63 



III discu.ssii]}^ the ]»(»ssiliilii ics pro and con oT coiilrolliii;^ tluj 

 disease on individual trees after it lias become established, there 

 are many factors thai slunild he ( leari.v understood and carefully 

 consideied. It should be determined just what bearing each 

 will have on the main problem, just how each unfavorable one 

 can be overcome or at least neutralized, just how each favorable 

 one can be made even more helpful in the tight; all these, and 

 more, if ^^e are to enter the combat fully equipped. From 

 numerous points of view it is extremely unfortunate that the 

 disease has spread with such rapidity from its first known 

 centre, that nearly every person who has been detailed by the 

 States or the Federal Government to work on the disease has, 

 of necessity, been obliged to devote most of his energies to lo- 

 cating or destroying infected trees, and relatively little or none 

 to the research or investigation phase of the problem. 



Everybody who has had much to do with the disease will 

 agree with me, I am sure, when I say that in our efforts to con- 

 trol it we have been enormously handicapped by lack of just 

 such knowledge as conies only from systematic and painstaking 

 research. If we had this knowledge at the present time we 

 would undoubtedly see with clearness many things which are 

 now shrouded in the mistiness of uncertainty or in the darkness 

 of complete ignorance. Who, I wonder would venture to foretell 

 the elTects upon the whole question of control if we had spread 

 before us a complete, or fairly complete, positive knowledge of 

 I he many ini]K)rtant points connected with the disease, about 

 which we now know so little; e. g., to mention a few of these, its 

 origin, methods of dissemination, detailed effects upon the host, 

 ijumediate cause of the death or the lost vitality of the spores, 

 resistance of spores and mycelium to toxic agents, climatic in- 

 fluence upon host and disease, the extent to which it is possible 

 artificially to introduce various fluids into the circulatory sys- 

 tem of a tree without killing it, the extent to which insects are 

 responsible for the spread of the spores, the precise knowlege of 

 the relation of birds, rodents, wind, etc., to dissemination of the 

 spores. 



In attempting to control the disease on individual trees, there 

 are certain facts, as I have already stated, which have been re- 



