarium species.
In very serious infection, the entire tree looks stunted or burnt and crop losses of more than 30% of production.
Cocoa Capsids may cause heavy losses of pods at all stages of development, especially during wet periods.
2. Capsids may occur at a break in the cocoa shade canopy, followed by growth of vegetative chupons.
Feeding on fan branches results in damage to the tree canopy that causes more damage to exposed cocoa in the dry season, called "capsid blast".
3. The female adults lay eggs in the outer layer of pods and beneath the bark of young shoots, chupons, then five nymph stages, incubation period of 2-17 days.
The adults are about 5.5 cm long and the nymphs, are smaller and have no wings.
4. Alternative hosts, include silk cotton trees, Bombax ceiba, Cola species and Leucaena leucophylla, formerly used as a shade tree.
5. Control methods:
Apart from ants, mirids appear to have few natural enemies except possibly some pathogenic fungi.
Check the cocoa trees for mirid damage on a regular basis.
Control mirids by regular weeding, 60-70% shading for young cocoa and 40-50% shading for adult cocoa, cut chupons at tree base, and no severe pruning.
For control by ants, little fire ant, Wasmannia auropunctata, black ant, Dolichoderus thoracicus, See 9.34.2 yellow crazy ant, Anoplolepsis longipes, have been used.
6. It was said that if more than 10 live adults occur on 100 trees, then chemical control measures are needed.
Previously, mirids were controlled with an insecticide, e.g. "Gammalin 20", Lindane, (BHC), followed by a second spray time to kill the bugs from eggs that were not killed by the first spraying.
However, adverse side effects of persistent chemicals, including destruction of non-target beneficial insects, e.g. midges, and long lasting residual effects on the environment, make using Lindane as undesirable and banned by international treaties.
Insecticides
The following insecticides may be used on mature cocoa, if approved by the local agriculture extension officer.
| synthetic organic thiophosphate, chlorpyrifos, (C9H11Cl3NO3PS), granules, (Chlorpyrephos, Dursban, Lorsban).
| synthetic carbamate, propoxur, 2-Isopropoxyphenyl methylcarbamate, (C11H15NO3), (Apocarb).
| synthetic organothiophosphate, phosphoramide, acephate, (C4H10NO3PS), (Orthene, Acetamidophos, Ortran).
| synthetic neonicotinoid, imidacloprid, (C9H10ClN5O2), (Premise 75, Confidor, Provado).
| synthetic pyrethroid ester, Bifenthrin, (C23H22ClF3O2), (Capture).
| synthetic pyrethroid cyclopropanecarboxylate ester, lambda-Cyhalothrin, (C23H19ClF3NO3), (Karate).
| synthetic pyrethroid ester, cyclopropanecarboxylate ester, delta-methrin, (C22H19Br2NO3), (Decis).
| synthetic pyrethroid ester, carboxylic ester, cypermethrin, (C22H19Cl2NO3), (Cymbush, Ripcord).
See Preface, Pesticides can be replaced by using local resistant varieties or resistant varieties or mixed hybrids from government authorised seed gardens.

23.2.5 Cocoa swollen shoot virus disease, (CSSVD).
See diagram 55.29: Pods infected by CSSVD.
Cocoa swollen shoot virus disease, (CSSVD), caused by Cacao swollen shoot virus, (CSSV), (Family Caulimoviridae, Genus Badnavirus), is transmitted by mealybugs and is a serious constraint to cocoa production in West Africa.
The symptoms, which may be difficult to identify, are leaf discoloration, swollen stems and roots, and deformation of pods.
Control methods:
Identify and cut down infected trees, burn them and replant trees with resistant hybrids.
However, agroforestry studies showed CSSV severity lowest at 54% shade cover, while yields are highest at 39% shade.
Infected farms should be replanted with resistant varieties and the replant trees should be surrounded by barrier crops, e.g. citrus, coffee.
Improved planting material varieties may need good farm management practices, e.g. shade, to produce good yields.
Research has been done on resistance breeding, mild-strain cross protection and the molecular variability of the CSSV virus has been studied.

