PROBLEMS AND PROGRESS IN PLANT PATHOLOGY 
107 
diseases having clearly defined symptoms which follow a regular 
course, let him grow China asters for a series of years in his garden 
and trace the course of aster yellows. Here we have a malady as 
clearly characterized as a fungus rust or wilt disease; unknown, I 
believe, in Europe, but widespread in America, variable with season 
and locality, yet its etiology and pathology are entirely problematical. 
But these are not problems to be undertaken lightly. Considering 
their inherent difficulties we may be thankful that such critical and 
persistent work has been given to certain types already, notably to 
peach yellows by Smith and to the mosaic disease of tobacco by 
Mayer, Beijerinck, Woods and others. It is encouraging to see that 
earnest attention is being given to certain apple maladies in different 
sections, especially the so-called ''brown spot" or "bitter pit" in 
South Africa and Australia.^^ 
Our encouragement will be greater, however, when we see the clear 
recognition of the fact that training in parasitology has only indirect 
value when it comes to such problems. The most evident need if we 
are to advance in the fundamentals of our research in this field of 
plant pathology is the reinforcement of our ranks with young men 
equipped with a high degree of special training in plant physiology 
grounded in organic chemistry, and ready to dedicate rheir services 
long and patiently to these physiological researches. 
VIII. The Problems of Disease Control 
Now you are expecting the statistics showing how many millions 
America is adding to her income by modern methods in disease control ; 
but you have heard them often, so I need not repeat them; and they 
have much of truth in them. The yankee is practical, and the yankee 
mind dominates everywhere in America. Instead of boasting we 
rather owe ourselves this explanation — shall we say apology — when 
we point to the relative proportion of the space in American plant 
pathological publications given to the consideration of the spray 
pump and the disinfecting solution. How could it be otherwise? 
The millions spent by patent medicine advertisers have implanted 
firmly in the American mind the idea that each animal disease is a 
specific thing and for it there exists a specific remedy. It was, there- 
See Stone, G. E. and Smith, R. E. Mass. Agr. Exp. Sta. Bui. 79. 1902. 
McAlpine, D. Bitter pit investigations. First progress report. Melbourne. 
1911-12. 
