NOTES AND ABSTRACTS. 



695 



one, as in strains showing a tendency to form thread-sprouts the disease 

 may appear at any future time. 



The only certain cure is the occasional recourse to sexual reproduction, 

 that is by seed, whereby the original stamina and power of adaptability are 

 restored. — G. M. 



Potato Disease, A new. Anon. (Gard. Mag. No. 2607, p. 691 ; 



17/10/03). — A parasitic fungus known as Chrysophlyctis endobiotica is 

 described and illustrated. It attacks the tubers and roots, and is said to 

 be very destructive in its most virulent forms. It is said that it has found 

 its way to this country from Upper Hungary, where it was first noticed by 

 Schilberszky.— W. G. 



Potato Disease: Rosette, Rhizoctonia. By A. D. Selby (U.S.A. 



Agr. Exp. Stn. Ohio, Bull. 139, April 1903 ; 5 figs.). — This disease is 

 characterised by the early dying of the Potato vines before the formation 

 of many tubers, the underground parts appearing to be the seat of the 

 disease agency, while the excessive branching in some, and in general a 

 conspicuous clustering of these branches or of the terminal leaf groups, 

 together with the early dying of the entire tops, are the conspicuous above- 

 ground characters. In examples examined, the stems above ground 

 showed occasional discoloured areas of soft decay, while below the soil 

 surface were numerous lesions in the form of brown dead areas. The 

 diagnostic features in this malady arise from the changes in the stem by 

 reason of its lesions below ground, or near the surface above ground, and 

 from the peculiar branching or clustering of the leaves. Upon micro- 

 scopical examination of fresh material, the apparently constant presence of 

 the hyphae of the fungus Bhizoctonia solani (Kuehn) was revealed. In 

 1902 the sclerotia of the fungus to which the disease is attributed were 

 found in abundance upon tubers where the disease prevailed. 



The sterile fungus Bhizoctonia is indicated as the cause of the disease 

 in the cases examined by its constant presence, to which a high degree of 

 probability is attached. It is found on the seed tubers which produce 

 diseased plants ; such tubers, when stored in a warm place, have been grown 

 to the production of elongated, etiolated, leafless stems, destroyed at the 

 summit by the Bhizoctonia. The fungus grows vigorously in cultures, 

 producing no clearly recognised spore-forms, but dense masses of the 

 fungus threads or hyphae. These masses, which are dark brown to almost 

 black in colour, are capable of surviving under adverse conditions, and of 

 growing and reproducing the fungus in a purely vegetative manner. 



The warranted conclusion, drawn from tests of two seasons with 

 formalin and corrosive sublimate, appears to be that corrosive sublimate 

 seed treatment does not prevent the rhizoctonia disease to any appreciable 

 extent, while the formalin seed treatment, as shown conspicuously by study 

 of the growing plants, does prevent the disease to a very marked extent. 



The formalin treatment is as follows : 



Add \ pint of formalin (40 per cent, strength) to 15 gallons of water, 

 soak the seed tubers in it for two hours, then cut and plant. — M. C. C. 



Potato Diseases and their Remedies. By L. R. Jones and W. J. 

 Morse (U.S.A. Exp. Stn, Vermont, Ann, Bep. 1901-1902, p. 209).— The 



