. Better fruit. Fruit-culture. Pa"C iJ BETTER FRUIT JanUiirv Crown Gall, Black Knot, Plant Tumor or Plant Cancer 11> THK (liscMse c;ille<l crown gall, black knot, plant tumor or plant cancer has f^or many years been well known to the horticulturist and plant pathologist. It is only within a lew years that the cause of the trouble has been thoroughly investigated by Dr. Erwin F. Smith and his associates of Ihe United .Slates Department of Agri- culture, and their bulletins are avail- able to any who may be especially in- terested in this trouble. Crown gall is nearly world-wide
. Better fruit. Fruit-culture. Pa"C iJ BETTER FRUIT JanUiirv Crown Gall, Black Knot, Plant Tumor or Plant Cancer 11> THK (liscMse c;ille<l crown gall, black knot, plant tumor or plant cancer has f^or many years been well known to the horticulturist and plant pathologist. It is only within a lew years that the cause of the trouble has been thoroughly investigated by Dr. Erwin F. Smith and his associates of Ihe United .Slates Department of Agri- culture, and their bulletins are avail- able to any who may be especially in- terested in this trouble. Crown gall is nearly world-wide in its distribution, being found in all parts of the United .States, in Canada, South Africa, Asia, countries of Europe, New Zealand, Australia, Mexico and prob- ably also in South America. The malady is a serious one on many of our (trchard trees, as it not only decreases their vigor and pi-oductiveness, but at length is a frequent cause of their death. A large number of different species of trees are susceptible. In fact the organism causing the disease is almost omnivorous as to its choice of its host, but it is especially severe in the more important econon)ic trees, such as the apple, almond, apricot, cherry, grape, |)each, i)lum, prune and walnut. The disease, when once seen, is eas\ to identify, as it is characterized by an enlargement or growth of soft, spongy tissue of a more or less spherical shape. These growths are usually situated just below the surface of the ground in the trunk or body of the tree, often ex- tending deai- to year until a large ex- cresence may be formed. The tissue produced is abnormal and easily de- cays, making an esjjecially favor;ible place for wood-destro.\ ing fungi to gain an entrance to the tree. While the galls are usually below the ground, occasion- ally aerial ones are formed on the trunk and large branches. These are hard and cause little or no serious efl'ects on the tree, except when they may be nu- merous, as on grapes of the Vinif
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