Bacterial Leaf Spot
Xanthomonas spp.
7 host plants · Bacterial
Last updated
This profile contains verified disease data from extension databases. Regional field notes and expert review are in progress.
Circular brown spots with yellow halos form on leaves, reducing photosynthesis. This bacterial disease spreads by rain splash. Avoid overhead watering and space plants.
Leaf spot and blotch diseases are primarily cosmetic on established plants, though repeated years of heavy infection can weaken them. Rake up and remove fallen leaves to reduce the spore load going into the next season. Avoid overhead watering that splashes spores from the ground onto lower leaves. If the problem is severe, protective fungicide sprays during spring leaf emergence can help, but sanitation does more than chemistry for most leaf spots.
Quick Reference
Management
Growing season during warm humid periods with frequent leaf wetness. Young expanding leaves are most susceptible. Disease pressure is highest in nursery production where overhead irrigation and plant density are common." # Source: PNW Plant Disease Management Handbook
Warm humid weather; overhead irrigation; leaf wetness; poor air circulation; crowded plantings. Xanthomonas spp. thrive in warm, moist environments. Rain and overhead irrigation are the primary dispersal mechanisms." # Source: PNW Plant Disease Management Handbook
Cultural Controls
- Remove and destroy infected leaves and plant debris to reduce inoculum sources." # PNW Plant Disease Management Handbook
- Avoid overhead irrigation; use drip irrigation to minimize leaf wetness." # PNW Plant Disease Management Handbook
- Space plants to provide good air circulation and reduce humidity around foliage." # PNW Plant Disease Management Handbook
- Sterilize pruning tools between cuts to prevent spread." # PNW Plant Disease Management Handbook
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Host Plants (7)
Sources & References
Primary: PNW Plant Disease Management Handbook
- PNW Plant Disease Management Handbook