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Rhytisma acerinum is a plant pathogen that commonly affects sycamores and maples in late summer and autumn, causing tar spot. Tar spot does not usually have an adverse effect on the trees' long-term health. [1] R. acerinum is an Ascomycete fungus that locally infects the leaves of trees and is a biotrophic parasite. [2]
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.
Leaf spots reduce the surface area available on leaves for photosynthesis and so can result in smaller growth and yield of plants. Weakened plants may produce lesser fruit. Virus caused leaf spots reduces chlorophyll in the leaves, resulting in less photosynthetic activity.
Symptoms of infection include a downward curling of the leaves, leaf tip dieback, stunting, necrosis of growing leaf tips, sunken 'chicken pox-like' spots on leaves (often with a surrounding halo), stem death and yellowing. [7] Since these symptoms are so generic, extreme caution must be taken when introducing new plants to your greenhouse.
The leaves are used as a food plant for the larvae of a number of the order Lepidoptera (see List of Lepidoptera that feed on maples). In high concentrations, caterpillars, like the greenstriped mapleworm ( Dryocampa rubicunda ), can feed on the leaves so much that they cause temporary defoliation of host maple trees. [ 14 ]
Amur maple is treated either as a subspecies of Acer tataricum (Tatar maple), [3] or as a distinct species in its own right, Acer ginnala. [2] [4] [5] The glossy, deeply lobed leaves of subsp. ginnala distinguish it from subsp. tataricum, which has matt, unlobed or only shallowly lobed leaves; it is separated from subsp. tataricum by a roughly 3,000 km range gap across central Asia.
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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 ...