gummosis

thumb|283px|Canker-induced gummosis on a Tibetan cherry Gummosis is the formation of patches of a gummy substance on the surface of certain plants, particularly fruit trees. This occurs when sap oozes from wounds or cankers as a reaction to outside stimuli such as adverse weather conditions, infections, insect problems, or mechanical damage. It is understood as a plant physiological disease.

==Damage== Liquefaction of wood pieces, especially young wood, causes disease foci to form under the bark, which secrete a gummy colorless to amber liquid, a plant gum, which then oozes out between the bark pieces on branches and trunk. The gum is composed of various sugar compounds and acids.