Machete Technology: What Small Cocoa Farmers Need!
B. K. Matlick, Project Consultant
American Cocoa Research Institute
7900 Westpark Drive
McLean, Virginia, 22102
Numerous outbreaks of CPB, the cocoa pod borer (Conopomorpha cramerella Snellen) have occurred in Indonesia following the cocoa expansion in the late 1980's and early 1990's. In early 1997 CPB was officially confirmed in 42,864 ha of approximately 450,000 ha total planted to cocoa. The official government reports are delayed by six months to a year. By now, March 1998, I estimate that up to 100,000 ha or approximately 20% of all cocoa in Indonesia are infested with CPB. There is no scientific reason not to believe that CPB will continue to spread and infect all of Indonesian cocoa. Losses could exceed $100M, almost all too small farmers. The infestation spread rate varies from province to province and seems to be dependent on the intensity of the plantings and local weather conditions. The estimated losses in dollars due to CPB will approach $20 million in 1998. Realistically if we had hard up to date data I believe that the loss in 1998 in Sulawesi and Kalimantan alone in 1998 would exceed $25M.
Conopomorpha cramerella, the pod borer (CPB), also known as the cocoa moth is the most important insect pest of cocoa throughout South East Asia. It has been the single most important limiting factor in cocoa production in Indonesia, Malaysia and the Philippines in this century. The cocoa pod borer causes the losses of cocoa by boring in the placental tissues and the wall of the pod, disrupting the development of the beans. Moths lay their eggs on the surface of the unripe pods; larvae emerge and tunnel to the center of the pod where they feed for about 14-18 days before chewing their way out of the pod to pupate. The feeding results in pods that may ripen prematurely, with small, flat beans, often stuck together in a mass of dried mucilage. The beans from seriously infested pods are completely unusable and in heavy infestation over half the potential crop can be lost. In light infestations there may be no loss or a very slight loss (5%-10%), but control efforts may be needed to prevent higher infestation from developing. CPB occurs only in South East Asia and the Western Pacific. Cocoa is not the original host, since it has been introduced into the region to which the moth is restricted. It is a pest in addition to cocoa of rambutan, Kola and nam-nam. After the appearance of CPB at Manado in the 1840's the cocoa industry in North Sulawesi declined rapidly, (Toxopeus, Gieserger, 1983). The industry began to move elsewhere, to the Philippines and to Java. Long distance movement of the CPB must almost certainly have taken place through the movement of infested pods, as there is no indication that moths can fly long distances. About 1880 cocoa was introduced into Central Java on a plantation scale to replace coffee (van Hall, 1949). CPB infestation soon appeared in these areas. The CPB appeared in Sabah, East Malaysia in 1980. It is possible that it was introduced with pods brought from Indonesia or the Philippines. A similar introduction may have occurred in West Malaysia prior to the discovery of CPB in 1986. However in both cases, it is possible that there were local adaptations of rambutan or nam-nam feeders to cocoa. The infestation in Sabah spread readily from Tawau across the entire state during a three-year period. The initial infestation discovered in West Malaysia was contained for several years, thanks to vigorous quarantine efforts, unfortunately other scattered outbreaks began to appear and it was not possible to extend the vigorous containment efforts to a wider area.
Previous research and control methods
There have been four (4) main periods of research on CPB during this century:
- Primary research on its life cycle and the original development of cultural control methods in Java between 1900 and 1925.
- A phase of insecticide control trials in the mid to late 1950's in Indonesia.
- A major campaign on all aspects of ecology and control in Malaysia from 1980 to 1988.
- Occasional interest in specific control aspects since 1988. (ASKINDO-ACRI Project)
The early research in Java involved mainly two entomologists, Zehntner and Roepke. Zehnter provided the original description of the species and some early observations on the life cycle and the origin of the pest. Zehntner developed the first reasonable practical control method, rampasan (a classic form of control that disrupts the life cycle of the pest by removing all pods of an age susceptible to egg laying from the field for about six weeks). Various of the Dutch entomologists speculated on other potential forms of control, from the rearing of black ants (Dolichoderus spp.) as predators to hosts plant resistance based on smooth skinned varieties. The effectiveness of these ideas were limited and in part due to extensive CPB attack, the cocoa industry in Indonesia declined after the 1920's and research stopped.
