POPULATION DYNAMICS OF COLLETOTRICHUM GLOEOSPORIOIDES ON DIFFERENT PARTS OF AN AVOCADO (PERSEA AMERICANA) TREE
Journal of the National Science Foundation of Sri Lanka
Abstmct: Colletolrichuh~. gloeosporioides in difyerent parts of a single avocado tree, and its dehl-is under the tree, was enumerated a t monthly inte~lrals, during a period of two years. A positive cor~.elation between quiescent infections-QI on flowers and rainfall (RF), and a negative correlation of QI on twigs and RF were observed. The positive correlation hetween RF and QI on leaves was signiiicant only when RF was pre-lagged hy 3 months, and the level of significance increased
... creased progressively when RF was pre-lagged upto 6 months. Disease symptoms were never ohsellred on the vegetative parts ofthe tree and flowers, but a high numher of QI was observed on twigs and leaves. This is probably how C. gloeosporioides survives hetween fiviting seasons. Tllc different 1.elationships between QI on each part of the tree and RF, demonstrate how this pathogen may have adopted itself to survive on t h e tree. Thcreforc thc results suggest that onw the C. gloeosporioicles pl-opagules find their way t o a tree, t h e pathogen remains there throughout i t s life time causing anthracnose on fruits. There was a significant drop in t h e density of QI of C. glomsl~orioides on larger, mature f i i t s compwed to that of smaller, immatwe fruits. Tluoughout t h i s study, the free-living viable fungal propagule counts of dehl-is under the tree val-ied from 1 0 ' to 103 CW/g wllile those of washings of leaves, twigs and flowers varied fieom 0 to 10" CFUIg.