GUMMO'SIS (from Lat. gummy, Gk. sb,Ligt, kommi, gum), GUMMING, or Gum FLux. Any plant disease in which gum flows from the dis eased area or its vicinity. There are many different diseases of this character, which have been noticed upon many species of plants, as shown below. The gum, according to Sorauer, is a combination of metagummic acid and lime. When it first ap pears it is soft, translucent, and gelatinous, but becomes hard, horny, and brittle upon standing, and very dark brown or nearly black. Fungi and bacteria seem associated with the gummosis of many trees, hut they are perhaps-secondary to some cause like insufficient nutrition, wounds, etc. Poor soil and superabundant moisture are believed by some to cause a flow of gum in some plants. On the other hand, there seems abundant evidence that diseases caused by bac teria produce gummosis of grape, olive, sugar beet, sugar-cane, etc., and the gummy deposits noticed in the fire-blight of pears and bacterial wilt of cucurbits. A common form of gum mosis of cherry and other stone fruits is caused by the fungus Ascospora beyerinekii. This fun
gus call live in and kill the leaves and young fruits of these trees. In the Japanese quince ( Py ruR japonica) the tears of gum accompany the attacks of Cladosporium epiphyllum. If broken off, a canker-like wound is revealed, which may extend often to the pith of the stein. In Cali fornia a gummosis of citrus trees is said to be due to the presence in the trees of the mycelium of one of the mushroom fungi. In the case of many of these diseases, pruning below the gum deposits may he of some service in checking the disease. When wet, the gum dissolves and flows to the ground, carrying spores with it. To destroy these a dressing of lime at the base of the tree is recommended. In those forms of gummosis due to errors in cultivation, restoring the necessary functions of the plants should correct the dis ease. For wounds of insects, etc., coat the wounded surface with tar or some similar ma terial.