178 NEBRASKA STATE HORTICULTURAL SOCIETY. 



National Apple Shippers Association estimated that bitter-rot 

 of apples cost the United States the enormous sum of $10,000,000 

 in 1900. The pathologist must carry his experiments farther, 

 and attempt to find remedies and preventive measures. Much 

 has been done in recent years in the vray of treatment of plant 

 diseases, but in the future this phase of work must be ap- 

 proached from a more scientific basis. Every century will not 

 witness the accidental discovery of a Bordeaux mixture or some 

 equally important treatment. Painstaking, accurate, scientific 

 experimentation must yield the results for which we are 

 looking. 



Spraying with various preparations has been an important 

 preventive measure, saving millions of dollars annually to the 

 fruit-grower of the country. For example, spraying saved 

 $12,700 in one peach orchard in California in one year on a single 

 variety, and I have no doubt that many of you have seen the 

 value of such treatment in your own experience as commercial 

 growers of fruit. There are many diseases for which such ex- 

 ternal application of poisons are of no avail, and other methods 

 must be resorted to. In many cases the remedies or preventive 

 measures recommended are too expensive or too laborious, to 

 appeal to the practical man and better and more practical ones 

 must be sought. 



Stimulated by the method of treating diseases in animals by 

 internal medicine, an occasional claim is made by some investi- 

 gator that certain plant diseases may be cured or prevented by 

 similar methods. It is safe to say that at present there is little 

 of promise along that line. 



' Just as civilization has produced races that are less hardy 

 than aborigines, so cultivation has, generally speaking, produced 

 less resistant races or varieties of plants. It is unfortunate that 

 our cultivated plants suffer more from disease than the worthless 

 weeds. But there are individual differences that may be noted 

 in any given species; some individuals are apparently more re- 

 sistant than others, also some varieties are more immune from 

 disease than others. If the hardy and resistant individuals and 

 varieties are selected and propagated, the production of more 

 resistant and even immune varieties may be accomplished. To 



