Formulation of Dehydrated Media from the Bean Mucilage and Placenta of Mature Unripe Cocoa Pods for Culturing Phytophthorapalmivora

Abstract:

Because of difficulty in obtaining cocoa pods during the off-cocoa growing season to prepare media from scratch, formulation of dehydrated media from the placenta and seed mucilage of green mature, cocoa pods was attempted for use in culturing phytophthora palmivora. Pieces of mucilage and placenta were oven-dried (70 "C, 6 h), milled and the resulting Hakes sieved to obtain a fine powder. Four powder concentrations 0, 1, 2 and 3 per cent in water (w/v) were prepared, and agar and calcium carbonate added at 2 per cent (w/v) and 2.5 per cent (w/w), respectively, to each powder concentration. The media were autoclaved and evaluated in Petri plates for clarity ami for capacity to support growth and sporulation of Phyloplithora palmivora. Powder yield was higher for the placenta than for the mucilage-based media. The source of powder, powder concentration, and their interaction all had significant effects on radial mycelial growth of P. palmivora. At the same powder concentration, media prepared from the placenta supported significantly higher (P < 0.05) radial growth of the test fungus'(5.59 - 7.10 mm/day) than media prepared from the mucilage powder (4.54 -6.18 mm/day). Aerial mycelial growth improved slightly as powder concentration increased but media clarity decreased. Sporulation of P. palmvora was good on all the media. Powder source, powder concentration, and method of media preparation before autoclaving all had significant effects on radial fungal growth. At each concentration and for each type of powder, growth was faster when the medium was boiled before autoclaving. Media incorporating 2 per cent placenta powder, 2.5 per cent calcium carbonate, and 2 per cent agar prepared by trailing and filtering' with cheese cloth before autoclaving had the best result and are recommended for culturing P. palmivora. This dehydrated medium is easy to prepare, has a PH of about 7, and can be stored for a long time without caking.

 

Authors:

Frimpong, M.

Awuah, R. T. (Department of Crop and Soil Sciences, Professor, awuahrt@yahoo.com, 0322060332)


Place of Publication:

This article was published by the Department of Crop Science, Plant Pathology Unit, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.

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