In this article we will discuss about the morphology and vegetative structures of Colletotrichum.
Morphology of Colletotrichum:
Red-Rot of Surgarcane (Saccharum officinarum).
It occurs commonly on the stem and leaves of sugarcane plants in every sugarcane- growing region, and causes the common red-rot disease of surgarcane. Colletotrichum capsici occurs on Capsicum anum.
Symptoms of the Disease on Sugarcane:
1. The fungus mainly attacks the stems and leaves.
2. The stems, at the high level of infection, get rotten and shrink at the nodes, and become dull in colour.
3. The upper leaves become paler and start to droop down.
4. The stem splits and many red-coloured longitudinal lines are formed on it. These lines extend through many internodes (Fig. 108A, B).
5. The reddening is mainly in the vascular bundles and sometimes also in the pith.
6. Many white patches are also present on the stem in cross-wise direction.
7. The midrib of the leaves also becomes dark red (Fig. 108 A,B).
Vegetative Structures of Colletotrichum:
1. Mycelium is septate, branched, hyaline and intercellular or intracellular.
2. Many oil drops are present in each cell of the mycelium.
3. Mycelium is generally present in the cells of the parenchymatous pith.
Acervulus and Conidia:
1. The fungus only reproduces asexually by forming conidia.
2. The conidia develop on conidiophore, and both these structures form the fruiting body of the fungus called acervulus (Fig. 109).
3. Acervuli are saucer-shaped, flat and black velvety structures.
4. In each acervulus, alongwith condidia and conidiophores, are present many long, branched and septate bristles called setae.
5. Conidiophores are aseptate and cut many unicellular, falcate, hyaline conidia, which, on germination, form the new mycelium.