DISEASES OF PLANTS. 847 



which he was able to propagate the uretlo stage of rusts in the greenhouse for 

 several months. The species experimented upon were Puccinia dispcrsa and 

 P. coronifcra. These were carried through ::;7 generations of the uredo stage. 



P. coronifera was found not to self-propagate to any extent, even when 

 abundant host material was present and a constant humidity of 93 per cent 

 was maintained. This high humidity was found essential in securing inocula- 

 tions with uredospores of this species. The total exclusion of light either early 

 or late in the incubation period of the fungus affected its development and 

 resulted in an almost complete cessation of growth. The uredospores of 

 P. coronifera, when stored at room temperatures, were found to lose their 

 capacity for germination gradually, only 0.2 per cent germinating after a stor- 

 age of 84 days. 



A bibliography is appended. 



Report of 1908-1912 studies on celery diseases in Hamburg lowlands, 

 II. Klebaiix (Jdhrh. llnmhunj^ ^Vi^s. An.st., 30 {1012), Jicihcft .i, pp. 1-51, 

 pis. 2). — These investigations are said to have confirmed previous conclusions 

 (E. S. R., 22. p. 74('>) regarding the agency of Scptoria apii and Phoma api'ivtAa 

 in producing respectively leaf spot and scab of celery. It is claimed to have 

 been shown that seed often carry fruiting bodies of »S. apii, also that the spores 

 live through the winter on plant rubbish in large numbers. Scab is also said 

 TO be transmitted through the seed and plant waste, but very slightly by means 

 of air currents. 



Directions are given for the manufacture and employment of a number of 

 fungicides recommended. 



Diseases of the potato tuber and the selection of sound seed, R. W. Jack 

 {Rhodesia Agr. Jour., 11 {191J,), Xo. S, pp. 399-J{07, pis. ,5).— The author 

 briefly describes scab due to Oospora scabies, corky scab caused by Spongospora 

 feahics, Rhizoctonia stem rot, dry or white rot due to Fiisariuni solani. bac- 

 teriosis or wet rot due to BacUlus sol ana ce a rum, nematode disease, etc. 



For the prevention of these different diseases the choice of seed from unin- 

 fected regions is advised, and where suspected seed is obtained treating the 

 tubers with formalin or corrosive sublimate solutions is recommended. 



The perennial mycelium of Phytophthora infestans, I. E, Melhus {Centhl. 

 Bakt. [etc.], 2. Aht., S9 {1913), .A^o. 18-19, pp. 482-1^88, figs. 2).— It is claimed 

 to have been shown in the experiments here described that the mycelium of 

 P. infestans may spread from the tuber into the young shoots, developing in 

 the portions above ground and producing aerial spores which may become the 

 source of secondary infections. A detailed account of the author's experiments 

 is to be published in a later contribution. 



Spraying of potato crop, C. McDonald and R. McKenzie {Xorth of 8cot. 

 Col. Agr. Expt. Leaflet 29 {1913), pp. 118-122).— Jt is claimed, as the result 

 of an analysis of the figures obtained in 53 trials, that there was an average 

 increase on sprayed plats of 4,000 lbs. of sound tubers per acre, the quality also 

 showing improvement. A few cases in which there was little or no improvement 

 are explained by heavy rainfall just after spraying or by too great delay in its 

 employment. 



A disease of spinach, P. Passy {Jour. Soc. Nat. Ilort. France, Jf. ser., 15 

 {1914), Pel)., pp. 106, 107). — A brief account is given of a disease of spinach 

 which is thought to be of bacterial origin. The infected plants lose their green 

 color, turning yellow. Later the leaves become partially destroyed, the disease 

 beginning in the petiole, which is destroyed, and eventually the plant dies. 

 Preliminary investigations have shown that the trouble is confined to the aerial 

 parts of the plants, the roots retaining their normal appearance. 



