Colletotrichum Disease of Cocoa (Theobroma Cacao L.) and its Control
Isolation of disease pathogen from infected cocoa leaves and pods associated with leaf spot and pod rot disease yielded Colletotrichum gloeosporioides. No distinct differences in cultural and morphological characteristics were noted from the various isolates. Further investigation by polyacryla...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English English |
| Published: |
1991
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/10302/1/FP_1991_11_A.pdf |
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| Summary: | Isolation of disease pathogen from infected cocoa leaves
and pods associated with leaf spot and pod rot disease yielded
Colletotrichum gloeosporioides.
No distinct differences in cultural and morphological
characteristics were noted from the various isolates. Further
investigation by polyacrylamide vertical gel electrophoresis
indicated that protein, esterase and peroxidase patterns were
unable to differentiate strain
gloeosporioides.
variation within C.
The fungus was found to grow and sporulate well at 30°C.
Cocoa Leaf Extract Agar (CLEA) was the best medium for mycelial
growth while Potato Dextrose Agar (PDA) appeared to favour sporulation. Better mycelial growth was also achieved on
substrates of neutral condition while extreme alkaline
condition induces sporulation. Both cocoa leaves and injured pods were liable to
infection by C. gloeosporioides. Three-week old cocoa seedlings
and cherelles were noted as the most susceptible stage.
The development of Colletotrichum leaf spot disease
invariably involved three phases of activity viz., prepenetration
phase which involved spore germination and
formation of appressoria, penetration phase involving
intercellular and intracellular hyphal penetration and postpenetration
phase resulting in disintegration of cells and the
formation of acervuli. |
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