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Erysiphe platani, also known as sycamore powdery mildew, is a fungus native to North America that now infects sycamore tree species worldwide. [2] Infections may spread rapidly in urban settings with large groups of young trees or in plant nurseries. [3] This mildew thrives when there are high humidity conditions during the growing season. [4]
Powdery mildew is a fungal disease that affects a wide range of plants. Powdery mildew diseases are caused by many different species of ascomycete fungi in the order Erysiphales . Powdery mildew is one of the easier plant diseases to identify, as the signs of the causal pathogen are quite distinctive.
Only young developing leaves are susceptible to colonisation by E. alphitoides.It only induces necrosis when infection occurs very early during leaf development. Because the pathogen develops late in spring, after the first leaves of oak seedlings have developed, it is more prevalent on the second and third flushes of leaves that develop in July and August.
The powdery mildew initially appears as white, powdery spots formed on leaf surfaces, shoots, and sometimes flowers or fruits. Over time, the spots spread over a larger area of leaves and stems. Eventually, leaves infected with powdery mildew may turn yellow in color and proceed to die or fall off.
In most powdery mildews only the epidermal cells are attacked. The external mycelium gives rise to short, erect conidiophores, each of which bears a single row of barrel-shaped spores, the youngest being at the base (the affected parts become thus covered with a forest of conidiophores assuming a white powdery appearance). The ripe spores ...
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Powdery mildew, a biotrophic Ascomycete fungus. Most phytopathogenic fungi are Ascomycetes or Basidiomycetes. They reproduce both sexually and asexually via the production of spores and other structures. Spores may be spread long distances by air or water, or they may be soil borne.
Hybrids were created and released by the U.S. National Arboretum beginning in the 1950s, and are valued for their cold hardiness, their resistance to powdery mildew, and their striking patterned bark. [2] [4] Hybrid cultivars are all named for Native American tribes. [7]