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Leaf spots can vary in size, shape, and color depending on the age and type of the cause or pathogen. Plants, shrubs and trees are weakened by the spots on the leaves as they reduce available foliar space for photosynthesis. Other forms of leaf spot diseases include leaf rust, downy mildew and blights. [4]
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 ...
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.
What they look like: Chiggers, a type of small mite, typically leave clusters of bites that are often very itchy. In many cases, chigger bites appear as small, red and itchy bumps. Sometimes, they ...
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 ...
Things as simple as leaving a layer of fallen leaves or mulch in place provides a suitable food source for worms and provides a shelter for insects, in turn being a food source for such beneficial mammals as hedgehogs and shrews. Compost piles and stacks of wood can provide shelter for invertebrates and small mammals.
Overall, very little is known about the Canna viruses, but the following points are generally accepted: . It manifests itself in rust coloured streaks or mottled markings on the leaves and in colour breaks on the flowers.
The lesions continue to grow, and by the end of summer form leaf spots that look like tar. [2] The spot can grow up to 1.5 inches (4 cm) in diameter. [4] A microscopic sign of the pathogen are the stroma, mats of hyphae found in the lesions. [2] These lesions can cause senescence of leaves but are mostly of cosmetic importance.