The mechanism of initiation of Phytophthora pod rot epiphytotics
The mechanism of Phytophthora pod rot disease outbreak was studied in a cocoa farm in Ibadan during two successive seasons. Splash-borne particles from the soil were found to contain primary inoculum which induced infection on cocoa pod materials. Insects which had crawled on infested soils in the field also caused infections when placed on cocoa pods. Spore trapping did not detect the presence of Phytophthora spores in the air, and it is probable that the role of the wind in initiating the epiphytotics is very limited. No primary infection resulted from the peduncular end of pods on cushions which were infected by P. palmivora in the previous season. The thick leaf-litter which accumulates on the ground during the dry season formed a mechanical barrier between cocoa pods and the inoculum in the soil, and greatly repressed the onset of the disease. The habit among some cocoa farmers of clearing the leaf-litter in an attempt to control pod rot of cocoa was found to enhance the onset of the disease. The hypothesis that the incidence of the disease is most severe near ground at the beginning of the rainy season was confirmed. It seems possible that a better control of the disease may be achieved by suitable soil treatment and the use of insecticides
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| Format: | biblioteca |
| Published: |
Tafo (Ghana)
1971
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| Subjects: | THEOBROMA CACAO, PHYTOPHTHORA PALMIVORA, PODREDUMBRES, ENFERMEDADES FUNGOSAS, INFECCIONES, EPIDEMIOLOGIA, MECANISMO DE PENETRACION, NIGERIA, |
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| Summary: | The mechanism of Phytophthora pod rot disease outbreak was studied in a cocoa farm in Ibadan during two successive seasons. Splash-borne particles from the soil were found to contain primary inoculum which induced infection on cocoa pod materials. Insects which had crawled on infested soils in the field also caused infections when placed on cocoa pods. Spore trapping did not detect the presence of Phytophthora spores in the air, and it is probable that the role of the wind in initiating the epiphytotics is very limited. No primary infection resulted from the peduncular end of pods on cushions which were infected by P. palmivora in the previous season. The thick leaf-litter which accumulates on the ground during the dry season formed a mechanical barrier between cocoa pods and the inoculum in the soil, and greatly repressed the onset of the disease. The habit among some cocoa farmers of clearing the leaf-litter in an attempt to control pod rot of cocoa was found to enhance the onset of the disease. The hypothesis that the incidence of the disease is most severe near ground at the beginning of the rainy season was confirmed. It seems possible that a better control of the disease may be achieved by suitable soil treatment and the use of insecticides |
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