Family Pucciniaceae » Gymnosporangium sabinae (Dicks.) G. Winter
This fungi requires two different hosts to complete its life cycle from year to year. Juniper is the winter host and pear is the most common summer host. There are barnacle-like growths on the underside of the leaf, and bright yellowish to reddish-orange, rusty discoloration on the upperside. It occurs on wild pear and many cultivars. Widespread and fairly frequent in England.
Neighbour’s pear tree, South Staffordshire. 21st September 2021. Photos © Peter Hillman.