Chlorosis

Definition

A physiological condition in plants characterized by insufficient chlorophyll production, resulting in yellow, pale green, or yellow-white leaf discoloration. In entomological contexts, chlorosis is frequently induced by piercing-sucking arthropods—aphids, leafhoppers, whiteflies, spider mites, and psyllids—whose feeding disrupts chloroplast function or vascular nutrient transport. The condition also names a suite of plant viruses (e.g., Tomato chlorosis virus, Bean chlorosis virus) transmitted by these vectors, where symptoms serve as field diagnostic cues for arthropod-borne disease outbreaks.

Etymology

From Greek chloros (green) + -osis (condition)

Example

Heavy infestations of the two-spotted spider mite (Tetranychus urticae) produce stippled chlorosis on bean leaves, while the whitefly Bemisia tabaci transmits Tomato chlorosis virus, causing interveinal yellowing and yield loss in greenhouse crops.

Synonyms

• yellowing
• etiolation (loose)

Related Terms

• Vector
• Phytotoxicity
• gall
• mosaic
• Necrosis
• Piercing-sucking mouthparts
• plant virus

Usage Notes

Distinguish chlorosis (yellowing from chlorophyll loss) from necrosis (tissue death, typically brown/black) and mosaic (irregular patchy discoloration from viral infection). In diagnostic entomology, pattern matters: stippled chlorosis suggests mite or lace bug feeding; vein-clearing chlorosis may indicate early viral infection; uniform interveinal yellowing can signal nutrient deficiency unrelated to arthropods. The term applies to the symptom, not the causal agent; use 'chlorotic' for the adjectival form.