256 Early Studies in Bacterial Plant Diseases 



standpoint of physiological chemistry but the definition, for pur- 

 poses of experimental study, of the sources of such basic elements 

 as carbon, nitrogen, sulfur, etc., and the various possible processes 

 of change and combinations of elements resulting from synthe- 

 sizing activities of such organisms had important bearings in 

 laboratory work of pathology and to some extent in field studies. 



Early in 1893 Pierce agreed with Smith that they could not. 

 expect to " master all plant diseases the first time trying." He 

 wrote: 



I feel well satisfied if one-fourth or one-third of those undertaken by 

 myself are handled satisfactorily. I much regretted that the fermentation 

 of figs could not be prevented by the use of sprays. The experiments 

 conducted in that disease the past summer were laborious and extensive, 

 but with no marked results so far as prevention is concerned. It is evident 

 that insects take the yeast to the center of the ripening figs, and all the 

 sprays in Christendom applied to the exterior won't save a fig. I was 

 greatly disappointed when I found this out, but what can a man do about 

 it except catch the 177 sects or stop up the jigs? 



The souring ferment of figs was a disease of the internal parts 

 of the plant and, to this extent, similar to Smith's bacterial disease 

 of cucumber, cantaloupe, and squash. From his field research 

 Smith had soon learned that the wilting, the cucurbit disease's 

 most important symptom, was an internal phenomenon set up 

 after the germ had secured entrance, and this though the external 

 parts of affected stems appeared to remain uninjured. Quite 

 properly, therefore, he had not given his first attention to prophy- 

 lactic spraying remedies but studied the insects which possibly 

 transmitted the disease and examined the plant's physiology to 

 understand its pathology and the workings of the bacterium. 



The significance of a prescriptive remedy, measured in dollars 

 and cents to growers, was not always proportionate to the com- 

 plexity of the achievement. Years of discouraging effort some- 

 times were spent by pathologists to arrive at a simple remedy, 

 which, however, when found, proved of great economic value. 

 From Chico, California, on July 27, 1894, Pierce wrote to Smith 

 of his " largest and most complete experiment " he had thus far 

 undertaken — namely that of finding a fungicide by which to 

 control curl leaf of the peach: 



