DISEASE RESISTANCE AND VEGETATIVE VIGOR. 23 



of Mairsland, Auchtermuchty, Scotland, has originated some varieties 

 of liio-li repute; Sutton & Sons, of Reading-, England, have also taken a 

 prominent part in this work. Scotland-grown seed of all the leading 

 varieties can be secured from Thomas Scarlett, of Edinburgh, and Mr. 

 Scarlett has some promising varieties of his own introduction. Any- 

 one desiring more specific information should secure the publications 

 of the National Potato Societ}^ from its secretary, Walter P. Wright, 

 Postling Vicarage, Hythe, Kent, England. 



Meanwhile the German Potato Station has been making extensive 

 tests, doing some breeding and encouraging several potato breeders.'^ 

 These efforts have not been directed primaril^^ to disease resistance, 

 but the station has taken note of this feature and published the data 

 regarding all varieties tested. 



While the results of this work in Europe have been collected or 

 correlated bv no one, the writer was able to gather considerable infor- 

 mation, in addition to that already referred to, from conversation with 

 potato specialists, especially in Great Britain. This, together with 

 what has been learned in Amei'ica, is made the basis of the followino- 

 discussion. It is to be regretted that it is impracticable to give detailed 

 credit in some cases to those who kindl}^ furnished the information. 



THE MEANING OF DISEASE RESISTANCE. 



Although potato specialists, especially in England, apply the term 

 "disease proof " to their favorite varieties, this is not to be taken liter- 

 ally. No variety has as yet shown itself to be absolutely proof against 

 disease. The writer personally collected leaves infected with the 

 blight fungus from two varieties which were said to be "disease 

 proof." Absolute resistance against the blight fungus has not as yet 

 been and may never be secured. Varieties are known, however, which 

 show a relatively high degree of disease resistance. This mav be 

 shown in the delay in date of appearance of the blight on the leaves 

 or its slower progress after appearing, and still more clearl}^ in the 

 relatively small amount of loss from rot of the tubers. M'ost of the 

 exact observations made in Europe have been based on this latter 

 difference. 



DISEASE RESISTANCE AND VEGETATIVE VIGOR. 



Disease resistance and vegetative vigor are closely associated, 

 although the factors involved are not necessai'ily identical. In an}' 

 consideration of the problems of the life and death of the potato plant 

 it must be remembered that the potato has two natural methods of 



«The most active of these are Paulsen, Cimbal, Riohter, and Dolkowski. Graf 

 Arnim-Schlagenthin, of Nassenheide in Poinmern, is an extensive breeder and dealer 

 in new varieties, as is also F. Heine, of Hadmersleben. 



