LATE-BLIGHT AND ROT. 19 



gists conferred with regards it as a parasite of importance on either. 

 Professor Marchal, of Genibloux, said, however, that he sometimes 

 found a basidiomj'cetous fungus, Ili/jyoc/mis solaniFriW., ^ causing a 

 bhickleg-like stem disease in Belgium. Prof. T. Johnson, of Dul)lin, 

 sent specimens of Sclerotinia sclerotioruni^ which at times causes a 

 destructive stem disease in Ireland, called "yellow blight." He also 

 reports* the occurrence in Ireland of bacterial stem diseases, including 

 what he believes to be the malad}^ termed brown-rot in America and 

 shown by Dr. Erwin F. Smith to be caused by Bacillus solanacearwm . 

 In none of these cases was anything learned as to relative varietal 

 resistance to the disease in question. 



LATE-BLIGHT AND ROT DUE TO PHYTOPHTHORA INFESTANS. 



Late-blight and rot due to PhytopJdhora infestans occurs in Europe 

 even more widely and destructively than in America, being recog- 

 nized as the most important malady in all the countries visited by 

 the writer — Italy, Austria, Germany, Holland, Belgium, France, and 

 the British Islands. There was less unanimity of opinion than was 

 anticipated as to the probable life history of the fungus, and conse- 

 quently as to the remedial treatment. While all agreed that it lives 

 over in the seed tubers, the opinion was frequentl}^ expressed, by 

 scientific and practical men alike, that there is probably some hiberna- 

 tion in the soil, either in tubers left in the lield or in the haulms. 

 Possible hibernation in the tubers is to be associated with the fact that 

 potato tubers left in the soil are not killed b}^ frost in southern Eng- 

 land and the south of Europe. The value of Bordeaux mixture as a 

 remedy is recog'uized generally. Spra3'ing is consistently advocated 

 and practiced in the British Islands — especially Scotland and Ireland — 

 the Netherlands, Italy, and portions of France. Germany has been 

 surprisingly backward in accepting- or even fairly testing this remedy. 

 The reason seems to l)e that some of the experiments conducted by 

 scientific men have shown injur}' to the plants, and so they have pro- 

 nounced against it. No other remedial treatments are in common use. 

 *No one indorsed or practiced any method of seed disinfection. No 

 particular culture methods were advocated or condemned other than 

 attention to fertilization. There was a general agreement that 

 excessive use of nitrogenous fertilizers, either chemicals or composted 

 manures, increases the loss from this disease. Much attention is being 

 given, however, to the' relation of varieties and of source of seed to 

 disease resistance, and the results are of sufficient importance to merit 

 the somewhat detailed report which follows. 



^'Probably identical with Corticiuni vagum var. solani Burt, which is the fruiting 

 6tao;e of the common Rhizoctonia of the potato. 



''Johnson, T., Diseases of the Potato and Other Plants in Ireland, Journal, Dept. 

 Agric. Ireland, III, No. 1 (1902) 



