DISEASES OF VARIOUS CROPS I213 



for consumption, for this purpose. In addition, they are sown too close 

 in the potato fields, and the soil is insufficiently tilled and manured. They 

 grow a variety of mediocre quality, but which is somewhat resistant to di- 

 sease. 



A description is given of the enemies observed on the potato. Epilachna 

 territa largely destroys the foliage by gnawing it. Phytophthora injestans 

 has been found in some plantations lying at an altitude of 5500 to 6500 feet ; 

 the climatic conditions hardly appear favourable for a spread of this di- 

 sease in regions of a lesser altitude. Macrosporitmi solani causes a dry rot of 

 the foliage, and has been found at an altitude below 5500 feet. A root ftmgus, 

 the attacks of which are somewhat dangerous to other crops, sometimes as- 

 sails potatoes. A disease, the cause of which is still unknown and which is 

 shown by the leaves rolling up, is rather frequent in some newly imported 

 ^-arieties. Finally, considerable damage is caused by the disease known in 

 Germany as " Eisenfleckigkeit ". The diseased tubers do not differ ex- 

 ternally in any way from the healthy ones. On cutting them open, brown 

 spots are seen in the central tissues. These spots turn black when the po- 

 tatoes are cooked. It has not been possible to find any very definite cause 

 giving rise to this disease. Probably defects in the methods of cultiva- 

 tion, especialh- with the natives, very much influence its appearance, and 

 an improvement will be observable when the usual methods are replaced 

 by more rational ones. 



941 - Cronartium ribicola attacking Ribes, in Ontario. — Howin f. i:. and 



Mc CtJBBiN W. A., in Phytopathology, Vol. 6, No. 2, pp. 18^-183. Baltimore, Mil., 1916. 



In 1914 and 1915, in nine counties on the banks of the great (3ntario 

 lake, plantations of Rihes especially R. nigrum I^. were considerably damag- 

 ed by Cronartium ribicola Fisch. de Waldh. 



The following cultivated and wild species were attacked : R. nigrum, 

 L, ; R. vulgar c Lam. ; R. grossularia L- ; R- aureum Pursh ; R. tynosbati L.; 

 R. triste Ball. ; E. Jioridum ly'Her. ;.and R. prostratum I/Her. 



The aecidial form {Per icier mium) is found on Pinus strobus, both na- 

 tive and imported, in the countries of Brant, Durham, Halton, Welland, 

 Wellington and Went worth. 



In the spring, the infection spreads from the pine to the Ribes on which 

 the teleutospore develops. It is, however, not impossible, although the 

 experiments undertaken by the Writer yielded a negative result, that 

 the disease may winter on the leaves of Ribes itself. As regards the 

 susceptibility of the different species, R. nigrum is said to be the most 

 susceptible. On the other hand, R. rubrum is thought to be much less so 

 (the variety " London red " is entirly refractory) as also is R. grossularia. 



It should be noted that this disease, which may be said to have no eco- 

 nomic importance in Europe, may occasion extensive havoc in Ontario, 

 owing to almost complete defoliation. With regard to the means of control, 

 good results are obtained by api)lications of Bordeaux mixture or soluble 

 sulphides for fifteen days during the sununer. 



