Necrotic Ringspot
Rhododendron necrotic ringspot virus
133 host plants
Last updated
This profile synthesizes data from multiple published sources. Expert field review is in progress.
Leaves develop circular dead zones or concentric rings of necrosis from viral infection of the plant tissue throughout the canopy. No cure exists for viral diseases; remove infected plants entirely to prevent further spread to adjacent plants. Use clean planting material from certified virus-free sources for all new plantings.
Remove and destroy symptomatic plants. Do not propagate from plants showing symptoms. Improve drainage around susceptible plants and avoid overwatering. Remove affected material and dispose of it away from the garden. When replanting, choose resistant varieties and amend the soil for better drainage if waterlogging was part of the problem.
Quick Reference
Management
Infection occurs during early spring or late summer/fall when propagation and grafting typically occur. Symptoms appear on 2-year-old leaves the following growing season, typically becoming visible by mid-summer (June-July). Annual symptom recurrence on 2-year-old growth provides diagnostic indicator. Young plants infected via seed or propagation show symptoms within 2 years. Once infected, plants remain infected indefinitely. Seed-infected plants show symptoms at seedling stage or first growing season. Source: PNW Plant Disease Management Handbook
Symptom expression primarily visible on 2-year-old leaves; current-season growth and flowers remain unaffected. Necrotic rings become apparent and increase in number during growing season. Infected leaves turn red or yellow and drop prematurely. Sunlight exposure may influence symptom development and visibility. Environmental stress may affect symptom severity. Plant vigor loss indicates systemic infection. Cool, moist spring conditions (typical for PNW) may favor symptom expression. Source: PNW Plant Disease Management Handbook
Cultural Controls
- Remove and destroy symptomatic plants.
- Do not propagate from plants showing symptoms.
- Reference Coyier, D.L., Stace Smith, R., Allen, T.C., and Leung, E. 1977.
- Viruslike particles associated with a rhododendron necrotic ringspot disease.
- Phytopathology. 67. 1090-1095.