Department of Plant Pathology xxxvii 



for publication. Work on the morbid anatomy and histology is nearing 

 completion. 



Aside from the work on bean mosaic, much energy has been devoted 

 to a solution of the problem of the etiology of mosaic diseases generally, 

 of which there are a large ntmiber. No important discoveries have been 

 made. Included here are peach yellows, cuciimber mosaic, potato mosaic, 

 and the mosaic diseases of a large nimiber of other plants. 



Various vegetable diseases have been studied in cooperation with 

 Rochester University and with the vegetable growers of Williamson. 

 The former work has been discontinued temporarily by the withdrawal 

 of Professor Jagger to engage in special work for the United States Depart- 

 ment of Agriculture. 



Work on the crown canker of roses has been continued. Experiments 

 for the control of rose mildew and black spot have been very successful. 



A number of little-known diseases of cereals and forage grasses are 

 receiving attention. Excellent progress has been made on two of these. 

 Experiments looking to better methods of control of some of the important 

 diseases of cereals are under way. 



Experiments are under way to determine the relation of the health 

 of plants to their susceptibility to disease. Other experiments are in 

 progress, under controlled conditions, to determine under what circum- 

 stances fungous parasites gain entrance to their host. The effects of 

 various sets of conditions on the development and progress of diseases 

 is also being studied. 



A number of mycological problems are being studied. The most 

 notable of these is a taxonomic study of the genus Botrytis and of the 

 family Coryneliaceae. The life history of a parasitic Eocronartium has 

 been completed. 



Extension. — The extension work of the Department can be classified 

 into two groups as regards source of funds — the regular extension work 

 conducted under the Smith-Lever project, and the emergency work 

 conducted for the New York State Food Supply Commission during the 

 period from May i to September 30, 191 7. Aside from correspondence 

 regarding various diseases and their control, work under one or the other 

 or both classes has been directed toward carrying out the following projects : 

 control of potato diseases; control of fruit diseases; control of cereal 

 smuts; control of diseases of other crops; plant-disease survey; exhibits; 

 extension schools and farmers' institutes. The work on these disease 

 control projects has been conducted largely by demonstrations on the 

 farm or in demonstration cars; by lectures at various meetings of farmers; 

 by farm visits; by the employment of field assistants in disease and insect- 

 pest control, who were located in the county for the special purpose 



