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Colletotrichum lindemuthianum is a fungus which causes anthracnose, or black spot disease, of the common bean plant (Phaseolus vulgaris).It is considered a hemibiotrophic pathogen because it spends part of its infection cycle as a biotroph, living off of the host but not harming it, and the other part as a necrotroph, killing and obtaining nutrients from the host tissues.
A view of an infected pepper . Colletotrichum capsici has a broad host range but prefers peppers, yams and eggplants. On chili peppers, Capsicum annuum L., C. capsici infect the stem, fruit, and leaves of the plant, causing anthracnose, die-back and ripe fruit rot.
The black spots are circular with a perforated edge, and reach a diameter of 14 mm (1 ⁄ 2 inch). Badly affected plants, however, will not show the circular patterning, as they combine to cause a large, black mass. The common treatment of the disease is to remove the affected leaves and spray with antifungal solutions.
Small black dots may form beneath the epidermis of the lower stem and in the taproot, giving the stems and roots a charcoal-sprinkled appearance. [8] When the epidermis is removed, small and black microsclerotia (a sign of the disease) may be so numerous that they give a greyish-black tint to the plant tissue. [ 8 ]
You can find the mycelium in the roots of the plant between the cells of the cortex (near the cambium). The parenchyma inside of the leaves becomes infected. When in a young plant, hyphae may be found in any of the tissues. In the affected organs of the plant, the mycelium develops haustoria, which appear as side branching from the mycelium. [6]
A sign of black dot disease is black microsclerotia that are produced by the pathogen, and can be found on the roots, the tuber, the stems, and the leaves. [3] This can be used to diagnose black dot. Symptoms of black dot disease include silvery lesions on the surface of the tuber, brown or black lesions on the leaves, leaf wilting, and ...
White mold affects a wide range of hosts and causes sclerotinia stem rot. It is known to infect 408 plant species. As a nonspecific plant pathogen, [2] diverse host range and ability to infect plants at any stage of growth makes white mold a serious disease. The fungus can survive on infected tissues, in the soil, and on living plants.
The fungus grows as mycelium which penetrates successive leaf sheaths throughout the growing season. High humidity, cool, and damp weather at the soil surface favours disease development. [1] [2] Whilst dry and hot weather causes the leaf sheaths of the plant to dry and fall off, taking the inoculum with it, thus lessening disease.