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Gymnosporangium juniperi-virginianae is a plant pathogen that causes cedar-apple rust. [1] In virtually any location where apples or crabapples and eastern red cedar (Juniperus virginiana) coexist, cedar apple rust can be a destructive or disfiguring disease on both the apples and cedars.
36 species and 4 hybrids are accepted. [2] The genus Malus is subdivided into eight sections (six, with two added in 2006 and 2008). [citation needed] The oldest fossils of the genus date to the Eocene (), which are leaves belonging to the species Malus collardii and Malus kingiensis from western North America (Idaho) and the Russian Far East (), respectively.
Viral diseases; Apple chlorotic leafspot genus Trichovirus, Apple chlorotic leafspot virus (ACLSV) Apple dwarf (Malus platycarpa)
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]
Malus baccata is an Asian species of apple known by the common names Siberian crab apple, [2] Siberian crab, [3] Manchurian crab apple and Chinese crab apple. [ 4 ] [ 5 ] [ 6 ] It is native to many parts of Asia, but is also grown elsewhere as an ornamental tree and for rootstock .
Apple scab is a common disease of plants in the rose family that is caused by the ascomycete fungus Venturia inaequalis. [1] While this disease affects several plant genera, including Sorbus, Cotoneaster, and Pyrus, it is most commonly associated with the infection of Malus trees, including species of flowering crabapple, as well as cultivated apple.
A separate project was initiated by C.S. Crandall of the University of Illinois to breed scab-resistant apples by introducing the VF gene from the crabapple Malus floribunda. His work has been continued by the PRI disease resistant apple breeding program with great success. [5] Among the scab-resistant apples that carry the VF gene are ...
The wild apple is a deciduous small to medium-sized tree, but can also grow into a multi-stemmed bush. It can live 80–100 years and grow up to 14 metres (46 feet) tall with trunk diameters of usually 23–45 centimetres (9– 17 + 1 ⁄ 2 inches), although diameters exceeding 90 cm (35 in) have been recorded. [ 2 ]