Begonia Powdery Mildew

Powdery mildew on begonias: white powdery coating on leaves/stems/flowers. Symptoms: leaf curling, distortion, yellowing, stunted growth. Causes: high humidity, poor ventilation, overcrowding. Treatment: baking soda spray, neem oil, sulfur spray, pruning infected parts. Prevention: air circulation, avoid wetting foliage.