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ARS Home » Southeast Area » Miami, Florida » Subtropical Horticulture Research » Research » Publications at this Location » Publication #362140

Research Project: Development and Application of Genomic-assisted Breeding Strategies to Produce Disease-resistant Cacao Genetic Resources

Location: Subtropical Horticulture Research

Title: Phytophthora canker affecting CCN51 clones on high productivity cacao farms in Ecuador

item Puig, Alina
item Gutierrez, Osman

Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 7/4/2019
Publication Date: 8/4/2019
Citation: Puig, A.S., Marelli, J., Suarez-Capello, C., Gutierrez, O.A. 2019. Phytophthora canker affecting CCN51 clones on high productivity cacao farms in Ecuador. American Phytopathological Society Annual Meeting. Plant Health, Cleveland, August 3-7, 2019.

Interpretive Summary:

Technical Abstract: Phytophthora spp. cause the greatest losses in cacao (est. 800K MT/year), causing disease on both pods and stems. Management practices and site characteristics influence disease development by promoting or preventing pathogen growth and survival. In Ecuador, high levels of canker disease were reported on CCN51, a widely planted clone. However, the epidemiology of canker infection in the field is poorly understood. The objective of this study was to identify variables affecting canker development and establish baseline for incidence on commercial farms. Data on productivity and incidence of Phytophthora canker and black pod disease were collected every 2-3 weeks, on 25 randomly selected trees on each of the 12 plots representing different agronomical conditions. The pathogen was isolated from stem and fruit lesions, and identified as Phytophthora palmivora, based on ITS and COX1 sequences. Canker incidence ranged from 0 to 28% of trees observed with infections more abundant during dry season (Jun-Aug). Although cankers may not cause mortality, they can reach up to 2 m in vertical length. No canker was observed on trees of the Nacional background genotype, supporting the hypothesis that CCN51 was relatively more susceptible. Pod infection was greatest from Jan-March, with 1.2-6.9% of pods per tree infected during this time. No relationship was found between pod infection and canker. In addition, planting density did not appear to affect disease development, with the most densely planted lot (1800 plants/hectare) having the lowest incidences of pod rot and canker. In addition to providing valuable baseline disease data for CCN51 in South America, this study identifies factors that influence disease development.