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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.
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.
This disease affects strawberry plant foliage causing purple spots 1 ⁄ 8 to 1 ⁄ 4 in (3.2 to 6.4 mm) in diameter across on the upper side of the leaves. [3] At first, the whole spot is purple but as the disease matures the center of the leaf spots on older leaves become tan or gray, then almost white.
As the disease progresses, the mycelium often becomes dotted with minute black points (cleistothecia), which are the sexual fruiting bodies of the fungus. [3] The fungus does not kill the host plant as it requires the hosts' water and nutrients to grow. It settles on foliage and gradually slows the host growth process.
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 ]
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.
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 black walnut is one of the earliest studied examples of allelopathy and produces juglone, which inhibits growth and water uptake in neighboring plants. [31] In studies of juglone in black walnuts and their target species, the presence of mycorrhizal networks caused target plants to exhibit reduced growth by increasing the transfer of the ...