DEPARTMENT OF BACTERIOLOGY. 135 



DEPARTMENT OF BACTERIOLOGY, 



During the past year this department has been engaged in 

 the work of studying the fungous diseases of plants and their 

 treatment. The especial diseases under consideration have 

 been the peach leaf-curl ; the diseases of the apple — scab, 

 sooty spot, brown spot, leaf spot, and canker, also the various 

 rots affecting the mature fruit ; downy mildew of cucumbers 

 and melons. 



The most notable fact in regard to fungous diseases during 

 the past season was the serious outbreak of apple-scab. Dur- 

 ing the past ten years, the scab, while affecting certain sus- 

 ceptible varieties more or less, has not caused very serious 

 damage. Since about 1S95, in the vicinity of Durham it has 

 been rather difficult to find Baldwin, Greening or Northern 

 Spy apples sufficiently affected with the scab to serve as good 

 illustrations of the disease; but during the summer of 1902, 

 the scab became unusually abundant and did a large amount 

 of damao-e, attacking: manv varieties which usuallv suffer 

 little, among them the standard varieties mentioned above. 

 The outbreak seems to have been widespread. As to the 

 cause, the prevailing weather conditions would appear to be 

 the most probable one. The most striking feature of the 

 weather was the unusually low temperature which prevailed, 

 while the rainfall was abundant but hardly to be considered 

 excessive. 



It is difficult to estimate the amount of loss caused by this 

 outbreak but it would seem safe to set it at from one fourth 

 to one half of the crop. Our experiments on the Baldwin 

 demonstrated the efficiency of the Bordeaux mixture in the 

 prevention of the disease. The scab attacks the foliage of the 

 apple as well as the fruit, but a proportionate increase on the 

 leaves last season was not observable. 



