Which term describes an abnormal swelling of plant tissue caused by microorganisms or insects?

The term "gall" specifically refers to an abnormal swelling or growth of plant tissue that occurs as a result of infection by microorganisms or feeding by insects. Galls can form on a variety of plant parts, including leaves, stems, and roots. They are often the result of the plant's response to the presence of a pathogen or pest, leading to uncontrolled growth in the affected area.

Galls can be caused by a variety of organisms, including certain fungi, bacteria, viruses, and insects like gall wasps. This term is important in both plant pathology and entomology, as it indicates a specific type of plant response to biotic stress. In contrast, other terms listed, such as "blight," refer to a disease characterized by rapid and extensive decay of tissues, "chlorosis" describes a condition of yellowing due to insufficient chlorophyll, and "necrosis" refers to the death of cells or tissue, all of which are distinct from the growth and swelling indicated by galls. Recognizing this specific terminology helps in diagnosing plant health issues and understanding the interactions between plants and pests.