This document provides a case study on Phytophthora pod rot, a fungal disease of the cocoa tree Theobroma cacao. It discusses the disease cycle and symptoms, including necrotic lesions and rotting of cocoa pods. The disease is caused by the oomycete Phytophthora and has several species that are major pathogens. It is responsible for approximately 70% of global cocoa crop losses. Management strategies discussed include fungicide application, phytosanitation like pruning diseased material, and breeding resistant varieties, but note that an integrated approach is needed to effectively control the disease.

1. FUNGAL PLANT DISEASES
Case Study
Of
PHYTOPHTHORA POD
OF
CHOCOLATE TREE
(Theobroma cacao)
RUFUS J. AKINRINLOLA
Grad Student, Plant Pathology Department,
University of Nebraska Lincoln,
November 23rd, 2015

2. OUTLINE
 What is Theobroma cacao
 Importance of Theobroma cacao
 Fungal diseases of Theobroma cacao
 Black pod disease (Phytophthora pod rot)
 Disease Cycle and Mode of Dissemination
 Signs and Symptoms
 Dsease Managements
 Managements Limitations
 Summary
 References

3. Theobroma cacao
Cocoa Tree
 Cocoa is a tree plant growing upto the height
of 10metres.
 Is an understory plants –grows under larger
tropical forests trees.
Cocoa pod may contains upto 30 to 40 cocoa beans
Cocoa starts fruiting after 4 to 5 years of
Planting.
Cocoa tree is a perennial crop
Image source: http://www.santabarbarachocolate.com/

4. Theobroma cacao
http://www.worldwatch.org/photohttp://www.technoserve.org/

5. Theobroma cacao
History and Origin
The cocoa plant is indigenous to the tropical rain forests of South and Central America
First discovered by Olmecs (1500-400 BC)- first major civilization in Mexico
Named by Swedish natural scientist Carl Linnaeus, as Theobroma cacao
Theobroma is a Latinized Greek word: “theo” means “god”, and “broma” means
“nectar” or “food”.

6. Theobroma cacao
Historical relevance
First consumed by the Olmecs as chocolate drinks
Used as monetary and measurement units
Used in religious rituals as a dedication to Quetzalcoatl, the god of cocoa
Used as offerings at the funeral of noblemen
Cocoa drink was only available for the privileged and the soldiers during
battle

7. Theobroma cacao
Cocoa worldwide growth
--regions and environmental factors
 Cocoa grows best in tropical regions, between approximately 20° north and 20° south of the
equator
 Most cocoa is grown at an altitude of about 1,200 feet above sea level
 The Ideal temperatures are between 65°F to 90°F (18°C and 32°C).
 Annual rainfall range, between 1,000 and 3,000 mm (400 to 1,100 inches) per year.
 Usually requires protection from direct intense sunlight and excessive winds.

8. Theobroma cacao
Source: http://beannco.com/
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Worldwide cocoa production

9. Economic Importance of Theobroma cacao
Social and economic impact
 Employment
 Income source
 Improved quality of life
 Cash crops to many nations
Export earnings from cocoa
 Cocoa bean
 Semi-finished (Cocoa powder, cocoa
butter)
 Finished products (chocolate)
 Global trade of cocoa bean worth $9
billion dollars

10. Diseases and Pests of Theobroma cacao
--Fungal diseases
Black pod or Phytophthora pod rot:- Phytophthora spp
Monilia or Frosty pod rot :- Moniliophthora roreri
 Witches’ broom :- Crinipellis perniciosa
Vascular streak dieback:- Orcobasidium theobromae
--Pests
Cocoa swollen shoot virus
Cocoa stem borer
Cocoa mirid:-Distantiella Theobroma, Sahlbergella singularis, Helopeltis spp, Monalonion spp.
Cocoa mealybugs:- Planococcus spp. Pseudococus spp.
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11. PHYTOPHTHORA POD ROT DISEASE
Also called Black pod disease of cocoa or PPR
Caused by the Omycetes Phytophthora
 P. palmivora:- causes global yield loss, covering Africa, Asia and America
 P. megakarya:-Central and West Africa; most aggressive of the Pod Rot pathogens.
 P. capsici:-Central and South America,
 P. cithrophora:- Central and South America,
 P. tropicalis
 Responsible for the 70% of cocoa pod loss worldwide
 Main causes of worldwide coca yield loss
 Can infect the roots, stems, leaves, flowers and pods of cocoa

12. PHYTOPHTHORA LIFE CYCLE
http://forestphytophthoras.org/

13. DISEASE CYCLE AND SYMPTOMS
Infection process
I. Initial contact
II. Adhesion and encystment
III. Spore germination and
penetration
IV. Colonization and nutrient
acquisition
V. Sporulation
Hardham, A. R. (2001). The cell biology behind Phytophthora pathogenicity.Australasian Plant Pathology, 30(2), 91-98.

