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Black rot, leaf spot and canker Botryosphaeria obtusa Sphaeropsis malorum [anamorph] Black spot (of Japanese pear) Alternaria alternata. Blister canker Helminthosporium papulosum. Blister disease Coniothecium chomatosporum: Blue mold rot Penicillium spp. Penicillium expansum. Botrytis spur and blossom blight Botrytis cinerea
Like many rusts, G. sabinae requires two different hosts to complete its life cycle from year to year. Juniper is the winter host and pear is the summer host. Spores (called aeciospores) are produced from the fungal lantern-shaped growths which protrude from the blisters on the underside of the pear leaf which become airborne and infect junipers.
In southern Germany apple and pear trees have been a part of the landscape for a long time, and are difficult to protect. The decline of apple and pear trees from their landscape can be expensive to replace and could have a negative effect on tourism. In the long-run, fire blight is a very important factor of economy and society. [citation needed]
Pyrus calleryana, also known as the Callery pear or Bradford pear, is a species of pear tree native to China and Vietnam, [2] in the family Rosaceae. It is most commonly known for its cultivar 'Bradford' and its offensive odor, widely planted throughout the United States and increasingly regarded as an invasive species .
Stroma is located in the black lesions of the infected leaves. [2] Conidiophores form non-infectious conidia that are released both in conditions of wetness and drought. [ 2 ] [ 7 ] The most favorable environment for the pathogen is when there is an extended period of moisture such as fog or rain, which prevents the leaves from drying out. [ 8 ]
On the apple tree, the infections occur on leaves, fruit and young twigs. [4] The brightly colored spots produced on the leaves make it easy to identify. Small, yellow-orange spots appear on the upper surfaces of the leaves, anytime from April to June. [5] These spots gradually enlarge and turn orange or red and may show concentric rings of color.
The cause of brown leaf spot disease affecting pear trees in South Korea was first identified as a novel bacterial infection in 1990. The proposed name for the species was Erwinia pirina, but this name was not validly published.
Chondrostereum purpureum is a fungal plant pathogen which causes Silver leaf disease of trees. It attacks most species of the rose family Rosaceae, particularly the genus Prunus. The disease is progressive and often fatal. The common name is taken from the progressive silvering of leaves on affected branches.