DISEASES OP PLANTS. 747 



soil conditions. Leaf roll was widoly reported in the potato districts of Colo- 

 rado for several years, but it is thought to have almost completely disappeared 

 in 1915. 



[Infection of sugar beets through, the seed], P. Sorauer {Ztschr. Pflanzen- 

 krank., 24 (1914), No. 8, pp. 449-462). — This is a discussion of the various fungi 

 and bacteria which are introduced into the soil with seed or mother beets, and 

 tlie developmental relations between these organisms and their host plants. 



Soil stain, or scurf, of the sweet potato, J. J. Taxtbenhaus {U. S. Dept. 

 A(/r., Jour. Agr. Research, 5 (1916), No. 21, pp. 995-1002, pis. ^).— The results 

 are given of an extended study at the Delaware Experiment Station of the 

 soil stain, or scurf, of sweet potatoes due to Moniloclnctcs infuscans (E. S. R., 

 2, p. 41G). This disease is said to occur in practically all sweet potato regions 

 and is abundant in heavy soils, especially where manure has been used as a 

 fertilizer. It is said to reduce the market value of the roots and also to reduce 

 the yield by attacking the young roots and stunting their development. The 

 fungus is said to be difficult to culture, as it is of very slow growth and readily 

 overgrown by associated saprophytes. A description of the fungus as obtained 

 from pure culture is given. 



[Practical protection for plants], Junge (Ber. K. Lehranst. Wein, Obst u. 

 Gartcnbau GcisenJieim, 1913, pp. 27-30). — American gooseberry mildew appears 

 to have been dealt with effectively by careful removal of affected tips and 

 thorough pruning with a view to light admission. 



Fusicladium was not controlled by use of Bordeaux mixture or of lime sul- 

 phur. 



The use of heating devices for preventing injury to orchard fruits was not 

 effective when the temperature sank as low as — 4° C. 



Fire blight, L. R. Tehon (Bien. Rpt. W}io. Bd. Hort., 5 (1913-14), pp. 59-64, 

 fiffs. 3). — It is stated that fii-e blight (Bacillus amylovorus) is fast getting a 

 hold upon the orchard district of Wyoming, practically every orchard in Crook 

 (^ounty being infected in 1914. 



Tlie transmission, symptoms, and progress of the disease are discussed. 

 Trees in vigorous growth, forming abundant new, succulent tissue, are par- 

 ticularly susceptible. The organism can not endure severe drying. 



Continual inspection with destruction of all infected material constitutes the 

 only available means of protection. The organism overwinters in the cank'ers 

 on the fruit trees, and on mountain ash, service berry, and haw. 



Dusting nursery stock for the control of leaf diseases, V. B. Stewart (New 

 York Cornell Sta. Circ. 32 (1916), pp. 10, figs. 5). — On account of the reported 

 success of dusting apple orchards for control of diseases the author has investi- 

 gated the practicability of this treatment for the control of leaf diseases of 

 cherry, rose, currant, and horse-chestnut. The dust mixture used in all the 

 experiments was composed of 90 parts of finely ground sulphur and 10 parts 

 of powdered lead arsenate. The results obtained were so successful that 

 further trial on a more extensive scale is considered advisable. 



The use of lime sulphur as a summer spray for apple scab, C. C. Vincent 

 (Idaho Sta. Bui. 84 (1915), pp. 26, 211). — A l)rief preliminary report is given of 

 the results of spraying for the control of apple scab. Three applications of lime 

 sulphur resulted in a crop 95 per cent of which was sound, as comi^ared with 

 10 per cent from untreated trees. The applications were made when the buds 

 began to show pink, when the petals fell, and four weeks later. 



Plum wilt, its nature and cause, B. B. Higgins (Georgia Sta. Bui. 118 

 (1916), pp. 3-29, figs. 25). — A disease of .Japanese plums and of hybrid varieties 

 of Japanese parentage, known as wilt, is said to have been under observation 



