February, '19] SANDERS: EUROPEAN SCALE COMMON 91 



Pennsylvania. Fortunately, it does not occur in close proximity to 

 our larger fruit tree nurseries, hence has not become a nursery pest 

 problem. 



Records of Lecanium prunastri are at hand from the United States 

 Bureau, which indicate its having been collected by F. N. Meyer in 

 1907, at several points in China, and also in Chili Province, China, 

 in December, 1916. It was interesting to note that on a sample of 

 plum from Dougsi, China, it was associated with Diaspis pentagona, 

 the later species having also been found on various hosts quite com- 

 monly at several points in China. The writer can furnish a limited 

 number of specimens of this scale to those desiring them, and will also 

 gladly identify any material which is under suspicion as this species. 



Mr. T. B. Symons: I would like to ask if there is any attempt being 

 made to grow different varieties in infested areas for immunity tests, as 

 I understand that is the means of combating this disease in England. 



Mr. J. G. Sanders: As I understand, they now have two or three 

 varieties in England which are absolutely immune. It has been deter- 

 mined in conducting our laboratory experiments up there next year to 

 test out all well-known varieties of potatoes we have in this country 

 with a view to determining resistance and immunitj'. In the areas now 

 infected we will absolutely prohibit the growing of potatoes with the 

 idea of extermination of the disease. 



I might say another word here, that the potatoes, after assuming that 

 entire warty condition, quickly decay in the soil so that it impedes in- 

 spection work considerably if one is not on the ground at the proper 

 time. 



Vice-President E. C. Cotton: That would mean then the inspec- 

 tion would have to be made within three weeks after blooming. 



Mr. J. G. Sanders: From that time on until digging is done. Our 

 idea is to permit the growing of potatoes onlj^ by license; we shall have 

 men on the ground to control it in that way. 



Mr. C. H. Hadley, Jr.: Do you find that disease is transmitted 

 through storage? 



Mr. J. G. Sanders: There are many points that I might mention 

 about this disease that I could not bring out on account of lack of time. 

 Potatoes affected by this disease cannot be held in storage, because they 

 will quickly decay. 



Vice-President E. C. Cotton : The spores from the decaying warts 

 might attach themselves to sound potatoes and be a source of infection 

 of soil in the field. 



Mr. J. G. Sanders: Yes, and it would also be dangerous to trans- 

 port the potatoes. 



