Gymnosporangium

About

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 Amygdaloideae. The common name cedar-apple rusts has been used for these fungi. According to the Dictionary of the Fungi, there were 57 species in the genus. In 2023, Species Fungorum lists up to 74 species.

Summary from Wikipedia