Powdery mildew: Erysiphe chichoracearum and Oidium erysiphoides f.sp. gerbera

Symptoms

• The fungus forms white powdery coating on the foliage. 

Management

• Spraying with 0.2% Wettable sulphur controls E. Chichoracearum.
• Diseased leaves should be removed and destroyed.

Image source:

http://www.gerbera.org/tag/diseases/