14. DISEASE CYCLE AND SYMPTOMS
Disease symptoms
 Necrotic lesion on pods
• Discolored spot
• Brown or black lesion
• Whole pod blackens and shrivels
• Rot; Pod tissue, pulps and beans
• Chirelle (developing fruit) wilt
 Canker on stems
McMahon et al, 2004

15. DISEASE CYCLE AND SYMPTOMS
Disease Cycle
1. Healthy fruit become infected
2. Brown spots appear and develop 5d after
infection
3. Brown spots cover the entire pod at 8
days after infection
4. At 11 days mycelia cover the entire pod
5. Water, ants and insects disperse the
spores
6. Hyphae become survival spores in soil
and mummified pods
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Wilbert phlilips – Mora, Rolando Cerda, cacao diseases in Central America. Tropical Agricultural research and Higher education Center (CATIE), Turrialba, Costa Rica, 2009.

16. MODE OF
DISSEMINATION
Inoculum
Survival material
 Oospores
 Mycelia
 Chlamydospores
Primary inoculum
 Sporangia
 Zoospores
Secondary inoculum
 Hypha
 Cyst
Sources of inoculum
 Infected soil and roots
 Infected flowers and
leaves
 Infected pods and stems
 Mummified pods
 Contaminated
implements
Mode of
dissemination:-
 Ants
 Insects
 Direct contact
 Rain or water splash
 Wind
 Bats
Guest, 2007

17. MODE OF
DISSEMINATION
Conditions that favor Black pod dissemination
 High rainfall
 High humidity
 Poor drainage
 Heavy canopy
 Low hanging branches

18. BLACK POD MANAGEMENT
Resistant varieties :- Through breeding
Chemical control
 Copper based fungicides
 Cuprous oxide
 Metalaxyl
 Potassium phosphonate
Phytosanitation
 Pruning
 Removal of lowered branches
 Regular weeding
 Regular harvesting of ripe and any infected
pods.
 Burying of infected pods and pod husks
 Addition of manure
Biological control
Natural antagonists of
Phytophthora
Bacillus cereus
B. sutilis
Penicillium spp
Botryodiplodia
theobromae
Plant extracts

19. BLACK POD MANAGEMENT LIMITATIONS
Chemical control
Fungicides spraying is laborious
Fungicides are not cost effective
Chemicals are not ecofriendly
Phytosanitation
Laborious
Strategy is not enough to curb the disease loss
Biological control
Biocontrol agents react differently in different environments
Resistant varieties
Breeding cocoa varieties takes years
Integrated management
 Combining all methods has been the only
effective recommended strategy that is
able to reduce cocoa yield loss to a bare
minimum of about 5-10%, depending on
commitment of the cocoa farmer to the
stress involved

20. SUMMARY AND RECOMMENDATION
Black pod disease affects world wide cocoa production and responsible for 70% of global cocoa bean loss
Black pod is caused by various species of Phytophthora (Plant destroyer)
Phytophthora palmivora has worldwide distribution while megakarya the most aggressive specie is found
in Africa and P. capsici and cithrophora is virulent in south America
 Wet weather and high humidity favor the disease incidence
 Various control strategies including fungicides, biocontrol agents and use of resistant varieties are
engaged against the disease.
Each control strategy alone is inadequate to curb the disease incidence and often comes with one
limitation or another.
 Further research is required to discover a more effective and more environment friendly approach to
manage the disease

21. REFRENCES
 Acebo-Guerrero, Y., Hernández-Rodríguez, A., Heydrich-Pérez, M., El Jaziri, M., & Hernández-Lauzardo, A. N. (2012). Management of black pod rot in cacao
(Theobroma cacao L.): a review. Fruits, 67(01), 41-48.
 Cocoa (cacao) | Diseases and Pests, Description, Uses and propagation, https://www.plantvillage.com/en/topics/cocoa-
cacao/infos/diseases_and_pests_description_uses_propagation
 Guest, D. (2007). Black pod: Diverse pathogens with a global impact on cocoa yield. Phytopathology, 97(12), 1650-1653.
 History of cocoa, http://worldagroforestry.org/treesandmarkets/inaforesta/index.htm
 Hardham, A. R. (2001). The cell biology behind Phytophthora pathogenicity.Australasian Plant Pathology, 30(2), 91-98.
 McMahon, P., Purwantara, A., Drenth, A., & Guest, D. I. (2004). Phytophthora on cocoa. Diversity and management of Phytophthora in Southeast Asia, 104-115.
 Pests and diseaeses of cocoa, international cocoa organization, http://www.Icco.Org/about-cocoa/pest-a-diseases.Html
 Tondje, P. R., Roberts, D. P., Bon, M. C., Widmer, T., Samuels, G. J., Ismaiel, A., ... & Hebbar, K. P. (2007). Isolation and identification of mycoparasitic isolates
of Trichoderma asperellum with potential for suppression of black pod disease of cacao in Cameroon. Biological Control, 43(2), 202-212.