876 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



If rejection and storage cannot be carried out as recommended, sell 

 soon after digging. 



When there is any suspicion, buyers should always keep the Potatos 

 in cold storage. 



Stake the soundest, best looking plants on diseased fields, and save 

 the tubers from such plants for further experiment in the hope of origi- 

 nating resistent strains. — M. C. C. 



Potato, Early Blight (in Nat. Zeit. Land-Forst. ii. ; 1904).— 



This disease is well known in America and Europe under the names of 

 early blight or leaf -curl. The symptoms somewhat resemble the better 

 known epidemic (Phytophtliora), but the way in which the leaves dry up 

 is distinct, and the fungus causing the latter disease is absent. Professor 

 Tubeuf, in a short paper (pp. 264-269) with six illustrations, shows four 

 leaf diseases of Potato recognised in America, viz. epidemic, early 

 blight, leaf- spot (due to spraying with arsenic compounds), and leaf- curl 

 (due to excessive heat or drought). In regard to early blight, mycologists 

 have agreed that it is caused by a fungus, but have not agreed as to the 

 precise nature of that fungus. Species of Macrosporinm, Sporidesmium, 

 Alternaria, Cladosporium, and others have been blamed. Professor J. 

 Vanha (pp. 113-127) investigated the fungus, and states that it passes 

 through several phases in its life-history ; if this be confirmed it will go 

 far to clear up confusion. The fungus (Sporidesmium solani various, 

 n. sp.) may reproduce itself by : (1) macrospores, which resemble 

 Macrosporiuiu or Alternaria; (2) conidia, the Cladosporium stage; (3) 

 pycnidia, Phoma or Septoria stage. Four plates containing 150 

 drawings show these stages clearly, and an excellent photograph shows a 

 diseased leaf. As a severe attack of early blight results in small tubers, 

 poor in starch, the disease is a serious one. Spraying with 1 per cent. 

 Bordeaux mixture at intervals of two or three weeks has been found 

 effective. It is also recommended to burn all haulms after harvest, to 

 plough the field deeply, and to avoid Potatos as a crop in the field for 

 several years. — W. G. S. 



Potato Rosette. By A. D. Selby (U.S.A. Dep. Agr. Exp. Stn. Ohio, 

 Bull. No. 145, Nov. 1903 ; 4 figs.). — Further investigations are here 

 undertaken on the rosette disease of the Potato attributed to the sterile 

 fungus Bhizoctonia. It has disclosed that the prevalence of the disease 

 may be regarded as universal in the State. Experiments during the 

 season of 1903 show that treatment of the seed tubers with formalin and 

 sodium sulphide, by an immersion of two hours before planting, has 

 yielded profitable returns. This has been secured in soil previously 

 infected by the fungus of the disease, but has been found nearly twice as 

 great when applied to seed tubers planted in soil free from disease. The 

 treatment has had the effect of increasing the average size of the tubers 

 harvested. 



It is recommended that seed Potatos be treated before planting by 

 immersion for two hours in a solution of formalin containing one pound 

 of formalin in thirty gallons of water, since this is an efficient means of 

 rosette prevention and is easily applied. 



