| dc.description.abstract |
Anthranose caused by the fungus Colletotrichum gloeosporiodes (Penz) Penz and Sacc. is the
major post harvest disease of mango (Mangifera indica) in Sri Lanka and this fungus is extremely
variable in its morphology. A study was done to evaluate and identify the variations in
Colletotrichum gloeosporioides among the cultivated Mangoes in Sri Lanka, in which isolates
were obtained from infected fruits of mango vaieties viz: Villard , Selai.Petti, Neelam, Wal,
Vellaikolumban, Karthakilumban, Kohu, Papal and Gira. After ten days on PDA at 28°C under
continuous while light, morphological characters (colour, appearance and growth rate) of the
culture were closely examined and were grouped as fast growing colonies (FGC) and slow
growing colonies (SGC) based on the growth rate of colonies, determined by their diameters. The
diameter of FGC ranged from 41.00 to 52.83 mm meanwhile that of SGC was 34.75 to 38.00mm
at 14 days of incubation. The lengths of at least 30 conidia per isolate were measured
microscopically and were subjected to ANOVA in SAS statistical package. Pathogenecity of each
isolate was tested with the commercially available variety petti amba. Two different groups were
identified with respect to colony characteristics. Isolates from Karthakolumban, Vellaikolumban
and Kohu showed the slow growth rate meanwhile the rest of the isolates were fast growing
colonies. There was significant variation among the mean lengths of spore of each isolates,
ranged from 6.583 to 12.250 µm. The results indicated than the growth rate of colonies and the
spore lengths are not related. The results of the pathogenecity tests for each isolate showed that
there were variations in the lesion sizes developed by different isolates of Colletrichum
gloeosporioides; however, cross compatibilities of these isolates over the mango varieties have
been noticed. |
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