23.2.6 Cocoa pod borer, Conopomorpha cramerella
See diagram 55.30: Conopomorpha cramerella.
Coconut pod borer, (CPB), Cocoa moth, Conopomorpha cramerella, (Class Insecta, Order Lepidoptera, Family Gracillariidae), a tiny moth, brown with bright yellow at tips of forewings, long backwards-sloping antennae.
During the day they rest on the underside of branches or leaves, but during the night they are active.
Larvae are white to green and up to 10 mm long.
Pupae are in an oval-shaped cocoon on a cocoa pod.
Tiny eggs are yellow to orange.
The pod borer larvae bore into husk of young, green cocoa pods and feed on the placentas, causing the seeds to stick together.
A common symptom of infected pods is unevenness and premature ripening.
The cocoa pod has damaged undersized seeds, hard pulp and bad flavour after fermentation process.
The larvae leave entry and exit holes in the husk of the pod.
Monitor cocoa pods for uneven ripening, tiny borer holes and larval debris on the pods, premature ripening of the pods.
Cut the pods open and examine them for tunnelling inside, damage and beans that stick together inside the pods.
The adult moths cannot fly far, but the infection can be spread from infected pods, or plant material infected with cocoa pod borer eggs, pupae or moths.
Control methods:
Regular harvest of pods and removing husks, pruning the canopy to less than 4 m, pod sleeving with plastic bags.
Insecticides Apply recommended insecticides.
Cut out alternative hosts: Pacific lychee ( Pometia pinnata), rambutan ( Nephelium lappaceum), cola ( Cola acuminata).
The black ant (Dolichoderus thoraxicus), weaver ant (Oecophylla smaragdina), and rainbow ants, Iridomyrmex cordatus have been used to control Cocoa pod borer.
These ants may be transferred from farm to farm by using nests of rolled-up leaves stuffed into plastic containers or pieces of bamboo and hung up in trees.
Other borers:
In Papua New Guinea and the Solomon Islands, two pod boring moths, Cryptophlebia encarpa and Olethreutes are minor pests of cocoa.
Eggs are laid singly on the pod surface.
The larvae hatch within 24 hours and burrow into the epicarp of the pod husk to feed.
The larvae feed for 13 to 15 days.

23.2.7 Vascular streak dieback, (VSD), Oncobasidium theobromae
See diagram 55.2.3: Dieback disease
See diagram 55.48: Vascular streak dieback.
Vascular streak dieback, (VSD), Oncobasidium theobromae, (Division Basidiomycota, Family Ceratobasidiaceae), occurs during the wet season the disease starts when leaves turn yellow and drop off, in the top branches of the tree, then spreads to other branches, then usually the tree dies.
In the nursery, protect the seedlings from VSD by covering them with plastic sheet, then fronds for shade.
Make sure the trees have enough shade.
Observe whether the leaves have brown leaf edges, or yellow leaves or leaves with light green patches between leaf veins.
These things may mean that the trees are not getting enough minerals, and they may need some fertilizers.
Control methods:
Prune off dead branches and cover the cut ends of branches with tar, pruning below the discoloured xylem, reduce shading.
Fungicides get washed away during the wet season, but the triazole fungicide Propiconazole (C15H17Cl2N3O2), may be sprayed on plants in the plant nursery.
Only a few trees may be killed by Vascular Streak Dieback, even if is common, possibly, because the Trinitario cocoa variety planted is genetically variable.

23.2.8 Brown root rot, Phellinus noxius
See diagram 55.31: Phellinus noxius sterile crust around the trunk.
1. Brown root rot, Brown tea root disease, Phellinus noxius, (Division Basiomycota, Family Hymenochaetaceae), is a fungus that attacks tree roots causing decay, yellow leaves yellow and wilt, beginning at the tips of the branches, resulting in tree death.
It is a natural component of rainforests, and can be found in commercial plantation forests, fruit orchards and urban areas.
Phellinus noxius has a wide host range and may infect oil palm, rubber, coffee, breadfruit, avocado and coconut.
2. Look for the sterile crust that grows up around the trunk from the base of infected trees, and brackets of fungus on old stumps and on shade trees.
The presence of the disease will often indicate structural damage through extensive wood decay and subsequent tree failure.
Tree death is often rapid in young trees with wilting often the first obvious symptom.
3. In older trees, decline is more gradual and the leaves turn chlorotic, followed by thinning of the crown and eventual tree death.
Internal wood decay can cause trees to fall without warning.
4. The presence of Phellinus noxius can generally be recognised by a ‘stocking’, a dark brown to black crust on the trunk with a white margin, often with clear drops of liquid, that forms on the roots and tree trunk.
When actively growing, the 'stocking' has a white advancing margin, which turns a cinnamon colour and then dark brown as it ages.
5. The disease spreads most commonly by root to root contact, but it can spread when air-borne basidiospores from the base of dead trees infect newly cut tree stumps.
6. Control methods:
The disease is difficult to control and can remain viable in the soil for many years.
Planting without removal of stumps with brackets of Phellinus may cause death of new plantings.
Control this disease by removing the entire infected tree and as much roots as possible and dispose it by composting or burning.
Once a tree is infected, there is no way to cure it, and it will die.
There is no chemical control for this disease.

