Pear Trellis Rust (also called European Pear Rust has been in the Lower Mainland and southern Vancouver Island since the 1950’s. It has been recently spread into the Okanagan where it has been found in a small number of locations. It is also in Washington State, Ontario and parts of Eastern USA. All pear trees and many species of junipers can be affected by the disease.
Pear Trellis is a fungal rust disease. This disease has obligatory alternate hosts which means: Infected Junipers produce spores in the spring that infest pear trees growing within about 150 meters. In the summer infected pear trees produce spores that infect Junipers growing within about 150 meters. If one of the two hosts is removed from the area of the other, the disease will disappear in that area.
This disease annoys gardeners and many trees have been removed to avoid it. Removing trees is rarely necessary. Unless the infection level is very high this is a cosmetic disease and should be ignored. There are no organic fungicides that will control this disease. The best solution if you only have a couple of small pear trees is to pick off the infected leaves mid summer as this will prevent reinfection of junipers. The wide distribution of this disease in this area will cause some reinfection each year.