Gixmmosis and Psorosis of Citrus Trees, with Special Reference to Their Cause and Control

Gummosis and psorosis are destructive bark diseases of Citrus trees found in ttliany groves throughout the state and of such widespread occurrence in certain sections as to cause considerable alarm on the part of growers. Many growers term the disease gummosis when there is a pronounced exudation of gum and scaly bark when there is a dry scaling off of the outer bark without much gum formation. . Others make no distinction between gummosis and psorosis but call all bark diseases that cause a loosening and scaling off of the bark, accompanied by more or less gum formation, by the gen eral term of "gummosis." In Florida, however, the name ''scaly bark"is reserved for another and entirely different Citrus disease known also as nail-head rust when it occurs on the fruit. The general con fusion on the part of growers in dis tinguishing between gummosis and pso rosis is perhaps pardonable since the de scriptive accounts of these respective dis eases have been more or less confused in the past and psorosis has been considered by some as merely a form of gummosis.