23.2.9 Ceratocystis wilt of cacao, (Ceratocystis cacaofunesta)
See diagram 55.2.1: Bark canker .
Ceratocystis wilt of cacao, Mal de machete, Ceratocystis cacaofunesta, (Division Ascomycota, Family Ceratocystidaceae), attacks the trunk and branches of the cocoa tree through wounds made by insects or cutting, e.g. pod harvesting.
If a tree has the canker, the bark may have patches of darker colour.
Also, a reddish brown liquid may come out of the bark and turn a rusty brown colour when dry.
Insects live in the dying bark and may make any holes in it.
When the bark is cut away, you can see the canker.
This disease is caused by the same fungus that causes black pod.
Always put tar over a cut made when pruning a tree.
Pruning tools must be sterilized by dipping them in a 1% sodium hypochlorite solution.
Control methods:
Take all infected black pods away and destroy them, because they carry the canker spores.
In small cankers, cut away the bad bark, making a clean cut just outside the canker.

23.2.10 Cocoa weevil borer (Pantorhytes biplagiatus)
See diagram 55.2.2: Pantorhytes sp. larva.
See diagram 55.2.4: Pantorhytes sp. adult.
1. The Cocoa weevil borer, Pantorhytes biplagiatus, (P. plutus), (Order Coleoptera, Family Curculionidae), larvae bore into the wood of the trunk and main branches of the cocoa tree.
The wingless adults, about 1-5 cm long, feed mainly on the bark of young cocoa shoots, though damage is rarely economic.
They lay eggs in small cracks in the bark of the main branches of the cocoa tree.
The eggs are white, ovoid, about 2 mm long, are laid singly in crevices on the trunk, main branches, especially near the jorquette.
The eggs hatch after 2 to 3 weeks and the larvae burrow into the wood just beneath the bark, boring holes into the trunk as they grow.
The larvae have a well developed brown head and curved cream body with rows of fine hairs.
They bore into the wood 1 to 2 cm deep and feed on sap wood making tunnels or channels parallel to the surface for 8 to 12 weeks.
The larvae may make holes right through the trunk and may go around and ring-bark (girdle) the branch or trunk.
A jelly-like liquid from the damaged wood may come out of these holes.
The holes allow diseases such as bark cancer, Phytophthora palmivora and termites to infect the tree.
The larva feed for up to 9 months and then pupates beneath the bark in about 14 days.
The larvae turn into a nesting pupa, then become adult.
The newly emerged adults feed for 4 to 6 weeks before mating, after which time the female lays about 2 eggs per day during her life span of one to two years.
Cocoa weevil borer can cause a severe drop in production and a large proportion of the cocoa plantation may die.
The larvae construct a silk web mixed with brown droppings, frass, over the feeding area for protection.
So the larvae are easily detected in the tree by the presence of frass expelled from the entrance hole of the larval channel.
Remove the frass with a stiff brush and then kill the larvae by applying a solution (larval channel paint mixture), of acephate, (C4H10NO3PS) (Orphene) + white oil +, systematic fungicide Metaxyl, (C15H21NO4), onto the bark around the entrance hole.
It is difficult to kill the larvae inside tunnels with chemicals.
Cocoa trees severely infected with Pantorhytes larvae should be inspected and treated at least every two weeks.
4. Control methods:
Control by hand-picking of adult weevils, which are easily seen during the day.
This cost-effective method is popular with cocoa farmers and may be operating on a "bounty payment system".
Cocoa weevil borer can live on Eucalyptus, Terminalia, and native mulberry, Pipturus argenteus, so ask the agriculture extension officer to show you these plants so you can destroy them if they are near the cocoa plot.
When grown in coconut shade Pantorhytes populations may be low possibly, because coconuts often harbour the green tree ant Oecophylla smaragdina, which are believed to repel Pantorhytes.
Cocoa grown beneath the shade trees, e.g. Gliricidia, are often badly damaged by Pantorhytes.
Gliricidia, (Gliricidia sepium), Fabaceae
See 9.34.2 The yellow crazy ant, Anoplolepsis longipes, has been used for biological control of Pantorhytes.

