How to Get Rid of a Fungus on the Inside of a Begonia

The fungus you see on the inside of a begonia flower can be powdery mildew or gray mold. Both are common fungi that infect the leaves and blossoms of the plants, and spread easily to nearby begonias. You can treat the infection with fungicide then take further steps to prevent further spreading of the infection. Once the fungus is gone, the powdery substance on the flowers should fade.

Sulfur fungicide
Spray bottle or sprayer hose attachment
Shears

Instructions

- 1
  Spray the infected flowers and leaves with a general plant sulfur fungicide. Begin spraying as soon as the fungus appears and repeat twice weekly until the fungus is gone. Mix the fungicide with water as directed on the packaging then pour the solution into a spray bottle and apply it to the flowers. If you have more than one begonia, mix the solution in a garden sprayer and apply it with that.
- 2
  Remove all fallen leaves and flowers that have collected around the base of the plant. Discard them in the trash. Cut off any infected stems or leaves and discard them as well.
- 3
  Cut off all faded blooms, even if they do not show infection. The faded blooms can house the fungus and spread it. Space potted begonias at least 20 feet away from each other to prevent the fungus from spreading.

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