first rule for managing most cocoa pests is to grow a healthy crop (e.g.
apply fertiliser to replace soil nutrients). Basic good
agricultural practices (GAP) include:
shade management, removal of mistletoe, etc.;
not let trees grow too tall and maintain a suitable tree height; there
are various techniques for rehabilitating trees, but they usually involve
substantial loss of crop over 2-3 seasons;
pods as regularly as possible and note: there is a difference in emphasis
between sanitary harvesting and regular complete harvesting (recommended for the severest problems such as FPR and CPB);
infected/infested crop residues;
avoiding nearby trees that act as alternative hosts (e.g. kola
trees in Africa that may encourage mirids and P. megakarya; in
Asia CPB also feeds on rambutan).
tree rehabilitation in Ecuador
pod: Phytophthora spp.
picture above was taken in Ghana, where fortunately, beans may sometimes
be extracted from pods showing disease sypmtoms on the outside - unlike Moniliophthora diseased pods
of the cultural methods listed above are essential.
Poor aeration within the crop canopy may encourage the disease, so thinning
the canopy can help. Fungicides will only work well in combination with
appropriate good tree height and canopy management facilitates pod inspections.
soil on cocoa trunks: soil tunnels built by ants on the surface of cocoa
trunks must be removed. This eliminates two sources of disease: spores
carried in infested soil and those carried by the ants themselves.
appropriate fungicides using correct application
compounds and metalaxyl are widely available fungicides that are effective.
health and general good crop management are essential. Soils contain
nutrients for the cocoa trees, but also can harbour the pathogen. Soils
with high organic matter and good drainage help prevent inoculum splashing
and spreading in puddles of water.
hyperparasite Trichoderma asperellum appears to be the most promising
biological control agent found to date.
have been successfully treated by trunk
injection of potassium
Invasive Moniliophthora diseases:
broom M. (Crinipellis) perniciosa
pod rot (FPR) M. roreri
pictureshow that with Moniliophthora diseased pods, outside lesions may
appear less serious than bean loss.
- Maintain canopy height and structure - annual pruning (usually once
in the dry season) helps control brooms
- Recognise early symptoms (and note FPR affects other Theobroma spp.)
practices to ensure yield and improve natural resistance from trees
(shade management, weeding, chupon removal and fertilization).
removal of infected pods during the epidemic season to prevent FPR from
sporulation and reduce inoculum pressure
from peak of flowering then perhaps 3 months (up to 6 applications of
fungicides) for pod protection. Applications of protectant
fungicides, especially copper, are known to reduce disease incidence
and increase yield: chlorthalonil is more toxic. Good
application methods for chemical and biological control agents are
the long term: it is important not to spread infected material from
one region to another. Resistant varieties may become available, but
potentially useful genotypes are very limited.
picture on the left was taken in Ecuador where the two Moniliophthora diseases occur - and must be managed - together.
cocoa pod diseases
are rarely severe enough to warrant control measures other than standard cultural methods (see above).
Cococa Swollen Shoot Virus Disease
diseases and vectors
diseased trees as well as their neighbouring cocoa trees (that might
look healthy, but are expected to be infected with the virus). This
works for small outbreaks. When more than 100 trees in any one area
are diseased, adjacent cocoa trees up to 15 m away with disease symptoms
should be removed.
methods include using resistant cocoa trees when replanting cocoa. Check
with your local cocoa research institute and find out about resistant
establishing new cocoa farms, where possible, plant trees away from
known CSSV areas. Use natural barriers, such as are oil palm, coffee
and citrus to prevent or slow-down the spread of the mealy bugs within
of systemic organophosphate insecticides was tested to control mealy
bugs was hazardous and had little effect; insecticides are not currently recommended.
streak die-back (VSD):
is some scope for host plant resistance - refer to your local breeding
of seedlings is especially crucial.
symptoms are found at an early stage in more mature trees, hard pruning
well beyond the infected parts of a branch and destruction (preferably
burning) of removed plant material may be effective.
are probably not cost effective for wide-scale spraying of mature trees,
and are used mostly for protecting seedlings, using triazole
compounds such as tebuconazole, triadimefon and triadimenol.
diseases (causing tree death)
trees become infected with diseases such as Ceratocystis, and especially
when Xyleborus beetle holes (indicated by arrow: note frass below)
are found, the most effective course of action is to uproot trees and
burn infected plant material. No cocoa varieties have yet been
found that are tolerant
to Roslinia spp.
of this, dispose of infected branches before beetles appear and before
the fungus has a chance to sporulate on the cut ends of branches and stumps.
Wound treatments with tree paints or protectant
fungicide pastes on uninfected trees may also help control the disease.