23.2.11 Coconut bug, coconut nutfall bug, Amblypelta cocophaga
See diagram 55.38: Amblypelta.
Coconut bug, Coconut nutfall bug, Pod sucking bug, Amblypelta cocophaga, (Order Hemiptera, Family Coreidae), adults and nymphs suck sap from pods and can cause pod spots and distortions on cocoa.
Amblypelta theobromae and Amblypelta cocophaga adults and nymphs suck sap from pods and can cause large crop losses.
The body is about 20 mm long, the legs are pale green, while the wings are pale brown.
Females lay eggs on or near the host plant and nymphs hatch a few days later.
They are dark brown with long legs and antennae and they look like adults without wings.
Nymphs feed in the same way as adults, and on the same plants using needle-like mouthparts.
It is not known if nymphs inject poison.
Wings develop when nymphs become adult, 3-4 weeks after emerging from the egg.
They are brown or green bugs about 2 cm long.
They have very long feelers, but in the young bugs the feelers are thick.
The young and old bugs feed on cocoa pods and young shoots.
They suck juices up through long thin feeding tubes.
If they feed on young pods, the whole pod may be spoiled, and young shoots may be killed.
These bugs also attack coconut trees and make the young nuts fall off the tree.
Control methods:
Spray the pods with the same spray used to kill capsids.
Insecticides Apply recommended insecticides.
The fire ant, Wasmannia auropuntata and the green tree ant Oecophylla smaragdina, can protect the cocoa tree against Amblypelta, but yellow crazy ant, Anoplolepsis longipes may chase them away.

23.2.12 Termites
See diagram 55.1.4: Termites.
The termites or "white ants" are ants that live by eating holes in wood.
Wood-eating termites, (Isoptera: Kalotennitidae), adults and nymphs chew wood inside the tree.
They may weaken a branch or a trunk so much that it falls over.
Termites first enter the tree via dead branches and then make their nest in the living wood and feed on it.
The tree canopy is reduced, production falls, branches die and eventually the tree is killed.
It is often hard to tell whether the termites are in a tree, because they make holes just under the bark and there may be no signs outside.
Control:
Termite infestations can be prevented to some extent by pruning dead branches from the tree.
If an attack is found, the branch can be cut off close to the main branch.
If a nest is found, it can be opened a little and a bottle full of weak chlordane (0.2%), mixture poured into it.
Slowly pour chlorpyrifos, (C9H11Cl3NO3PS), solution at the base of each transplanted seedling.
Insecticides Apply recommended insecticides.
Termites are easily controlled by exposing part of the nest and pouring a dilute solution of insecticide into it.
The newer pyrethroids give a good kill and are safe to use.
The giant termite, Neotermes papuana (Class Insecta, Order Blattodea, Family Kalotermitidae), is particularly damaging.
It does not construct covered runways on the tree, but the location of the nest is indicated by a water-soaked appearance on the bark.
Some shade trees are also attacked by termites and so these must also be inspected regularly and treated.

23.2.13 Giant African snail (GAS) (Achatina fulica)
See diagram 55.36: Giant African snail.
Giant African snail
The Giant African snail, (GAS), Achatina fulica, (Class Gastropoda, Family Achatinidae), can kill young cocoa seedlings and damage cocoa trees.
It can feed on leaves and tubers of many types of crops.
It searches for food at night, especially after rain, and hides in the soil during daytime.
During the day they hide in moist situations, e.g. under the leaves of broad-leaved low-growing plants. The eggs are 5 mm diameter, round and white are usually found in batches of about 200 eggs just beneath the soil surface.
The eggs hatch within 15 days after laying.
It was introduced from East Africa and is now established in the Solomon Islands.
It can be easily transported between countries in containers, machinery and empty bottles.
After it has become established, it is extremely difficult to eradicate.
Villagers should collect the snails and kill them by burning or immersing in sea water.
Clear rubbish and weeds in infected areas to reduce breeding places.
Do not bring planting materials from infected areas to places where the snail is not present.
Control methods:
The best way to control Giant African Snail is to eat them.
The snail can be controlled with chemical baits, e.g. Blitzem, Esbit, Canned Heat (metaldehyde), fuel tablets and snail bait, mixed with sawdust and cement.
However, but baits may be dangerous if eaten by students or domestic animals.
See: Metaldehyde.

23.2.14 Thread blight diseases (Marasmius spp.)
See diagram 55.39: Marasmius sp.
Thread blight diseases occur in poorly managed, over-shaded cocoa farms.
Horsehair fungus, Marasmius crinis-equi, (Division Basidiomycota, Family Marasmiaceae), occurs on cocoa, tea, mango and black pepper.
It appears as smooth brown to black hairs or threads like horsehair, about one tenth of a mm in diameter.
The threads travel along branches and over leaves.
The leaves break from the branches and remain suspended in place by the horsehair threads.
The fungus does not cause a disease, but just grows over the leaves, but does not infect them.
When the leaves break naturally from the stems, the dead leaves are held in place by strands of the fungus.
Many dead leaves remain hanging on a branch in the canopy.
White thread blight, Marasmius scandens (Division Basidiomycota, Family Marasmiaceae), forms a network of mycelial strands across the leaves which break off the tree and fall.
The symptoms are visible to the naked eye, when the leaves are wet so it is a disease of poor tree maintenance.
It appears as a web of white mycelia and bundles of fungal threads growing over branches and dead leaves.
The fungal threads stick the leaves to the branches.
Control methods:
Prune off the infected leaves and branches, take them away from the cocoa plot and burn them.
Use regular pruning to maintain light shade and an open cocoa canopy.
Prune out infected branches and burn them.
Apply copper fungicides to control serious infections.
Thread blight diseases do not cause disease on the cocoa tree, so just ignore them if you don't mind if your farm is poorly managed.