During the 1950's numerous trials were conducted in Indonesia on insecticide control, using cover sprays of broad-spectrum organochlorine insecticides. Initial results appeared to be promising for a control, but on at least one estate in Java over 1000ha's of cocoa had to be destroyed in the late 1950's (after five years of general insecticide application) due to outbreaks of stem and branch bores, which were no longer adequately controlled by their natural enemies.
With the discovery of CPB in Sabah, East Malaysia in 1980, and subsequently in Malacca and the rest of Peninsular Malaysia in 1986, a major research and control effort was undertaken. This was the most important period of research on CPB and most aspects of its biology; ecology and control were explored in several parallel programs. Day, Mumford, Lim, Ho and others observed most aspects of the life history and behavior of CPB during this period, which provided the basis for a series of potential control methods. The research conclusions can best be described in relation to six groups of CPB control methods:
1. Rampasan and harvesting
2. Insecticide spraying
3. Parasite manipulation
4. Host plant resistance
5. Pheromone trapping
Cultural control (rampasan; harvesting)
Mumford observed in 1980 that there was a strong relationship between harvesting practice and infestation of CPB. He showed that the great majority of CPB larvae emerge from cocoa pods after they become ripe, and that if pods are picked at the earliest stage of ripeness (just as they begin to show yellow) then most (almost 90%) larvae will still be inside the pods. If pods are broken quickly and the husks destroyed larval mortality will be very high and a good degree of control may be achieved. Ideally such harvesting should be continued regularly throughout the year to prevent CPB populations growing. Complete, frequent, regular harvesting (CFRH) is to some extent an extension of the principle of ranpasan but aimed at larval emergence rather than oviposition. The greatest effect of (CFRH) is likely to be gained if it is done during the low crop period thorough the first half of the rising crop.
Observations in the 1950's and 1960's showed that cocoa in southeast Asia could not survive continuous blanket sprays of broad spectrum insecticide, because of destructive outbreaks of secondary pests freed from their normal control by natural predator and parasites (Conway, 1973; Toxopeus and Giesberger, 1983). The first improvements in the prospects for spraying occurred in 1981 with the observations by Day and Mumford that adult moths rest by day on the underside of lower branches in the cocoa. This provides an ideal site for selective spraying. Relatively small amounts of contact insecticides (either pyrethroid or carbamate), applied to these resting sites during the low crop period kept CPB populations below economic levels during the subsequent peak pod production periods. Sprays applied at peak pod periods had little effect on infestations in the several following months.
The large black ant (Dolichoderus sp.) has been demonstrated by Dr. Khoo Khay Chong, Universiti Pertania Malaysia, to control CPB in controlled experiments in Peninsular Malaysia, however attempts to reproduce the same control in Sabah failed. This failure may have been that the same species of Dolichoderus was not found in Sabah or that due to many years of heavy chemical spraying micro amounts of residual chemicals prevented the ants from thriving. Low levels of research continue in this area. Control by egg parasites had originally been dismissed by Waage and Mumford, however, considerable effort by Lim and hi colleagues demonstrated the presence of a parasitic wasp (Trichogrammatordia SP) in Sabah (Lim and Chong, 1987). An intensive program of rearing these wasps on an alternative host in laboratories and commercial breeding rooms and released them into the field gives good levels of control at about 25,000 wasps/ha/day/. Research continues by the Malaysian Cocoa Board (MCB) assisted by the American cocoa Research Institute (ACRI) to develop rearing and release methods that will be economically competitive with current control systems.
