What is the term for a white cottony coating on plant leaves that causes them to turn black and wrinkled?

The phenomenon described as a white cottony coating on plant leaves that ultimately results in them turning black and wrinkled is characteristic of mildew, specifically a type of mildew known as downy or powdery mildew, depending on the specific plant disease affecting the foliage. However, the broader term "mildew" encompasses these various forms.

Mildew is a general term used to refer to a range of fungal diseases that manifest as a white or grayish coating on plant surfaces. These fungal infections can interfere with the plant's ability to photosynthesize effectively, leading to a deterioration of its health, evidenced by discoloration and wrinkling of the leaves.

In this context, the focus is on the generic application of the term "mildew," which serves as a foundational description of these fungal growths, whereas the more specific terms pertain to particular types of mildews with differing characteristics and symptoms. Understanding this distinction is crucial for identifying and managing plant diseases effectively.