Orange Rust
Phragmidium spp.
14 host plants · Fungal
Last updated
This profile contains verified disease data from extension databases. Regional field notes and expert review are in progress.
Orange rust affects raspberry and blackberry in cool, moist regions, causing damage to bramble crops. Watch for orange-colored pustules on foliage and stems, particularly visible in warm, wet conditions. Remove affected leaves promptly and improve air circulation around plants. Consider resistant varieties where available. Spore spread is worst in wet conditions, so avoid overhead watering. This rust disease spreads readily in moist spring and fall conditions common to temperate regions. Watch foliage closely for early symptoms.
Rust fungi often need two different host plants to complete their life cycle, so identifying and managing the alternate host can break the cycle. Remove heavily infected leaves and dispose of them away from the garden. Improve air circulation to speed leaf drying after rain. Fungicide applications are most effective as preventive treatments before symptoms appear; once pustules are visible, the current infection cycle is already underway.
Quick Reference
Management
New shoot emergence (spring); March-May primary infection window when canes are actively growing. Systemic infection persists year-round on infected canes.
Cool, moist spring conditions (≥50°F) favor spore germination and infection of new shoots. Systemically infected canes show symptoms on every flush of new growth regardless of weather, but initial infection requires spring moisture.
Cultural Controls
- Remove and destroy infected plants
- Remove infected canes from disease-free plantings
- Clean up fallen leaves and canes