Begonias are excellent plants for indoors and out with their vibrantly colored rose-like flowers or vivid, iridescent leaves they easily brighten up the darkest of shady areas. They normally grow fine with minimal water requirements and little other care but once and a while you’ll notice that your colorful friends have a white powder on their leaves and they begin to look stunted. This is powdery mildew, a fungal disease that begonias are notorious for getting during periods of warm days, cool nights and dry soil.
Powdery Mildew on Rieger Begonia
What you can do…
If your begonia is indoors you should bring it outside and cut off infected leaves. In order to prevent the disease from spreading to uninfected leave, spray the remainder of the plant with “No Powdery Mildew” fungicide.
After your plant has had some time to air out, move your plant to a new home where it will get more sunlight. Make sure to keep the soil moist as this will inhibit reinfection.