abstract:Gymnosporangium sabinae (also Gymnosporangium fuscum and other names) (pear rust, European pear rust, or pear trellis rust) is a fungal heteroecious plant pathogen with Juniperus (Juniper trees and shrubs) as the primary (telial) host and Pyrus (pear trees), Malus (apple trees), or Crataegus (hawthorn) as secondary (aecial) hosts. It is one of many types of rust fungi affecting plants.