What disease is characterized by a white powdery fungal growth on leaves and stems?

• A. Bacterial blight
• B. Rust
• C. Downy mildew
• D. Powdery mildew

Answer: (D)

The symptom described—white powdery growth on leaves and stems—points to powdery mildew, a fungal disease that forms characteristic white, talc-like colonies on plant surfaces. These powdery patches are usually most evident on the upper leaf surfaces and can extend to stems. This appearance is distinct from rust, which creates orange or brown pustules, and from downy mildew, which shows a fuzzy white or gray growth often on the underside of leaves accompanied by yellowing. Bacterial blight produces water-soaked spots and ooze rather than a powdery coating. So the white powdery growth specifically identifies powdery mildew.