632 STATE BOARD OF AGRICULTURE. 



THE LEAF SPOT DISEASE OF TOMATO. 



Technical Bulletin No. 25. 



FOREWORD. 



The importance of the tomato crop in the state of Michigan and the 

 seriousness of some of the losses occasioned by diseases led the Depart- 

 ment of Botany to begin investigations on the subject several years ago. 

 The investigation of one of these diseases, the leaf-spot, the subject of 

 this bulletin, was turned over to one of the advanced students, Mr. Ezra 

 Levin, who began work in the fall of 1913 and devoted a very large part 

 of the following school year and summer to the problem. The work was 

 carried out along lines laid down by Dr. G. H. Coons, Eesearch Assist- 

 ant in Plant Pathology, who kept very close supervision of Mr. Levin's 

 work. The revision of the manuscript and the larger part of the prep- 

 aration of the Bibliography were also carried out by Dr. Coons. The 

 result of the investigations throw great light upon the structure and life 

 history of the fungus {Septoriu lycopersici) causing the disease and ex- 

 plain many of the apparently contradictory observations and conclu- 

 sions of previous investigators. They are of especial value as they show 

 where lie the vulnerable points in the life history of the fungus, an item 

 of the utmost importance in the combating of a disease. Furthermore, 

 the facts learned have been found to shed light upon other diseases 

 caused by other species of Septoria, such as the late blight of celery, etc. 



In view of the foregoing it is believed that it is highly desirable to 

 publish the details of the investigations as a Technical Bulletin, for the 

 benefit of investigators wherever the diseases of this type are being stud 

 ied, and to present the main facts, together with directions for control, 

 in a popular form in another publication. 



ERNST A. BESSEY, 



Botanist. 



