288 SUMMARY OF CURRENT RESEARCHES RELATING TO 



produces a " Blossom Wilt and Canker Disease " of apple-trees, the other 

 causes infection of the apple inflorescence, but only on the flowers 

 inoculated. A. L. S. 



Account of some Field Observations on the Development of 

 Potato Blight.— F. T. Brooks {Neiv Phytologist, 1919, 18, 187-200.) 

 Observations were made by the writers and others at Penzance and in 

 the Isle of AVight on the overwintering and new infection areas of disease 

 due to Phytopthora infestcms. They found that the earliest outbreaks of 

 blight developing in sitn are of strictly limited extent, and that from 

 them the fungus spreads centrifugally under favourable conditions until 

 the spores are widely distributed in the air and the disease becomes 

 epidemic. They found that tubers were early affected, but not from the 

 main stem or from the stolons. Infection from the soil or from infected 

 shoots seems probable, and possibly from resting oospores (proved to exist 

 by culture experiment). Critical evidence of such infection would be 

 difficult to find and thus to establish the method by which the disease is 

 carried on from year to year. A. L. S. 



Studies in the Physiology of Parasitism. V. Infection by Colleto- 

 trichum Lindemuthianum.— P. K. Dey (A7m. Bot., 1919, 33, 305-12, 

 1 pi.). The object of the investigation was to follow the stages of 

 infection of the bean by the above fungus. The author found that the 

 spore, when germinating on the host plant, produces a germ-tube which 

 develops at its end a thick-walled, dark-coloured appressorium directly 

 it comes into contact with the host surface, to which it is attached by a 

 mucilaginous envelope. From the appressorium a peg-like hypha grows 

 out which ruptures' mechanically the host cuticle and brings about a 

 swelling of the subcuticular layers. Only one instance was noted of the 

 germ hypha entering by a stoma. The action of the parasite on the 

 host cells is described. A. Ij. S. 



Disease of Red Clover. — The disease due to Macrosporlum saninse- 

 forme was first recorded by Cavara in 1890. It has now been thoroughly 

 investigated by J. Krakover {Nineteenth Report, Mich. Acad. Sci., 1917. 

 273-323, 5 pis.). The fungus attacks both leaves and petioles ; the 

 morphology of the fungus does not entirely agree with Cavara's descrip- 

 tion, but the name has been provisionally retained. The course of the 

 disease is described and the results of inoculation experiments. The 

 fungus enters usually between the epidermal cells of the host-leaf : 

 germinating seeds are readily attacked. The fungus was also cultured 

 on various nutritive media, and the results are given in full detail. The 

 author decides that the ultimate method of controlhng this and other 

 clover diseases must be the breeding of resistant varieties. A bibliography 

 of the literature cited is published. A. L. S. 



Fusarium Wilt of Potato in the Hudson River Valley, New 

 York. — The disease made itself specially manifest in 1914, and exhibited 

 the characters described as being due to Fusarium oxysporum. Royal. 

 J. Haskell {PhytopcUholoyy, 1919, 9, 223-60, 3 pis.), has investigated. 



