Variation In Cultural And Morphological Characters Within Cocoa Isolates Of Colletotrichum Gloeosporioides

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dc.contributor.authorChandra Mohanan, R.
dc.contributor.authorKaveriappa, K.M.
dc.contributor.authorNambiar, K.K.N.
dc.date.accessioned2014-08-19T08:48:07Z
dc.date.available2014-08-19T08:48:07Z
dc.date.issued2007
dc.description.abstractIsolates of Colletotrichum gloeosporioides Penz. causing infection on leaves and pods of cocoa were collected from various cocoa gardens in the southern states of India. The isolates were grouped into three groups based on the symptoms produced on cocoa leaves, viz., leaf blight, shot hole and irregular spot. Cultural and morphological characters of 299 isolates causing leaf blight (210 isolates), shot hole (77 isolates), and irregular spot (12 isolates) symptoms were studied. When the isolates were grown on potato dextrose agar medium for 10 days, they showed great variability in colour and consistency of the mycelium, growth rate, degree of sporulation and size of conidia indicating that there is considerable amount of genetic heterogeneity. The isolates from each of the three symptom groups were classified into white, dark and light types based on the colour of the colony. The light type isolates showed the highest degree of sporulation. Rate of growth was the highest in white and dark types, whereas sporulation was the lowest in these groups. Out of a total of 299 isolates collected from various symptom groups, 249 isolates were of light type indicating the predominance of this group among the population of C. gloeosporioides. There was significant negative correlation between rate of growth and degree of sporulation among the isolates. The white, dark and light types could be further classified into groups and subgroups based on the marked variation in the rate of growth, sporulation, presence of acervuli and conidia size. Of the 299 isolates, 28 produced acervuli on 10-day-old cultures of which 26 belonged to light type. There was marked variation in the size of the conidia. Seven isolates of the light type culture group produced perithecia with asci ascospores in 10 to 20-day-old cultures. Isolates belonging to light type have been reported as more pathogenic than the other two groups. There appeared to be marked interrelationship between colony colour, rate of growth, sporulation and virulence. The higher rate of sporulation coupled with more pathogenic nature of the light types appears to help them to perpetuate and predominate under natural condition.en_US
dc.identifier.citation10th International cocoa research conference 491-497en_US
dc.identifier.urihttp://hdl.handle.net/123456789/4844
dc.language.isoenen_US
dc.titleVariation In Cultural And Morphological Characters Within Cocoa Isolates Of Colletotrichum Gloeosporioidesen_US
dc.typeArticleen_US

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