570 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
plot of shallow-planted tubers showed a much higher percentage of diseased 
plants. Deep planting may therefore exercise a deterrent influence on the 
Bacteria.—/. E. W. E. H. 
Potato Blackleg Disease. ByW. J.Morse (Jour. Agr. Res. viii. pp. 79-126, 
Jan. 1 91 7). — This disease is prevalent in certain seasons in Great Britain, and is 
characterized by a pronounced blackening of the base of the stem. Plants 
affected are generally unthrifty and undersized, leaves and branches tend to 
grow upward instead of spreading, forming a more or less compact top, later 
becoming light green or yellow, and whole plant eventually dyings A careful 
description of the appearance and predisposing causes of the disease are given, 
as well as notes upon the geographical distribution of the disease. The author 
recommends the rigid rejection of all seed tubers in any way cracked, bruised, 
discoloured or decayed, and the disinfection by steeping in formaldehyde of all 
tubers selected for planting. He carried out a careful investigation of the 
causal bacillus, which he recognizes as identical with that described by van 
Hall, whose description he revises, Bacillus atrosepiicus, and considers Bt 
melanogenes of Pethybridge and Murphy to be synonymous.*— F. J. C. 
Potato Disease, A Form of, produced by Rhizoctonia. By G. B. Ramsey 
(Jour. Agr. Res. ix. pp. 421-426 ; June 191 7 ; plates). — Two phases of damage 
to the potato tuber occur as a result of the attack of Rhizoctonia Solani ; (1) some- 
what resembles scab and extends as a dry core into the flesh of the tuber, (2) 
the shrinkage of the tissues produces a p t in the centre of the infected area 
somewhat like the attack of wireworm. Evidence is adduced in support of 
the idea that these symptoms are produced as a direct result of the attack of 
the fungus. — F. J. C. 
Potato Diseases in Michigan. By G. H. Coons (U.S.A, Dep % Agr, Exp. Stn t 
Mick., Special Bull. 85, March 1918, pp. 1-48 ; 41 figs, in text). 
Potato Diseases in Indiana. By H. S. Jackson and G. A. Osner (U.S.A. Dep. 
Agr. Exp, Stn., Purdue, Cir, 71, Sept. 1917, pp. 1-16). — The two bulletins 
give a popular account of the commoner diseases of the potato which are fre- 
quently met with in the two States, and give detailed directions for the making 
of Bordeaux mixture for spraying purposes. 
The methods of control in general fall into three groups : (1) Sanitary and 
hygienic measures ; (2) plant protection measures ; ^ (3) the use of resistant 
varieties or strains. 
The first means clean seed in clean soil ; the second deals with spraying 
as a measure of protection ; while the third means the production of immune 
varieties. — A. B. 
Potato Diseases, Investigations of. By G. H. Pethybridge (Jour. Dep. Agr. 
Ireland, xvii., pp. 1-8 ; 1917)- — One per cent. Burgundy and Bordeaux mixtures 
were again found to be about equally efficacious with the 2 per cent, solutions 
when used against Phytophthora attack, but the latter is still regarded as to 
be preferred, mainly on the ground jthat the former needs more careful 
application. 
In comparative trials against Phytophthora attack several varieties, in which 
the foliage proved somewhat susceptible, gave a very low percentage of diseased 
tubers, but conversely ' Champion II.' and ' Northern Invincible,' which are 
resistant in a high degree so far as foliage is concerned, produced a considerable 
percentage of diseased tubers, higher even than ' King Edward VII.,' in which 
the foliage is markedly susceptible. 
Observations on the sclerotia of the Botrytis disease have failed to demon- 
strate the formation of an ascospore stage . In all cases the sclerotia on germina- 
tion have produced Botrytis spores. 
The Verticillium disease due to Verlicillium atro-album, which causes a wilt 
disease of the plant, was found to be controllable by subjecting the tubers to a 
temperature of 46 0 C. for twenty hours (and in one case the mycelium in the 
tubers was dead at the end of ten hours) . Further experiments are in progress 
with this disease. — F. J. C. 
Potato Dry-rot, Further Observations on. By G. H. Pethybridge and G. A. 
Lafferty (Set. Proc. Dublin Soc. xv. No. 21 ; June 1917). — The authors show that 
the dry-rot of potatos in the British Isles is due as a rule to Fusarium caeruleum, 
not to Fusarium Solani Sacc. Recent work has enabled the distinctions between 
the species of this difficult genus to be more clearly grasped, and at the same 
time has cast doubt upon the correctness of the nomenclature of the fungi believed 
