Introduction xxix 



It was the writer's intention to avoid technical 

 terms as far as possible. However, it was found ex- 

 tremely difficult to omit every trace of a technical 

 vocabulary, inasmuch as the popular terms are not 

 always adequate in identifying a disease or in de- 

 scribing its causal organism. As far as was consistent 

 all popular names were accepted and retained in this 

 work. However, there are many diseases which 

 have as yet no popular names. As an illustration 

 may be mentioned certain spot diseases of particular 

 hosts. These spots may be caused by different fungi 

 and yet resemble each other. In such a case how are 

 we to name these diseases? The surest way to avoid 

 confusion is to call the diseases by the name of the 

 causal organism, such as Phyllosticta leaf spot, Cer- 

 cospora leaf spot, etc. Professor Stevens has sug- 

 gested that we name all diseases by the name of their 

 causal organism and add to it the term "ose, " such 

 as Phyllostictose, Cercosporose, Sclerotinose, etc. 

 The writer has not adopted Stevens terminology. 

 In many cases the popular name of a disease de- 

 scribes it far better than a technical term can do. To 

 drop altogether such valuable popular terminology 

 would only confuse the practical man. For instance, 

 the popular term for lettuce "drop" is far more sug- 

 gestive than "Sclerotinose." 



From a practical consideration, the healthy plant 

 is of greater importance than the disease. If we were 

 to bend all our energy and skill to safeguarding the 

 health of our crops, we would not be pestered with 

 diseases. This is the point of view of this work. 



