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Powdery mildew of wheat is relatively easy to diagnose [8] due to the characteristic little white spots of cotton-like mycelia. [9] These can appear on the upper and lower epidermis of the leaves. As the disease progresses they become a light tan color. [9] B. g. f. sp. tritici is an obligate parasite which means it only grows on living tissue.
This mycelial layer may quickly spread to cover all of the leaves. The lower leaves are the most affected, but the mildew can appear on any above-ground part of the plant. As the disease progresses, the spots get larger and denser as large numbers of asexual spores are formed, and the mildew may spread up and down the length of the plant.
White rust is a disease in plants caused by the oomycete Albugo candida or one of its close relatives. Plants susceptible to this disease generally include members of the Brassica family. [ 1 ] White rust has been known to cause agricultural losses in fields cultivating members of this family including broccoli , cauliflower , and Indian ...
Cucumber leaves afflicted with various stages of Cucumber mosaic virus. A mosaic virus is any virus that causes infected plant foliage to have a mottled appearance. Such viruses come from a variety of unrelated lineages and consequently there is no taxon that unites all mosaic viruses.
In their review of the possibilities, they noted the lack of interest and information thus far, and listed what was known of pests-of-pests – whether pathogens or not. They proposed that this should be relatively straightforward to apply in the same way as other biocontrols. [ 69 ]
Hot and dry conditions in the summer cause the fungus to become inactivated and the leaf spots to turn white and crusted. [11] During the summer, the diseased leaves fall leaving only the healthy ones on the partially defoliated trees. This provides a natural control for the disease. [5] The disease also mainly infects young leaves in the ...
The Puccinia species causing wheat leaf rust has been called by at least six different names since 1882, when G. Winter (1882) described the Puccinia rubigo-vera. [5] During this time, wheat leaf rust was interpreted as a specialized form of P. rubigo-vera. Later, Eriksson and Henning (1894) classified the fungi as P. dispersa f.sp. tritici.
Zucchini yellow mosaic virus (ZYMV) is an aphid-borne potyvirus, regarded as a major pathogen of cucurbits in most regions of the world where these crops are cultivated. ZYMV affects all cucurbits including pumpkins , squashes , [ 1 ] vegetable marrows , courgettes , melons , watermelons , cucumbers , gherkins and various gourds especially ...