ABCDEFGHIJKLMNOPQRSTUVWXYZ

Diseased citrus leaves in Pohnpei exhibiting classic foliar symptoms of citrus canker disease, caused by the plant-pathogenic bacterium, Xanthomonas sp.

Diseased citrus leaves with interveinal chlorisis, a symptom of iron deficiency.

Definition

Disease is the abnormal functioning of an organism.

Etymology. c.1330, "discomfort," from O.Fr. desaise, from des- "without, away" + aise "ease". Sense of "sickness, illness" first recorded 1393; the word still sometimes was used in its lit. sense early 17c.