Pacific Coast Pear Rust
Gymnosporangium libocedri
4 host plants · Fungal
Last updated
This profile synthesizes data from multiple published sources. Expert field review is in progress.
Pacific coast pear rust affects pear trees and relies on juniper as an alternate host. Pear fruit become malformed while young and drop from the tree. Remove infected alternate hosts around orchards when possible. This rust spreads by spores in wet weather. Improve air circulation and reduce leaf wetness to manage disease spread during vulnerable periods. This rust disease spreads readily in moist spring and fall conditions. Watch foliage closely for early symptoms.
Remove alternate hosts around the orchard. Separating hosts by 0.5 to 2 miles has been recommended. Identify and manage the alternate host if one exists. Remove heavily infected tissue and clean up fallen debris. Preventive fungicide applications before the infection window offer the best chemical control.
Quick Reference
Management
In western Oregon, the critical infection window aligns with pear bloom (typically April), when cedar telia are swollen and releasing basidiospores. Fungicide applications must coincide with this window to be effective.
Wet spring weather triggers telia swelling and spore release from incense cedar. Infection of pear occurs during bloom when spores land on susceptible tissue.
Cultural Controls
- Remove and destroy cedar brooms before spring to reduce inoculum
- Remove alternate hosts around the orchard; separating hosts by 0.5 to 2 miles recommended
- Avoid overhead irrigation that keeps foliage wet during the infection window