Sunburn Vs Fungal Spots on rubber plant
What's Happening
Accurate diagnosis requires distinguishing between three common conditions causing leaf discoloration: sunburn creates uniform brown patches on light-exposed surfaces without yellow halos; fungal infections produce irregular spots with distinct yellow margins that spread; and bacterial infections create water-soaked lesions turning necrotic. Misdiagnosis leads to inappropriate treatment—pruning for sunburn or shade for fungus—worsening the condition.
How to Fix It
- 1
Assess light exposure: direct sun for >2 hours daily indicates sunburn probability
- 2
Examine spot pattern: fungal/bacterial show irregular margins with halos; sunburn is uniform
- 3
Check leaf undersides for webbing (mites) or fuzzy growth (fungal sporulation)
- 4
Perform tissue test: sunburned tissue is dry/crispy; infected tissue is soft/mushy
- 5
Treat based on diagnosis: relocate for sunburn, fungicide for fungus, prune for advanced infection
What You'll Need
How to Prevent It
Document lighting conditions with light meter app (target 2000-4000 lux). Inspect new plants weekly for early spot detection. Maintain quarantine protocols for new acquisitions. Improve airflow to prevent fungal establishment.