Lime-induced Chlorosis
Non-pathogenic (iron deficiency)
143 host plants
Last updated
Rhododendron foliage yellows (interveinal) on high-pH soils where iron becomes unavailable. Adjust soil pH to 4.5-6.0 by adding sulfur or acidic organic mulch like conifer needles. Use azalea-specific fertilizers containing iron. Check for proximity to new concrete, which leaches lime into soil.
Manage lime-induced chlorosis by breaking the disease cycle at the points you can control: remove infected tissue and debris, reduce moisture on susceptible foliage, and maintain plant health through proper watering and fertilization. Healthy, well-sited plants resist infection more effectively than stressed ones, so addressing underlying site conditions often solves the problem better than repeated chemical applications.
Quick Reference
Management
Cultural Controls
- Feeder roots are close to the surface, so work soil very lightly to avoid further injuring the plant.
- Adjust soil pH to 4.5 to 6.
- Adding sulfur or organic matter, especially conifer needle mulch, which is highly acidic, may help.
- Use ammonium sulfate as a nitrogen source especially if soil pH is on the high side.
- Repeated use can lower soil pH below the optimum range.
- Home gardeners should use products marketed as azalea, camellia and/or rhododendron food.