Marginal leaf necrosis
Xylella fastidiosa
0 host plants · Bacterial
Last updated
Leaf edges brown and die back progressively, often from water stress during dry periods or low potassium availability in the soil. Maintain consistent watering throughout the entire growing season and check soil fertility with a professional soil test. Ensure good drainage to prevent root stress and anaerobic conditions. Potassium fertilizer applications may help if deficiency is confirmed by testing.
Good sanitation is your most effective tool against marginal leaf necrosis. Remove and dispose of infected plant material, clean up fallen debris, and sterilize your pruning tools between plants. Reduce leaf wetness by watering at soil level and spacing plants for adequate air movement. These practices reduce the pathogen load in your garden over successive seasons.
Quick Reference
Management
Growing season when vector insects are active and temperatures support bacterial multiplication. Symptoms intensify during hot, dry conditions when water demand exceeds what blocked xylem can deliver." # Source: PNW Plant Disease Management Handbook
Warm temperatures above 60°F required for bacterial multiplication. Vectored by xylem-feeding insects (sharpshooters, spittlebugs). Mild winters that stay above 25°F allow overwinter survival in host xylem." # Source: PNW Plant Disease Management Handbook
Cultural Controls
- Diagnose cause before implementing management. Laboratory testing (PCR or culture) may be necessary to confirm or exclude Xylella fastidiosa." # PNW Plant Disease Management Handbook
- If bacterial (Xylella confirmed): remove infected plants to prevent spread. Monitor for xylem-feeding insect vectors (sharpshooters, spittlebugs) during the growing season." # PNW Plant Disease Management Handbook
- If abiotic: provide consistent deep watering during dry periods; avoid overwatering in poorly drained soils." # PNW Plant Disease Management Handbook
- If abiotic: avoid excess fertilizer, particularly high-nitrogen applications during hot weather." # PNW Plant Disease Management Handbook
- If abiotic: improve drainage with organic matter amendments or raised beds; apply 2-3 inches of organic mulch over the root zone." # PNW Plant Disease Management Handbook
- If abiotic: avoid herbicide applications near susceptible plants or when drift is likely." # PNW Plant Disease Management Handbook
Xylella fastidiosa is not a significant concern in the maritime Puget Sound region. Cold winter temperatures regularly below 25°F limit Xylella survival. The primary vectors (glassy-winged sharpshooter) are not established in Washington State. Marginal leaf necrosis observed here is typically abiotic — drought stress, excess heat, poor drainage, overfertilization, herbicide drift, or root damage. Evaluate symptoms in context of recent weather, watering practices, and fertilizer history before considering a bacterial cause." # Source: PNW Plant Disease Management Handbook; USDA APHIS distribution data