This document summarizes breeding efforts in Ghana to develop cocoa varieties tolerant to Cocoa Swollen Shoot Virus Disease (CSSVD), the most economically important cocoa disease in Ghana. Breeding activities at the Cocoa Research Institute of Ghana (CRIG) focus on screening new cocoa genotypes for tolerance using conventional and molecular methods. Some tolerant hybrids have been released to farmers to help manage CSSVD, but tolerance levels decreased over time, so breeding continues to identify new sources of resistance. Current achievements include cocoa seedlings supplied to farmers with some CSSVD tolerance and identification of new candidate varieties for resistance.

1. BREEDING FOR TOLERANT VARIETIES FOR
COCOA SWOLLEN SHOOT VIRUS DISEASE
(CSSVD) IN GHANA
George Ameyaw and Abu Dadzie
CRIG, New Tafo, Akim, E/R

2. PRESENTATION OUTLINE
• Cocoa production in Ghana
• Important diseases of the cocoa plant
• Breeding for CSSVD tolerant/resistant
varieties
• Methods for breeding and selection for
tolerance
• Supply of CSSVD tolerant varieties to
farmers

3. Cocoa growing regions in the world

4. Cocoa production in Ghana
• Ghana is the 2nd largest producer of cocoa beans after
Ivory Coast
• Western region of Ghana produces 55% of total cocoa
beans from Ghana
• Cocoa is a major foreign exchange earner for the country

6. RESEARCH ON COCOA
• CRIG is structured into scientific divisions/units and
supporting divisions/units to facilitate research on
various aspects of cocoa and other mandate crops
Scientific Division Scientific Unit Supporting
Division/Unit
Agronomy
Soil Science
Plant Breeding
Plant Pathology
Entomology
Physiology/Biochemis
try
Social Science
and Statistical
Unit
New Products
Development
Unit
Plantation
Management
Administration
General Services
Accounts
Audit
Scientific
Information
6

7. Important cocoa diseases in Ghana
• Black pod disease and Cocoa Swollen Shoot Virus
Disease (CSSVD) are the most economically important
diseases of cocoa in Ghana.

8. INTEGRATEDCONTROL
CHEMICAL
BIOLOGICAL
RESISTANT
VARIETIES
CULTURAL
Black pod
Phytophthoramegakarya
Black pod
Phytophthorapalmivora Warty pod Charcoal pod rot
Mealy pod
Stem canker
Root rot Pink disease Cushion gall
MistletoeWhite thread blight disease
’Advanced stage’ Phytophthoraleaf blight
Seedling leaf blight
White thread blight
disease ’Early stage’
Pictures courtesy A.Y. Akrofi, Plant Pathology Div., CRIG, Akim Tafo
FUNGAL DISEASES OF COCOA
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9. Sympt oms of
cocoa swol l en
shoot disea se
BARRIER
CROPPING
RESISTANT
VARIETIES
CUTTING
OUT
REMOVALOF
ALTERNATIVE
HOST PLANTS
INTEGRATEDCONTROL
VEINCLEARINGIN
MATUREDLEAVES
REDVEIN-BANDINGIN YOUNG
LEAVES
SWELLINGSON CHUPONS
ROUNDEDPOD
ROOT SWELLING
DIE-BACKAND DEATH OF
CSSV INFECTEDTREES
MEALY BUGS-VECTORSOF CSSV
V
I
R
U
L
O
G
Y
S
E
C
T
I
O
N
9

10. CSSVD in Ghana
• CSSVD was reported in Ghana in 1936
•The disease is spread by mealybugs (Homoptera) insects
as a vector
• More than 250 million cocoa trees have died as a result of
CSSV infection in Ghana (Approximately annual loss of
about 50 million metric tonnes of raw cocoa beans)

12. CSSVD control in Ghana
• CSSVD is mainly managed through “cutting out” of infected
trees from affected areas (The oldest and most used
strategy)
• Other interventions include:
Use of resistant/tolerant varieties
Barrier cropping
Eradication of wild host
Mealybug control (Biological means of managing the
vectors)
Mild strain cross protection

13. Use of resistant varieties to control CSSVD
Local materials (Amelonado) were susceptible to the CSSVD
Hence, breeding for CSSVD resistance became the focus of
research activities of the British Research Team (BRT) between
1969 and 1978
Some CSSVD tolerant hybrids (crosses between two parents)
were released to farmers in 1987 to control CSSVD

14. Use of resistant varieties
Nonetheless, tolerance levels of the released materials
decreased over time. Hence the search for new cocoa
genotypes with high level of tolerance/resistance to the
disease.
screening of new cocoa genotypes using conventional
breeding methods and molecular methods.
It is considered that resistant/tolerant cocoa varieties hold
the key to CSSVD management

15. Screening of new cocoa genotypes
Methods for screening of new genotypes includes:
Natural selection of cocoa trees which are not showing
symptoms in endemic areas.
Using them as parents to generate best performing
offspring's (tolerant to the disease).
The hybrids are evaluated both in the Lab and on the field
Best performing genotypes are selected and multiplied for
farmers through the Seed Production Unit (SPU) of Ghana
Cocoa Board.

16. Current Breeding activities
Effect of CSSVD mild strains on growth and yield of cocoa
• Determination and selection of cocoa progenies which show tolerance and
also perform better when inoculated with mild strains of the virus
Assessment of the protective capability of mild CSSVD strain against
severe strains
• Determining the natural spread of CSSVD in different cocoa progenies.
Evaluation of some international clones for CSSVD resistance. (materials
from cocoa growing countries in the world)

17. Current Achievement
Through these breeding techniques:
Current cocoa seedling supply to farmers from SPU have
some level of tolerance to the CSSVD disease
New candidates for CSSVD resistance have been
identified
These types of cocoa yield more and can live longer in the
mist of occurrence of the disease

19. Breeding on other aspects of cocoa
Breeding on other aspects of cocoa e.g.
Drought tolerance
Pest resistance
Disease resistance
High yield
Best flavour
Etc Etc
are among some of the on going activities at CRIG for more
improved cocoa varieties for farmers

20. THANK YOU 20