Gymnosporangium is a genus of heteroecious plant-pathogenic fungi which alternately infect members of the family Cupressaceae, primarily species in the genus Juniperus (junipers), and members of the family Rosaceae in the subfamily Maloideae. In junipers (the primary hosts) (see photo), the fungus forms a ball about 2- 4 cm in diameter which produces a set of orange tentacle-like spore tubes called telial horns. These horns expand and have a jelly like consistency when wet. The spores are released and travel on the wind until they infect an Apple, Pear, or Hawthorn tree. On the secondary hosts, the fungus produces yellowish depressions on the leaves. It also infects the fruit, which grows tubes like a Medusa head. These are the spore tubes. The spores must then infect a Juniper to complete the life cycle.
Fairly frequent and widespread in Britain.
Fairly frequent in Leicestershire and Rutland.
Leicestershire & Rutland Map
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