23.2.15 Longicorn stem borers
Longicorn beetles, (long antennas beetles), e.g. Glenea lefebueri, (Class Insecta, Order Coleoptera, Family Cerambycidae)
See diagram 55.1.4: Longicorn beetles.
See diagram 55.23: Glenea larva.
Wood boring longicorn beetle larvae bore into wood near the trunk base and main branches.
They are associated with poorly managed cocoa under heavy shade or near forests.
These pests are big beetles with "square shoulders" and very long antennae.
The beetles are either bright yellow or bright blue and do little damage.
The larvae of these beetles are pale yellow in colour and have strong jaws.
The beetles lay their eggs in cracks in the bark of the trunk.
The larvae hatch out and eat holes in the soft part of the trunk, just under the bark, in the phloem cambium region.
The trunk may becme girdles, (ring barked), and die.
Signs of this grub may be seen as lumps of wood chips stuck together in rusty coloured lumps, called frass.
These are pushed out and breathing holes made by the larvae.
The fungus causing the tree canker may get into the tree through these holes.
Control methods:
Be sure that they are economically important before any control, because control is very difficult.
Removal of climbing weeds and heavy shade.
Insecticides Apply recommended insecticides.
The way to kill these larvae is to open some holes and pour in an insecticide.
This can be made up by mixing together: 12 litre of Lebaycid, 4 litres of white oil, 12 litres of water 16 mL wetting agent.
Zeuzera coffeae bores into small cocoa plants, causing branches to snap off.
See diagram 55.24: Zeuzera larva.
Zeuzera moths (Order Lepidoptera, Family Cossidae), larvae bore into wood of trunk and main branches.
The damage caused by Longicorn beetles may lead to infection from other diseases, e.g. Black pod.
For new plantings of resistant varieties, plant a 15 m wide barrier crop of an approved food crop, e.g. sweet potato.
Paint cut wood to stop more infection with a channel paint: 30ml Chlorpyrifos + 250ml White Oil + 15g Ridomil Plus + 700ml water.
Tip boring Oxymagis (Order Coleoptera, Family Cerambycidae), larvae bore into terminal branches.

23.2.16 Cacao webworm, Pansepta teleturga
Cacao webworm, Pansepta teleturga, (Order Lepidoptera, Family Xyloryctidae), trees are damaged by larvae channelling into branches, restricting the growth of young trees.
The larvae are most damaging on young trees when they bore into or ring bark the main branches.
Large areas may suffer from severe tip dieback, including main branches, canopy degradation and crop loss.
Control methods:
There is no economic control recommendation for Cacao webworm on mature trees apart from keeping a population of Crazy ants.
It was usually only a problem on lightly-shaded cocoa, but recently it has been reported throughout well-shaded plantings.

23.2.17 Pink disease, (Erythricium salmonicolor)
See diagram 55.2.3: Pink disease.
Pink disease, (Erythricium salmonicolor), (Division Basidiomycota, Family Corticiaceae) attacks the branches of cocoa trees.
It also attacks branches of other trees like coffee, citrus or rubber trees.
The first sign is when fine white threads of fungus are seen on a branch.
Later the fungus forms a pink crust over the branch.
By the time the leaves drop off the tree, the branch will soon die.
Control methods:
Cut off the diseased branches making the cuts 45 cm below the bad part.
Take the bad branches away and burn them.
Put some tar or other chemical fungicide over the cut you have made on the tree.

23.2.18 Rodents, rats
See diagram 55.1.7: Poison baits for rats.
See diagram 55.49: Pacific rats.
The rats may do much damage to cocoa pods, because they eat holes in the outside of the pods so they can eat the soft part inside.
Control methods:
Put wax blocks containing brodifacoum or warfarin into bamboo tubes and tie these on to the branches of the tree, out of reach of children and farm animals.
Before using brodifacoum or warfarin, ask an agriculture extension officer for permission to use these chemicals.
Crazy ants, Get some yellow crazy ants (Anoplolepis gracilipes), which will keep the rats away.
Whatever you do to control rodents, it is essential that measures are carried out on an area wide basis, one farmer trying to control rats is useless, and remember that rats are smart and may show "bait-shyness".