Host plant resistance
Early Dutch interest in host plant resistance focused on the surface of the pod. Day found no differences in egg laying on different cultivators, but very considerable differences in larvae mortality inside pods with either thicker or harder stony endocarp layers in the pod wall. Laval survival was as much as 10 times greater in soft/thin walled cultivars (Day, 1985). Azhar and Lim (1987), studied several dozen cultivators in seed gardens and concluded that the hardness of the schlerolic layer was the important factor. Sime Darby (Plantation Company) followed up these observations by planting a block of particularly hard walled cultivars in an effort to demonstrate this effect, but unfortunately the block was uprooted due to low cocoa prices before it gave conclusive results.
Behavioral control (Pheromone trapping)
In 1981 Day showed that female CPB moths attract males by releasing pheromone. This pheromone was identified and synthesized. A trapping method was designed that trapped many more male moths using synthetic pheromones than could be caught in traps baited with female CPB moths. In 1987 a race of CPB was found in West Malaysia that did not respond to the pheromone used in Sabah. Analysis showed that the mixture of pheromone molecules in the new race was different from the original formula. The new mixture was shown to catch CPB moths in West Malaysia and in Sabah as well, casting doubt on the future of mass trapping and raised questions about the origin and interactions of the two races. More importantly there was a fear that further races could develop or appear which would require frequent change adding to costs and limiting efficacy. As a result the use of pheromones to control CPB has not been explored further.
Mechanical control (Sleeving)
The idea of sleeving pods with bags of plastic or other materials to prevent egg laying originated in Indonesia. If thin plastic bags are placed on very young pods (<7-cm length), with open bottoms for ventilation, and left throughout the pod maturation period, virtually complete protection can be obtained. Cost is the main obstacle to the use of this control method, since the labor for installing the bags is expensive. It is unpractical to put bags on pods that cannot be reached from the ground. Sleeving is unlikely to be a feasible option for cocoa grower.
In October 1995 in response to the major threat CPB was to world cocoa production, ACRI, ASKINDO, and ADP-USAID organized a Workshop on the Management of the Cocoa pod Borer in Indonesia. All previous research was reviewed and management control approaches were discussed. The workshop attendees recommended a demonstration project of cultural practices (pruning), complete-frequent-regular harvesting (CFRH), targeted spraying and good agronomic practices. As a result of the Workshop the Indonesian Cocoa Association (ASKINDO), ACRI and the Biscuit, Cake, Chocolate and confectionery Alliance (BCCCA), joined together to establish the Cocoa Pod Borer Management Project (CPBMP), to verify via a demonstration project the effectiveness of the Workshop recommendation. Two demonstration sites were established, one at Sarjo, Manuju, and one at Wotu, both in South Sulawesi. Both sites were highly infested by CPB. Each site consists of 5 one-hectare treatment plots and two control plots. The treatments were;
P1 pruning + CFRH
P2 pruning + CFRH + Spraying
P3 pruning + CFRH + fertilizer + side grafting
P4 pruning + CFRH + spraying + fertilizer
P5 pruning + CFRH + fertilizer
P6 control area # 1 no control activities for CPB
P7 control area # 2 no control activities for CPB
Table: Combined results from both Demplots (six months data) per 100 trees
|Plots||Pods||Kg dry cocoa harvested|
|All Plots (P1-P5)||4344||165|
|P1, P3, P5 no spray||4356||161|
|P3, P5 + fertilizer||4438||173|
|P2, P4 + spray||4476||172|
|Control (avg. 6-7)||1290||37|
In only six months the results of a field demonstration, in actual small farmers fields, showed a more than 4-fold increase on harvested pods and sellable cocoa beans. The demonstration is continuing for an additional six months to obtain a full years data.
Recommendations for CPB Control
As a result of a short demonstration of a recommended cultural practice it became very obvious that the cocoa tree as it is grown in Sulawesi will respond to cultural CPB control management practices. The increased yield was obtained by practices that any small farmer can do. He does not need anything but his machete and the understanding that what he is doing will increase his income.
Actions: Top prune to approximately 3 meters (practical harvesting height) soon after a high crop period; maintenance pruning every 3 months to keep canopy light and open. Remove chupon growth monthly.
