Resistance of four cacao varieties to Phytophthora palmivora
Seedlings of four cacao (Theobroma cacao) varieties (Catongo, Pound 12, UF 221, and UF 613) were tested for resistance to Phytophthora palmivora, by both root and stem inoculations. Catongo, a clone resistant in Brazil to pod rot caused by P. palmivora, had significant resistance to stem and root inoculations in three tests. The mean length of stem cankers on Catongo after 6 weeks was 3.1 cm, compared with 11.9-cm cankers on UF 221, a clone highly susceptible to pod rot in the field. Root invasion by P. palmivora was extensive on all clones when seedling roots were subjected to zoospores in aerated nutrient solution. Isolates of P. palmivora from Nigeria, Brazil, Costa Rica, and Mexico did not vary significantly in their pathogenicity to seedlings of UF 613. P. cinnamomi caused small, limited lesions on cacao stems; the fungus was recovered from discolored bark and wood 6-8 weeks after inoculation.
| Main Authors: | , |
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| Format: | biblioteca |
| Published: |
May
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| Subjects: | THEOBROMA CACAO, PLANTULAS, VARIEDADES, PHYTOPHTHORA PALMIVORA, ENFERMEDADES FUNGOSAS, RESISTENCIA A LA ENFERMEDAD, CULTIVAR CATONGO, CLONES POUND, CLONES UF, INOCULACION, AISLAMIENTOS, BRASIL, NIGERIA, COSTA RICA, MEXICO, |
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