264 Pflanzenkrankheiten. 



to the soft unexpanded leaves, and destroys the centre of the bud. 

 It is only at this stage that the disease becomes visible from below, 

 for the partially expanded leaves turn pale and wither, and become 

 dry and brown in from 10 to 12 days. 



Infection takes place readily by contact, and it is supposed that 

 the spores are chiefly carried by insectsand human agency. The fungus 

 can pass into a dormant condition, and recommence its growth at 

 a later date, even after two years. 



Cutting out and burning the diseased crowns has been found to 

 check the spread of the disease. E. M. Wakefield (Kew). 



Dale, E., A Bacterial Disease of Potato Leaves. (Ann. Bot. 

 XXVI. p. 133—154. Jan. 1912.) 



The author describes a disease of Potato leaves due to Bacillus 

 tubifex, n. s., which forms tubes similar to those known in the 

 root-nodules of Leguminosae. The disease is confined to the leaves, 

 the epidermis of which is pierced by the tubes. The Symptoms are 

 yellowing of the leaves, with brown patches on the lamina, and a 

 brown colouration of the veins, sometimes, but not always, accom- 

 panied by "leaf-curl". Infection only takes place in the presence of 

 water, hence usually at the ends of the veins, where drops of water 

 are excreted. Eventually the leaves shrivel, and the shoot dies. In 

 very hot dry weather the disease cannot spread, since the maximum 

 growing-temperature for the Bacillus is 35° C. 



In its reactions, and in its effects on the plant, the organism 

 differs from B. solanacearum E. J. Smith, and from B. melanoge- 

 nes P. and M. E. M. Wakefield (Kew). 



Dale, E., On the cause of "Blindness" in Potato Tubers. 

 (Ann. Bot. XXVI. p. 129—131. Jan. 1912.) 



The author shows that "blindness" in Potato tubers is caused 

 by the fungus Veriicillium albo-atrum. The mycelium is present in 

 the tubers and causes the destruction of the eyes. It grows up into 

 the new shoots, and in some cases passes into sub-aerial shoots. 

 Internally the mycelium is colourless and develops in the cortical 

 tissues, externally it is scanty and brown. Tubers may be affected 

 by means of vegative mycelium only, the course of the fungus from 

 the old to the new tuber being tracible by means of the brown 

 colouration of the affected tissues. A. D. Cotton. 



Hörne, A. S„ On Tumour and Canker in Potato. (Journ. Roy. 

 Hort. Soc. XXXVI. 2. p. 362—389. Dec. 1911.) 



A historical and comparative account of the diseases "potato 

 tumour" (Chrysophlyctis endobiotica, (Schilt.), and "potato canker" 

 Spongospora solani, Brunch.). In the bibliography, 82 references to 

 literature are given. E. M. Wakefield (Kew). 



Pethybridge, G. H., In vestigations on Potato Diseases. 

 Third Report. (Journ. Dept. Agr. Tech. Instr. for Ireland. XII. 

 n ü . 2. Jan. 1912.) 



"Blight" {Phytophthora infestans). The beneficial effect of 

 spraying is most evident when the spray happens to have been 

 applied just before a period of wet weather. Hence a succession o 

 sprayings should be arranged. Bordeaux mixture was found to be 



