What can the presence of stipples and yellowish areas on leaves indicate?

The presence of stipples and yellowish areas on leaves is primarily indicative of piercing-sucking insect activity. Insects such as aphids, whiteflies, or spider mites feed on plant sap by puncturing the leaf cells with their specialized mouthparts. This feeding behavior can result in the characteristic stippling or mottling on the leaves, as the targeted cells become damaged and lose their chlorophyll, leading to yellowish patches.

In contrast, overwatering tends to cause issues like root rot and leaf drop, often manifesting as wilting rather than stippling. Improper fertilization could lead to nutrient deficiencies or excesses, causing general discoloration but not the specific stippling associated with insect damage. Similarly, root disease typically presents with root rot symptoms and may show signs of wilting or yellowing, but not the distinct leaf stippling that signifies pest activity.