Rationale: an open canopy stimulates yield, is less attractive to the most common cocoa pest and disease problems and makes other controls more effective.
Purpose: To create a canopy architecture that is relatively unattractive to cocoa pod borer moths (and rats and black pod disease); to improve the effectiveness of cultural and chemical control action; to improve yields by improving crop physiological efficiency.
I have now just presented to you the case history of a specific problem within the world cocoa production community. This case history could have been on black pod, witches broom, monillia, or others. It is but one of many examples that prevent the long term, sustainable production of cocoa in a economic format that is compatible with the consumers of chocolate and cocoa products in the world.
During the past thirty years the production community has tested cocoa production in large-scale models such as other commodity crops, rubber, oil palm, coconut, etc, and it has failed. There are many reasons for the failure and I am sure that in the future cocoa will again be tested on a larger size production model. However for the foreseeable future (world production for the next 25-30 years) small farmers will produce the world's cocoa production. My definition of a small farmer is 2 ha of cocoa trees or smaller (average one ha). This generally means that farmers will have less than 2500 cocoa trees. Fifty percent of these farmers will have one ha or less (1000 trees). If 90% of the world's cocoa production comes from small farmers (1998 estimated world production 2.750 million metric tons) then 2.475 million metric tons will be produced by small farmers. Assuming an average yield of 500 kg/ha or less means we have approximately 5 million small cocoa farmers from over 40 countries. If we develop a model for sustainable cocoa production systems how do we deliver that technology (combination of new tree genetics, cultural practices, biological control) to the world's cocoa farmers?
We have not solved the long term pest and disease problems associated with cocoa production worldwide. I do not know of any major pest or disease that has been solved or reduced to a minor problem in the past 50 years. We run away from the problems by looking for new areas to grow cocoa. We spend a few months or years working on a specific problem (CPB, Witches Broom, Capsids, etc.) when prices are high and supplies are tight, then when conditions change we seem to forget and let the cocoa farmer fend for himself. If we can't solve the problems then we should provide the cocoa farmer with the tools (cultural Practices) necessary to sustain a livelihood (cocoa production) using the best environmentally friendly management practices (advise) available. Small farmers need our help the most when prices are low, when his income source is threatened, and cocoa trees have a lot of competition for his time and energy. Cocoa yields today are not any higher in most of the world than they were fifty years ago and in many cases lower. We have a trend of cocoa production moving to new areas (the latest is Indonesia) and the cocoa grows well with good yields for a few years (10-20) and the farmers are rewarded with a good quality of life. Then the honeymoon is over, pest and disease pressures build, no answers are available, yields decline and the world looks for a new cocoa production frontier.
I know I have posed more questions than answers, however, we must understand the problem before we can develop answers.
What We Know!
- Cocoa is a small farmer crop.
- Cocoa requires a lot of attention compared to other commodity tree crops (rubber, oil palm)
- Cocoa will respond to individual attention.
- How to propagate vegetatively
- A small farmer in most countries with 1000 trees that can produce 1000kg of cocoa a year can provide for his family.
- A small farmer in most countries with 2500 trees that can produce 2500kg of cocoa a year can provide for his family and improve his quality of life.
What We Think We Know!
- How to control pests and diseases.
- How to educate and train small farmers
What We Don't Know (But What Might Work):
- How and when to replant cocoa!
- Use cultural practices to control pests and diseases.
- Develop a strategy of short term, medium term and long term research and development objectives specifically to provide production support for small farmers. We need to review and evaluate cultural practices (Machete technology) as a short term strategy to control pests and diseases while at the same time using our new technology tools (Biotechnology) to develop long term solutions.
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Beevor, P.S., Cork, A., Hall, D.R., Nesbitt, B.F., Day, R.K. and Mumford, J.D. (1986) components of female sex pheromone of cocoa pod borer moth, Conopomorpha cramerella. Journal of Chemical Ecology, 12:1-23
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