INTRODUCTION
Black pod disease is a fungal disease of cocoa trees. It is mostly found in tropical areas where cocoa trees grow, and its spores are spread via the heavy rainfalls that can occur in tropical climates. Annually, the pathogen can cause a yield loss of up to 1/3, and up to 10% of total trees can be lost completely.
The pathogen can be found anywhere on the cocoa trees but is most notable for the black mummified appearance it gives to the fruit of the cocoa tree. Causal vectors are ants, rodents, beetles, snails, and etc. Black pod disease only take place in cocoa but Phytophthora species cause disease in tropical plants like breadfruit coconut and papaya
CAUSES OF BLACK POD DISEASE
Black pod disease is caused by several species within the genus Phytophthora, which are fungus-like organisms but are actually oomycetes. The two most important pathogens responsible globally are:
Phytophthora palmivora: Widely distributed in tropical cocoa-growing regions.
Phytophthora megakarya: Found mainly in West and Central Africa, including Ghana, causing more aggressive and damaging infections.
Issues that causes black pod disease in Theobroma cacao
1. High humidity and poor airflow
2. Water logged soil
3. Wounded stem (by excessive pruning )
4. Lack of pruning and weed control.
SYMPTOMS OF BLACK POD DISEASE
The symptoms of black pod disease are necrotic lesions on the cocoa pod that is brown or black in color, which eventually enlarge to cover the whole pod. White mycelia growth on lesions that appears several days after infection is a sign of the causal pathogen of black pod disease, which is Phytophthora spp.
KEY MANAGEMENT STRATEGIES
Remove and destroy infected pod
Improve air circulation and drainage
Use fungicides or biological control method
Practice good agriculture practices
Recommended spray regime
REFERENCES
i. A.Y. Akrofi et al.Management of Phytophthora pod rot disease on cocoa farms in GhanaCrop Prot.(2003)
ii. C.M. Brasier et al.Taxonomy of ‘Phytophthora palmivora’ on cocoa Trans. Br. Mycol. Soc.(1979)
iii. P. Deberdt et al. Impact of environmental factors, chemical fungicide and biological control on cacao pod production dynamics and black pod disease (Phytophthora megakarya) in Cameroon Biol. Control (2008)
iv. S. Nyasse et al. Diversity of Phytophthora megakarya in Central and West Africa revealed by isozyme and RAPD markersMycol. Res.(1999)
I.Y. Opoku et al. Shade trees are alternative hosts of the cocoa pathogen Phytophthora megakarya