In the commercial cocoa plantation, proper plant protection is essential to get optimum profits. And you must control the cocoa pests and diseases properly. This article includes the detailed cocoa pests and diseases management guide for sustainable farming.
Generally, proper management of pests and diseases help to reduce the damage. Hence, it ensures better yield and profitability. So, in initiating a commercial cocoa plantation business, you must have a clear conception about the potential harmful pests and diseases and control methods. Actually, there are over 1500 insects in different cocoa growing countries.
List of Potential Cocoa Pests & Diseases
#1. Black Pod Disease (Phytophthora palmivora)
Actually, this is the most important disease of cocoa in all cocoa growing regions. And it becomes severe in the rainy season. Pods of all age groups are susceptible to this disease. Generally, circular brown spots appear. And it enlarges concentrically and evenly covering the whole pod surface. Ultimately, the color of pods become dark brown or black. In immature pods, beans remain partly or wholly unaffected.
First of all, you must remove the infected pods as and when they appear on the tree. Additionally, provision of good drainage and aeration in the garden is important during the monsoon period. Also, you can spray Bordeaux mixture 1% with adhesive before the onset of monsoon immediately after removing infected pods.
#2. Vascular-streak Die-Back (Oncobasidium theobromae)
Generally, this disease occurs on the main stem of seedlings or on a branch of an older tree. The first symptom is yellowing of one leaf. Usually, the second or third behind the growing tip with the development of green spots or islets scattered over the yellow background. Generally, the infected leaves fall off within a few days and subsequently leaves above and below it, turn yellow and shed. It results in a distinctive situation where the youngest and the oldest leaves on a branch are still present while all the middle ones have fallen. Leaf scars from fall-off of chlorotic leaves are sometimes covered by a white, loosely adherent fruiting body of the fungus. If the diseased stem is split longitudinally, xylem appears as discolored brown streaks.
You may find effective pruning the plants 30 cm below the discoloration of vascular tissue. Also, you can consider the application of Bordeaux mixture 1% at 45 days interval from the onset of monsoon to prevent its spread.
Fan branches and small twigs are generally infested by the pathogen. It is severe during heavy rains. The first indication of the disease is the death of branch. generally, you can notice characteristic pinkish encrustation of fruiting bodies of the fungus on the bark of infected branches. Finally, it turns greyish-white. Before the appearance of visible external symptoms, many fine, white, silky mycelia already spread over the surface. And into the cortex of the bark leading to defoliation and death of distal part of the branch.
first of all, remove and destroy all the infected and dried branches. Apply Bordeaux paste at the fork region and at the cut ends of twigs. Additionally, spray with Bordeaux mixture 1% before the onset of monsoon.
#3. Charcol Pod Rot (Botryodiplodia theobromae)
Actually, this disease is characterized by the formation of water-soaked lesions on pods either at the tip or stalk end at all stages of maturity. Initially, the lesion is chocolate-brown and then dark. In due course, complete pod develops a black sooty appearance as a result of the formation of dark-colored spores of the fungus all over the pod surface.
Remove all the infected pods and spray with Bordeaux mixture 1%.
#4. Colletotrichum Pad Rot (Colletotrichum gleosporioides)
Generally, the initial symptoms appear as chlorotic spots on the surface of the pods. And it later turns to dark brown and necrotic. The spots enlarge in a circular manner surrounded by a prominent chlorotic yellow halo. Fully developed spots are dark brown and depressed in nature. It later coalesces to cover large areas on the surface of the pod. Additionally, pink-colored fructifications of the fungus develop on the necrotic spots. In advance stage, the pods dry and remain as a mummified structure on the tree.
Remove the infected pods and spray with captafol 0.2% or Bordeaux mixture 1%.
#5. Red Borer (Zeuzera coffeae)
Larvae burrow into the main stem of young plants and fan shoots of older trees. It causes drying up.
Prune off and burn affected fan shoots. Also, you can spray Carbaryl 0.1% on the main stems of young plants as a prophylactic measure.
#6. Tea Mosquito (Helopeltis Antonii)
The bugs mainly attack the pods. Circular water-soaked spots develop on the infested pods, around the feeding punctures. and it later turns pitch black in color, causing deformity of the fruits.
You can control the pest by spraying Endosulfan 0.05%.
#7. Mealy Bugs (Planococcus lilacinus)
The bugs occur in Cherelles, developing pods and shoots and desap the tissues leading to the formation of scabs. Generally, this pest occurs throughout the year but attains peak population levels during July-October.
You can control it by spot application of Quinalphos 0.025% or Phosalone 0.1%.
#8. Grey Weevil ( Myltocerus spp)
A number of species of Myltocerus weevils infest cocoa. The attack is severe on young plants. Additionally, the peak period of infestation occurs during July to September. The adults occur in groups on the underside of leaves and feed on the green matter leaving the veins intact.
Spray Carbaryl 0.1% or Fenthion 0.05% on the under the surface of foliage twice a year during May and September.
#9. Aphids (Toxoptera aurantii)
Generally, the colonies of pink aphids infest flower stalks, tender leaves, and shoots. On leaves, aphids are confined to the lower surface.
In this case, chemical control is not essential. You must collect and destroy the severely affected plants part immediately.
#10. Cock-chaffer Beetle (Leucopholis spp)
The grubs feed on surface roots of young cocoa plants and sometimes on grown-up plants causing wilting. Generally, the infestation is more frequent in the coconut-cocoa intercropping situation. Because the same pest attacks coconut as well.
You can protect the seedlings by application of Carbaryl 10% DP @ 10 gm per pit. Also, you can drench the grown-up plants with the wettable formulation of Carbaryl 0.1%.
#11. Red Banded Thrips
Adults and nymphs of the thrips appear in colonies on the undersurface of leaves and pods. They feed on fluid excluding from the scrapped tissues. Generally, infested leaves turn pale-green to pale-brown and dry up later.
You can control this by the application of Quinalphos 0.05%, Phosalone or Fenthion.
#12. Storage Cocoa Pests
When you store the cocoa beans for more than 2 months, you may find damage beans. There are several cocoa pests and insects behind this damage. However, the rice meal moth (Corcyron Cephalonica) is the most important one. The larvae of the moth feed on the internal contents of the beans and construct silken galleries using frass and broken down particles of the beans.
You can mix the cocoa beans with neem leaves for a long-term storage @ 2% by weight. Generally, it helps to protect the beans up to 6 months.
#13. Non-insect Cocoa Pests
Stripped squirrels and rats cut irregular holes on walls of maturing pods and extract the contents completely. Additionally, they feed on mucilaginous pulp around beans.
Considerably, you can reduce the damage by harvesting the pods at right stage when burrows start bronzing. Also, poison baiting with Fumarian bars is quite useful.
#14. Civet Cat (Paradoxus hermaphoditus)
They gnaw holes on the pods, bite and break the husk. The civets swallow the beans and as such no trace of beans will be visible under the tree. Instead, piles of defecated beans are seen scattered around the farm.
Generally, you can control the civet cats by poison baiting of ripe banana with Carbufuran.
#15. Physiological Disorder
Actually, Cherelle wilts is a physiological disorder characterized by drying and wilting of young pods. And wilted pods remain attached to the tree. Competition for carbohydrates when the tree is overloaded with pods and mineral nutrients are major causes.
You can control this situation by applying the right nutrients and fertilizer according to the soil test report.
Here in this article, we include the most harmful cocoa pests, insects, diseases and other threats that may occur during plantation. We hope the symptoms and control guide will help you in taking the most potential plant protection measures.