INTRODUCTION 5 



lege or University in the United States 

 offers courses in Plant Pathology, the sup- 

 ply of trained investigators is neverthe- 

 less limited. Since every Experiment Sta- 

 tion is directly supported by state and 

 federal funds, it is natural that every 

 worker is more or less impelled to inves- 

 tigate diseases of plants which are of 

 greatest economic importance. For this 

 reason nearly all the research was directed 

 to fruit, cereal and forage crops. Flower 

 pathology is as yet in its embryonic stage. 

 To-day there are but few institutions of 

 learning which have established definite 

 divisions in the investigation of diseases 

 of ornamental plants. As stated in the 

 preface, the sweet pea diseases have 

 received scant attention, except those 

 worked by the writer. Even in this case 

 for lack of funds the investigations were 

 brought to an untimely end. The little 



