LIST OF SPECIFIC DISEASES OF PLANTS 413 



in full in the remainder of part III. As it will be impossible to describe 

 in detail all of the diseases of the list, a selected number will be chosen, 

 which will illustrate the subject and which, if mastered by the student, 

 will lay the foundation for a more thorough acquaintance with the 

 diseases, which are prevalent in the United States, and which the 

 student, the teacher, the horticulturist, the forester, the agriculturist, 

 and the practical mycologist are likely to meet in their plant-growing 

 experience. It is recommended that for each of the diseases described 

 in the following pages the outline for the use of students given in 

 Lesson 29 be used to facilitate an investigation of the disease in the 

 laboratory, greenhouse, or in the open field. This is a method of 

 study approved by the best teachers of the United States. ^ The author 

 wishes to state emphatically that he has designedly kept down the 

 number of diseases described in the following pages because the 

 thorough mastery of a limited number is better than a superficial study 

 of a larger list. 



The general list precedes the descriptive pages of part III dealing 

 with a series of specific plant diseases, especially chosen because of the 

 author's familiarity with them, or because, they stand out prominently 

 as some of the more important diseases, which concern the American 

 plant-grower. 



These specific diseases are divided into two groups. One group 

 includes the parasitic diseases due to fungi as the causal organisms. The 

 other group includes the non-parasitic, or so-called physiologic diseases 

 of plants. These have been treated in general in part II of this book, 

 but certain of the non-parasitic diseases have become of such general 

 interest that they merit a more detailed treatment. The literature of 

 these diseases is very much scattered, the only general account being 

 one published by Sorauer, Lindau and Reh in their "Handbuch der 

 Pflanzenkrankheiten" (3d Edition of Sorauer), 1908. This work is be- 

 ing translated by Frances Dorrance. Four parts of Vol. I have been 

 printed and the other parts will appear as fast as translated and printed. 

 The English edition beginning 1914 is entitled "Manual of Plant Dis- 

 eases." To this work the student of plant pathology is referred for 

 many details. 



1 Whetzel, H. H. and Collaborators: Laboratory Exercises in Plant 

 Pathology, Ithaca, N. Y., 1916. 



