1916] DISEASES OF PLANTS. 247 



readily between 50 and 77°, infecting either the leaves or the tubers. Experi- 

 ments are said to have shown that the loss through tuber infection is decreased 

 if the digging is postponed for a week or more after the dying of the tops, 

 except in very wet weather and on low, heavy soil, which conditions require 

 early digging. Infected tubers, though capable of spreading the disease, show 

 little or no change, the wet rots sometimes observed being due to the entrance 

 of other organisms. 



Control measures include the use of blight-free seed, complete removal of 

 material from the previous crop, rotation, spraying (which is regarded as 

 protective only), and the use of resistant stock. The variety New Era is 

 said to have yielded excellent results since its appearance several years ago. 



Biochemical studies on potato leaf roll disease. — V, The amylase of tubers 

 from plants showing leaf roll, G. Doby and J. Bodnar {Ztschr. Pflanzciikrank., 

 25 (1915), No. 1, pp. Jt-16). — The work previously reported on by one of the 

 authors (E. S. R., 28, p. 150) has been extended to a study of the amylase of 

 tubers. 



It is thought that the amylase of potatoes is present partly as zymogen, 

 which passes over continually into the active state. The activity in freshly 

 expressed sap showed no relation to the variety or origin of the potatoes 

 tested. In general, sound tubers possess more zymogen than diseased ones. 



These studies are not considered as having yet demonstrated a basal chemical 

 criterion for the presence of leaf roll, or as having decided whether the 

 chemical or biochemical changes observed in diseased tubers are the cause or 

 the effect of the disease, or how far the optimum and the activities of amylase 

 differ in sound and in diseased tubers. 



Rice smut, A. A. L. Rutgers (Dept. Landb., Nijv. en Handel [Dutch East 

 Indies], Meded. Lab. Plantenziekten, No. 11 (1914), pp. 1, figs. 2). — A descrip- 

 tion, with bibliography, is given of the grain smut of rice and of the causal 

 fungus ( Tilletia horrida ) , which is considered identical with T. corona. 



A new brown spot disease of the leaf of Glycine hispida caused by Septoria 

 glycines n. sp., T. Hemmi {Trans. Sapporo Nat. Hist. Soc, 6 (1915), No. 1, pp. 

 12-17). — The author describes a disease of G. hispida characterized by enlarg- 

 ing spots appearing on both surfaces of young leaves, which become discolored 

 and fall, the disease working toward the top of the plants and often ruining the 

 entire crop. The disease, which is due to a fungus described as S. glycines 

 n. sp., spreads most rapidly in damp, warm weather ap.d in places which are 

 incompletely drained. In a dry season or place the disease is checked, so that 

 the upper leaves are usually not attacked, but, if the favorable conditions set up, 

 the disease spreads again actively. 



The newly described fungus is compared as regards important characters with 

 S. sojina, which is said to be the only species previously noted as parasitic on the 

 leaves of soy bean. 



Injuries and diseases of tobacco in Dalmatia and Galicia in 1911, 1912, 

 and 1913, Preisseckek (Fachl. Mitt. Osterr. Tabakregie, 15 (1915), No. 1-3, 

 pp. 59-64. fl'J- !)• — III two sections dealing separately with Dalmatia and Galicia 

 as regards the causation, during this period, of losses to the tobacco intere.sts, 

 notes condensed from official reports are given on plant and animal pests, injuries 

 due to weather, abnormalities of physiological or unknown causation, and dis- 

 eases caused by fungi in various localities. 



The endoconidia of Thielavia basicola, W. B. Brierlet (Ann. Bot. [London], 

 29 (1915), No. 116, pp. 483-493, pi. 1, fig. 1).—The author gives an account of 

 his study of the conidial characters and behavior in T. basicola which are 

 thought to be typical of those in all fungi producing endoconidia. 



