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FUNGAL DISEASES THAT ARE EASY TO IDENTIFY

As noted previously, in order to accurately identify most fungal plant diseases, you need to look for and identify the spores and/or fruiting bodies produced by the pathogen. Some fungal diseases however, can be identified by eye, without the aid of a microscope.

One such disease is powdery mildew (shown in this photo on African violet). If you notice a white coating (see arrow) on the surface of the leaves or flowers of a plant that looks as if someone sprinkled the surface with powdered sugar or talcum powder, then powdery mildew is the most likely problem. The white that you see is a combination of hyphae and asexual spores.

The name powdery mildew actually describes a group of diseases that occur on a wide range of plants, and that are caused by several closely related fungi. Powdery mildew fungi tend to be relatively host specific (i.e., the fungus that causes powdery mildew on African violet is NOT exactly the same fungus that causes powdery mildew on phlox). However, if you see powdery mildew on one plant, look for it on other plants. The presence of powdery mildew on one plant indicates that environmental conditions (high humidity) are favorable for it to occur on other plants as well.