23.2.19 Swarming leaf beetle, Rhyparida spp.
See diagram 55.32: Rhyparida.
Swarming leaf beetle, Rhyparida spp., (Order Coleoptera, Family Chrysomelidae), feeds on the flush leaves of cocoa can build up rapidly and cause extensive defoliation.
They are about 3-5 mm long, shiny brown or black and they appear in swarms.
There are many species of Rhyparida distributed throughout Papua New Guinea.
Eggs are laid on the ground and the larvae feed on plant roots.
Pupation also occurs in the ground and the life cycle takes about 6 weeks.
They prefer new leaves and young shoots and may defoliate the tops of cocoa trees, but the older trees usually recover from the infection.
Defoliation can be prolonged and particularly damaging when associated with dry weather.
Control methods:
Rhyparid beetles appear to have few natural enemies except for crazy ants which live on the branches, not the leaves where the phyparid beetles feed.
Insecticides Apply recommended insecticides.
It is often necessary therefore to control Rhyparida on cocoa trees up to about 2 years old by using insecticides.

23.2.20 Thread blight (Corticium incisum.
See diagram 55.1.1: Thread blight.
Thread blight, Corticium incisum, (Phylum Basiomycota, Family Corticiaceae), can be seen easily, because the leaves have fungus threads growing thickly over them.
Sometimes the threads are white and sometimes they are a dark colour.
The threads are quite thick.
This disease makes the leaves die and go brown.
Control methods:
Cut out the diseased branches and burn them.

23.2.21 Weeds, Mistletoe
See diagram 55.1.0: Weeding.
1. Do hand weeding within a metre circle in a ring around the young cocoa plants to avoid any damage to them with knives or herbicides.
Pile the cut weeds around a tree to make a mulch.
Do the weeding three to four times in the year during the establishment phase before the canopy closes by manual slashing along the tree rows or around young plants.
Less weeding is needed when the shade trees are well established, the cocoa canopies are touching and leaf mulch inhibits weed growth, so only woody weeds must be removed.
However, breaks in the canopy or equipment access paths allow weeds to grow again.
Use herbicides, e.g. "Gramoxone" or "Roundup" very carefully to avoid damaging the young plants with spray drift.
For the efficient application of herbicides, plant the cocoa trees in lines.
2. Weeds affect young cocoa and mistletoes affect mature trees.
See diagram 55.33: Mistletoe.
Mistletoe are parasitic flowering plants dispersed by birds, which kill branches farthest away from the point of attachment.
Phragmanthera species of mistletoe may be the main production limiting factor of cocoa in West Africa.
Plants planted in rows show a higher rate of infection than plants planted randomly.
The mistletoe, Phragmanthera incana, (Family Loranthaceae) and Loranthus bengwensis, (Tapinanthus bangwensis) grows on cocoa (Theobroma cacao), kolanut (Cola nitida), citrus, coffee, and bush mango (Irvingia gabonensis).
Control methods:
Control is by pruning of the infected branches, using a machete or a long stem hook.
However, mistletoe is a folk medicine and the host of many useful insects.

23.2.23 Cocoa mealybugs
See diagram 55.34 Mealybugs
See diagram 55.37: Mealybug
Cocoa mealy bugs, (Order Hemiptera, Family Pseudococcidae), adults and nymphs suck sap from shoots, pods and flowers.
Cocoa mealybug, Exallomochlus hispidus, (Hemiptera, Pseudococcidae) can attack cocoa and mangosteen, kabocha squash, soursop, guava and many other host plants.
Cacao mealybug, Coffee mealybug, Oriental cacao mealybug, Lilac mealybug, Planococcus lilacinus, can attack cocoa, coffee, tamarind, custard apple, coconut, citrus.
Also, Citrus mealybug, Planococcus citri, Pacific mealybug, Planococcus minor, West African cocoa mealybug, Planococcoides njalensis, Yam mealybug, Planococcus pacificus.
Mealybugs can damage seedlings, cherelles and shoots by penetrating the phloem to take out sap with their needle-like mouthparts.
During dry weather, their numbers can sometimes increase to damaging levels, causing distortion of the growing shoot of young plants, white powdery masses of insects at the shoot tip and deforming young pods.
Mealybugs can be the vector of Cocoa swollen shoot virus.
Mealybugs, like aphids, secrete a sugar sap from phloem of the cocoa tree called honeydew onto the surface of the plant. Crazy ants feed on the honeydew and protect the mealy bugs from enemy insects. The honeydew is a medium for 'sooty mould' fungi, which impairs photosynthesis and blackens cocoa pods.
The adult female has a dome-shaped, oval body, which looks white and ‘mealy’, because of a thick covering of white wax threads.
The adult male has a different thin body.
Nymphs are similar in colour and shape to the female.
The adult female lays eggs with a protective layer of white wax threads on the underside of leaves, on pods and on flower cushions.
Nymphs hatch out and feed in the same way as the adults.
Control methods:
Remove chupons, a favourite food of mealybugs.
Remove plants which harbour ants, because honeydew is eaten by ants, including Yellow crazy ants.
Control with potassium based soaps, e.g. Alata Samina, (Raw African Black Soap), an extract from the cocoa plant.
Spray malathion and white oil (30 ml Malathion 50, 0.15%, 100 ml white oil, 2 ml surfactant, 50 ml sticker, in 10 litre water).

