. Circular. Agriculture; Agriculture -- United States. SILVER SCURF, A DISEASE OF THE POTATO. 19 This disease was called " Fleckenkranklieit " and also " Phellomyces- Faule" by Frank in 1897 and 1898, respectively. It can hardly be considered a spot disease, since it very often involves the whole surface of the diseased tuber. Recently it has been shown by Appel and Laubert that PlieUomyces sclerotiopJiorus, the fungus described by Frank, is only the sclerotial stage of Spondylocladium atrovirens. This fact naturally excludes the possibility of using the name applied to thi
. Circular. Agriculture; Agriculture -- United States. SILVER SCURF, A DISEASE OF THE POTATO. 19 This disease was called " Fleckenkranklieit " and also " Phellomyces- Faule" by Frank in 1897 and 1898, respectively. It can hardly be considered a spot disease, since it very often involves the whole surface of the diseased tuber. Recently it has been shown by Appel and Laubert that PlieUomyces sclerotiopJiorus, the fungus described by Frank, is only the sclerotial stage of Spondylocladium atrovirens. This fact naturally excludes the possibility of using the name applied to this disease by Frank. More recently the disease under consider- ation has been called " scab," " dry rot," '' dry scab," and '' ; It does not seem wise nor justifiable to apply the term "scab" to this disease, since we already have three or four different kinds of scab. Furthermore, Spondylocla- dium does not cause symptoms comparable to those produced by Oospora, Spongospora, and Chrys- ophlyctis. As is well known, all of these parasites cause hypertro- phy and cankers of the tissues in- fected. Such is not the case with Spondylocladium. On the con- trary, it causes the death and shrinkage of the attacked cells and tissues. The term "scurf" has been applied by Clinton and is doubtless a better name than any used previously, because it is less confusing and is more de- scriptive of the symptoms of the disease. The light, glistening, silvery discoloration of the sur- face of the washed potato due to the Spondylocladium infection is a very common and characteristic symptom. In view of this fact the name "silver scurf" is proposed for this Fig. 4.—Sclerotia of silver scurf, (a) The surface view of aa infected area, showing the sclsrotia and their relation to the outer layer of cells. (6) An isolated sclerotium, much enlarged, in the early stages of germination. (After T. Johnson.) DISTRIBUTION OF THE DISEA
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