apple rust
nounDefinition of apple rust
1
: any of several diseases caused by fungi of the genus Gymnosporangium
especially
: a destructive fungal disease especially of the apple but also attacking pears and quinces that is caused by a rust (G. juniperi-virginianae) having its pycnial and aecial stages on the leaves and fruit of the apple and the telial stage on species of Juneperus, especially a common red cedar (J. virginiana)
2
: the fungus causing apple rust
— called also cedar apple rust, cedar rust
— compare cedar apple