23.2.24 Broad mite (Polyphagotarsonemus latus)
See diagram 55.47: Broad mite.
Broad mites cannot be seen with the unaided eye.
It feeds on the lower surface of young, soft leaves, rolls the cocoa leaves, which become yellow then bronze with curved veins, and brittle.
The flowers fall or deformed and discoloured fruits form.
Control methods:
Clear crop debris and burn it.
Avoiding plants infected with mites, e.g. tomato.
Use pesticides, e.g. lime sulfur, (CaSx), or [Abamectin (C48H72O14) + vegetable oil].

23.2.25 Grey weevils, (Hypotactus ruralis)
Shoot chewing Grey weevils (Order Coleoptera, Family Curculionidae), adults chew bark on shoots of young cocoa and terminal branch\ feeding.
The name "Grey weevil" refers to a group of genera, mainly Hypotactus ruralis and also species of Paratactus, Cyphopus and Oribius.
Hypotactus ruralis adults have strong, light grey bodies with a weevil snout, 2 antennae, light grey legs, but no wings.
Paratactus adults are dark grey with 4 white patches on the thorax.
Oribius adults may be light to dark grey.
Cyphopus adults are light grey and have 2 small swellings on the back of its body.
All these weevil adults are similar in size to Hypotactus ruralis, but Exopthalmida adults are much larger than the others, about 15 mm long.
The oval-shaped eggs are laid at the base of plant stems, or on blades of grass that are then folded over the eggs.
The eggs hatch, forming larvae that burrow into the soil and feed on plant roots.
Grey Weevil larvae of are cream-coloured, C-shaped grubs with a dark, red-brown head and jaws.
They move close to the soil surface for the pupal stage that is similar to the larva in colour and size, and lasts 13 days.
Adult Grey weevils can live for more than 6 months, preferring light sunny exposed places with well-drained soil.
They do most damage in dry weather on under-shaded blocks with poor soil and lots of weed.
Grey weevils cause ‘shot-hole’ damage to leaves in nurseries and chewing damage to the semi-hardened bark and petioles of young shoots.
They attack lightly-shaded young cocoa and Gliricidia, stunting and sometimes killing the plants.
The attacks commonly occur at the early planting stage, at the time of 1st to 10th leaf flush, and subside when the cocoa trees are about 18 months old, when they are stronger and better shaded.
Grey weevils can be a serious problem on cocoa planted under coconuts.
Control methods:
Weeds can attract leaf eating insects such as Grey weevils that can damage the cocoa plants, so spraying weeds with herbicides that kill their roots deprive the weevils of roots on which they feed.
Locate nurseries well away from old cocoa and control weeds in the nursery.
Insecticides Apply recommended insecticides.

23.2.26 Cocoa root chafer (Dermolepida spp.)
See diagram 55.52: Root chafer larva.
Root chewing Chafer beetles (Order Coleoptera, Family Melolonthinae), larvae chew roots of young trees.
Cocoa root chafers, (Dermolepida spp.), (Coleoptera, Scarabaeidae) is a serious pest of young cocoa up to 2 years old, that feed on the roots in old food gardens, e.g. taro, and can kill the plant if eat through the tap root.
The adult beetles feed on the leaves of cocoa and banana, but do little damage.
The females lay their eggs deep in soil near the root of a cocoa, near to where they emerged from the pupae, so the population increases there.
After about 3 weeks the eggs hatch to form larvae to feed on small roots, then bigger roots as the larvae grow to up to 4 cm long.
The larvae do little damage to mature plants.
The larvae pupate in the soil.
Cocoa root chafers feed on common food crops, so they may be common near old food gardens.
Control methods:
Do not construct a cocoa plant nursery on or near old food gardens.
Insecticides Apply recommended insecticides.
Put chlorpyrifos granules in the soil around the roots when planting out or in the planting hole before planting out if damage from root chafer is expected.

