Which mold grows on plants that are coated with honeydew?

The presence of honeydew on plants often indicates an infestation by sap-sucking insects such as aphids or whiteflies. These insects excrete a sugary substance known as honeydew, which provides an ideal medium for the growth of black sooty mold. This mold appears as a dark, powdery coating on the leaves and stems of plants and can interfere with photosynthesis by blocking sunlight, ultimately harming the plant.

The other types of molds mentioned, such as powdery mildew and downy mildew, have different characteristics and causes. Powdery mildew typically arises in dry, warm weather and appears as a white, powdery substance on leaves, while downy mildew is generally more suited to cool and moist conditions, forming fuzzy white or gray patches on the underside of leaves. White mold, on the other hand, is a fungal disease that primarily affects the stems and leaves of plants but is not associated with honeydew. Thus, the association of honeydew with black sooty mold makes it the correct answer in this context.