Abstract
The saprophytic survival of Phytophthora palmivora in infected cocoa residues over the dry season provides primary inoculum for the development of rainy season epidemics of black pod and stem canker diseases of cocoa. In field trials conducted in Papua New Guinea, we examined pathogen survival in various types of colonised cocoa tissues under two different ground covers. Pathogen survival was longest in lignified host organs such as pod cases and twigs, and lowest in infected leaf tissue. Survival in each tissue was shorter under leaf litter mulch than under grass cover. The viability of mycelium discs exposed to soil collected under leaf litter declined more rapidly than in soil collected under grass cover. These results suggest that leaf litter mulches reduce the survival of P. palmivora by accelerating substrate decomposition and by stimulating the activity of antagonistic and hyperparasitic microbes. When used in an integrated disease management program, leaf litter mulches may reduce disease by lowering pathogen populations, particularly at the start of the rainy season.
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Konam, J.K., Guest, D.I. Leaf litter mulch reduces the survival of Phytophthora palmivora under cocoa trees in Papua New Guinea. Australasian Plant Pathology 31, 381–383 (2002). https://doi.org/10.1071/AP02043
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DOI: https://doi.org/10.1071/AP02043