H. antonii (Java)
African mirids (capsids):
theobroma adult (3rd
a complete canopy: in young plantings, temporary shading is needed, e.g. with bananas and plantains.
chupons regularly: mirids are attracted to the young and soft shoots
that cocoa trees grow throughout the season. Chupons that emerge at
the base of trees should be removed regularly, not just during the peak
mirid season. Do not prune too heavily as this will stress the trees
and cause the growth of new chupons, which increase mirid feeding.
cocoa varieties are affected by mirids, but modern ones less so than
Amelonado (possibly tolerance to infections of Calonectria rigidiuscula and other mirid transmitted fungi that may cause cocoa dieback). Improved
varieties have been offset by changes to the agricultural environment:
a trend towards reduced shade encourages mirids.
are widely used and effective: especially when timed correctly (often early in the season). If possible, only spray those areas in
the farm that are attacked by mirids (spot application). Careful
and well-timed application can help farmers to save money by using
less insecticide, and decrease impact on natural enemies of this pest.
In the past, organochlorine
insecticides (e.g. lindane, endosulfan) and carbamates (propoxur and promecarb) have been chosen with vapour action and persistence
to counteract poor application. Many of these have been, or are in the
process of being, withdrawn.
Modern, less toxic insecticides, such as neonicatinoids,
are now available, but these are expensive and not always available. Pyrethroids can be effective, but they may kill beneficial insects such as pollinators,
so these must only be used as little as possible and only where mirids
Note: some insecticide products are mixtures, e.g.:
profenfos + lambda-cyhalothrin - 'Gammalin Super'
endosulfan + deltamethrin - 'Cracker'
pirimiphos methyl + bifenthrin - 'Talstar', 'Cocostar'
lines of research that especially show potential and may be useful in
- mirid pheromones
For the latter, we are currently searching
pod borer (CPB)
temporarily covered with plastic sheet to prevent CPB hatching (PRIMA,
complete harvesting of pods is almost certainly the most effective cultural
cultural techniques include: rampassan
(enforcing a break in pod production) and removal/burying/enclosing
husks (below left)
chemical control has been most effective with broad spectrum insecticides.
These originally included organochlorines (e.g. gamma-HCH or endosulfan) that have now been - or are in
the process of being - withdrawn for safety and environmental reasons.
Farmers in Sulawesi are left with a choice between oganophosphates (e.g. chlorpyrifos) and pyrethroids (e.g. cypermethrin, deltamethrin, lambda-cyhalothrin) and fipronil
(similar mode of action to organochlorines).
situation is not satisfactory, and collaborative
research is currently underway to investigate alternative, safer,
effective, but more environmentally sound products such as insect
growth regulators, but these appear to be less effective and more
expensive than neurotoxic insecticides.
important lines of research and development:
- pheromones: for monitoring
(possibly mass trapping / mating disruption);
- sleeving (preferably with biodegradable plastics - below).
at biological control have proved disappointing to date.
- Maintain a healthy and balanced ecosystem to preserve natural enemies
that kill lepidopteran stem borer caterpillars. Use pesticides rationally
to keep insect pests in check and to preserve natural enemies of stem
a barrier crop that is not attractive to stem borers, such as: Leucaena
glauca, cocoyam, sweet potato or Pueraria species. The barrier
must be at least 15 m wide and established early for new plantings.
has been suggested that attacks have been caused by heavy pesticide
use on trees, which kills off the natural enemies (insecticide resurgence).
However, from the 1990s onwards, stem borer has become more noticeable,
even on farms where no pesticides are used.
Papua New Guinea, stemborers and associated Phytophthora cankers
can kill up to 2% of cocoa trees annually, so they have been controlled
by applying oganophosphates with fumigant action (e.g. DDVP) mixed with a fungicide such
and other vertebrate pests
traps and nooses are popular, but of little value for lowering populations:
a combination of good practices is most likely to be successful. These
must be implemented over large areas as rodents reproduce and
spread quickly. Whole communities should work together, if possible.
- Good farm management (weeding, light shade management, timely pruning,
etc.) is important.
owls are probably the most proven biological controls for rodents. When
barn owl nest boxes were established in cocoa plantations in Malaysia,
rat damage was significantly reduced. Recently a control product has
been brought out based on the pathogen Sarcocystis
rodents attack more than 4 out of 100 cocoa pods, farmers may want to
think about chemical control. Rodents can be baited and killed with
poisoned wax blocks (containing the anti-coagulants: brodifacoum, bromadiolone
or warfarin), tied high up on trees to help avoid poisoning of children
and farm animals. Baiting with anti-coagulant rodenticides is most likely to work when farmers co-operate and treat as large an
area as possible at the same time - best in the low season when rodents
are most hungry. Another problem is that rats adapt and learn quickly
not to eat the poison (bait shyness).
At least 6 different species of Mistletoe have been found on West African cocoa. One species Tapinanthus bangwensis accounts for about 70% of infestations in Ghana and is recognised by its red flowers and berries: it flowers twice a year and can live for up to 18 years. Regular removal of mistletoe is essential for good crop management and in healthy cocoa crops, misletoes are not able to become established; large populations can be considered a sign of farm neglect. Mistletoe may also provide a suitable habitat for ants (Crematogaster sp.) which cultivate the mealybugs vectors of CSSVD.