NOTES AND ABSTRACTS. 
507 
5. atrovirens can withstand a wide range of temperature ; its growth is 
inhibited at 2°C. to 3°C, but it is not killed at — io°C, while its optimum is from 
2i°C. to 27°C. 
Neutral to slightly acid media are most favourable to the development of 
the fungus, but 5 per cent, of cane sugar in nutrient agar inhibits sporulation. 
The fungus enters the tuber through the lenticels and destroys the epidermis 
and corky layers, thus accelerating transpiration. Both old and young tubers 
are liable to infection when stored during winter. — A. B. 
Potato-spraying Experiments at Rush, N.Y., 1914. By F. C. Stewart (U. S.A. 
Exp. Sin., New York, Bull. 405, May 1915, pp. 333~339). — The paper details 
the potato-spraying experiments at Rush, New York, in eighty-two fields, when 
the following results were obtained : — In fifty-six unsprayed fields the spraying 
increased the yield by 15' 82 bushels an acre, or 8 per cent. ; while in twenty-six 
sprayed fields the yield increased by 13' 75 bushels an acre, or 5' 5 per cent. 
Owing to the favourable weather, potato foliage was remarkably free from 
diseases and injuries of all kinds, so that large returns from spraying were not 
to be expected. — A. B. 
Potato Stems, The Rhizoctonia Lesions on. By F. L. Drayton {Phyto- 
pathology, v. pp. 59-63, Feb. 1915 ; pi.). — The author found the mycelium of 
the fungus Corticium vagum var. Solani {Rhizoctonia) penetrating the stem and 
no doubt interfering with the upward and downward flow of the water and food 
currents. — F. J. C. 
Potato, The Verticillium Disease of. By G. H. Pethybridge {Sci. Pro. Roy. 
Dublin Soc. xv. pp. 63-92, March 1916). — The attack of Verticillium albo-atrum 
upon the potato is characterized by diseased plants being rather dwarf er than 
their fellows, having the lower leaves dead and brown, and the upper ones crowded 
into a kind of rosette. The leaflets are folded upwards and inwards, thus exposing 
their lighter lower surfaces. The wood of the vascular bundles is discoloured, 
but the stems were external^ quite sound, and most of the tubers showed a 
brown discoloured vascular ring at their heel ends. Tubers affected will probably 
produce diseased crops, and a proper rotation of crops should be maintained. 
F. J. C. 
Potato Tuber, Effect of Certain Species of Fusarium on the Composition of the. 
By L. A. Hawkins {Jour. Agr. Res. vol. vi. No. 5, May 1916, pp. 183-196). — The 
effects of Fusarium oxysporum Schlecht., and F. radicicola Wollenw., on the 
sucrose, starch, and fibre content of the potato were studied and the following 
conclusions arrived at : — 
These fungi in the potato tuber reduce the content of sugar, both sucrose 
and reducing sugar, pentosans, galactans, and dry matter. The starch and 
methyl pentosans are apparently not appreciably affected, while the crude 
fibre is not reduced. The two species of fungi secrete sucrase, maltase, xylanase, 
and diastase, but the last-named enzyme is apparently unable to act upon the 
ungelatinized potato starch. 
A list of short references is given. — A. B. 
Potato Tuber Rots Caused by Species of Fusarium. By C. W. Carpenter 
{Jour. Agr. Sci. v. p. 183 ; Nov. 1915 ; plates). — Various species of Fusarium 
have been assigned as the cause of tuber rots of the potato. An investigation 
carried out by the author on these rots adds a new one to the list, and his paper 
discusses the role of Fusarium Solani (which he regards as a weak wound parasite 
under exceptionally favourable conditions), F. caeruleum (which occurs as a 
cause of tuber rot both in Europe and America), F. Eumartii n. sp. (the cause 
of a new wet and dry rot of potatos in Pennsylvania and New York), F. radicicola 
(causing jelly-end-rot and dry-rot), F. oxysporum, F. hyper oxysporum (causing 
a soft rot in the field), F. discolor var. sulphur eum (occurring in hollows of potato 
tubers in Germany and U.S.A.), and F. trichothecioides (causing a dry-rot of 
potato tubers in the store, especially in America) . F. radicicola caused no rot at 
5o°F. ; a constant storage temperature below 50°F. would prevent the action of 
F. radicicola, L. Eumartii, and F. oxysporum. All of these and F. hyperoxy- 
sporum cause tuber-rot through wound infection. — F. J. C. 
Potato Tubers, Biological and Physiological Study of the Rest Period in. By 
C. O. Appleman {Bot. Gaz. lxi. p. 265, 1916). — This article deals with cause 
and control of the rest period. Thirty-two writers on this subject are referred 
to. There were two opposing views : Grisebach " considered the yearly 
