Testing local cocoa selections in three provinces in Sulawesi: (i) Productivity and resistance to cocoa pod borer and Phytophthora pod rot (black pod)

Testing local cocoa selections in Sulawesi: (ii) resistance to stem canker and pod rot (black pod) caused by Phytophthora palmivora

“…The trials were established in 2008 using clonal grafted seedlings (12 clones) in an 8-tree plot design with 4 replicate blocks, at a planting distance of 3 m  3 m. Included in the trial were clones developed from breeding programs in Malaysia and the Indonesian Coffee and Cocoa Research Institute and high yielding local clones selected by Mars Inc., with four clones common to the two trials. The local selections included in the trials were described previously by McMahon et al (2015). The trials were managed with normal farm practice as recommended by extension offices, such as pruning, manual weeding, fertilizing and harvesting, except that no chemical pesticide was applied during the assessments.…”

“…Ppr infection and cocoa pod borer infestation in the field was evaluated from 2010 to 2012 on individual trees of both trials (in Pinrang and Polman) during the harvesting periods (every fortnight) as described previously (McMahon et al, 2009(McMahon et al, , 2015. Healthy pods (with no visible infection or infestation) were counted.…”

“…In Sulawesi, differential responses of local genotypes to pests and diseases, largely selected from farms have been reported previously (McMahon et al, 2009(McMahon et al, , 2015. Evaluation of four clones in different parts of Sulawesi indicated average annual incidence of Ppr in ripe pods was 11e14% in the district of Kolaka and 4e12% in Pinrang and Polewali-Mandar (or Polman) districts (McMahon et al, 2015).…”

“…Evaluation of four clones in different parts of Sulawesi indicated average annual incidence of Ppr in ripe pods was 11e14% in the district of Kolaka and 4e12% in Pinrang and Polewali-Mandar (or Polman) districts (McMahon et al, 2015). The higher annual rainfall and number of wet days in Kolaka, compared to the other sites, probably accounts for the higher rates of Ppr occurring at this site.…”

“…Here we report on the field incidence and severity of stem canker in the trials in Pinrang and Polman districts, and the response of stems and pods of the same clones to inoculation with P. palmivora isolated from the field. The main objective of this study was to establish whether resistance to Ppr and/or stem canker could be identified among the clones under test with two sub-objectives of determining (i) whether resistance to Ppr and stem canker occur in the same clones and (ii) whether responses to artificial inoculation of stems and pods correlate with the field observations of canker in this study and the Ppr assessments conducted previously between and 2012(McMahon et al, 2015. The study showed that positive correlations occurred between the responses of the clones to artificial inoculation and incidence of Ppr and canker in the field.…”