23.2.27 Leaf-eating caterpillars
Leaf eating caterpillars (Order Lepidoptera, Family Limacodidae) larvae eat both young and mature leaves.
Leaf-eating caterpillars cause uneven eating of soft young leaves.
Severe defoliation by caterpillars slows growth of young trees and causes yield decline in mature trees.
Psyllids may deposit large numbers of eggs in terminal buds resulting in desiccation and death of the bud and growth retardation in the shoots of young cocoa trees
Control methods: Spray caterpillars and psyllids with acephate, (C4H10NO3PS) + surfactant, in water.
See diagram 55.35: Psyllids.
Insecticides Apply recommended insecticides.

26.0 Cocoa news in the Solomon Islands
Agrikalsa Nius, November-December - 2020 (Edited for this website)
Research work to ascertain cocoa varieties in SI piloted
The genetic background of cocoa is more complicated than the simple designations of Amelonado (Forestero type), Criollo and their hybrid Trinitario.
In the last decade with the advent of sophisticated DNA “finger printing” techniques, cocoa researches report that cocoa originally consisted of ten unique family groups in its centre of origin, Central and South America.
Over the last several hundred years, with the dispersal of seed, budwood and plants to other tropical production regions the genetics of cocoa has mixed.
The new DNA techniques can determine the percentage of the 10 original family groups in a sample.
The analysis of sampling carried out by MAL in Makira Province has shown that although the bulk of cocoa sampled has a predominately Amelonado background there are examples where the Criollo component is as high as 18%.
The information can be used to make selections (clonal material) for regional testing where yield and the potential for fine flavour types are identified.
This is determined by DNA extraction and genotyping.
DNA extraction is done in Queensland, Australia.
Further to that, the extracted DNA are sent to the United States Department of Agriculture (USDA) Agricultural Research Centre (ARS), Maryland, USA for genotyping.
Genetics of cocoa and the post-harvest practices influence the type of flavour which the chocolate makers are looking for.
The Australian Government through the Australian Centre for International Agricultural Research (ACIAR) funded the project lead by the Department of Agriculture and Fisheries, Queensland.

Agrikalsa Nius, May-June - 2021 (Edited for this website)
Chale & Uzamba farmers trained on cocoa grafting for better production
Training on cocoa grafting was conducted for Chale and Uzamba Participatory Action Research (PAR) farmers in the Western Province.
Research Officer, Raymond Vava said the trainings are critical to ensure farmers get the necessary knowledge on cocoa grafting to increase production.
He further said that on-farm testing of selected imported cocoa genetic materials through grafting on PAR farms is part of the national cocoa genetic material improvement program which aims at improving cocoa planting materials for cocoa farmers to increase on-farm productivity per tree.
PAR farmers in both sites visited were trained on how to do top grafting on young cocoa seedlings and chupons as well as side grafting on mature cocoa trees.
The grafting training was conducted inside the cocoa plantation and performed on chupons and some seedlings that were prepared for the training.
He said from the training it is anticipated that farmers would apply the acquired grafting skills and quickly adapt and spread the good planting materials within the farm to increase production per tree.
Some of the clones were side grafted onto mature trees while some were top grafted on seedlings.
A new cocoa nursery was purposely build to raise rootstocks for grafting of potential materials to establish a small cocoa observation plot which can also act as a source of budwoods for nearby cocoa farmers.
Around 400 polybags were filled with soil and were sown with cocoa seeds for raising of rootstocks.
Grafting has a lot of significance, but in simple terms it means to join two living trees from the same family into one by tying a shoot or a bud with a standing tree.
It has so many benefits and one particular gain is it improve yield performance of a tree and retain the desirable genetic characteristics of a mother tree.

Preface
Before teaching this project, discuss the content of the lessons with an agriculture extension officer, and get advice on planting material, planting distances.
If you cannot control insects by hand-picking, the agriculture field officer may recommend use of a pesticide.
International authorities have a list of the active ingredients in pesticides that must not be used for cocoa, because high chemical residue levels have been found in imported cocoa produce to the EU and Japan.
Cocoa growers are strongly advised to stop using any products on this list, but use recommended substitutes.
When using a pesticide, wear protective clothing and follow the instructions on the product label - dosage, application timing, pre-harvest interval.
All insect sprays are dangerous.
You must be able to demonstrate the safe use of sprays.
Do not get the spray onto your hands.
Do not breathe in the spray.
Wash your hands well after using spray.
Keep the spray container in a safe place under lock and key.
Spray on a day of no wind, but if you must spray when there is a wind, spray down wind.
Make sure the spray does not blow on other people.