30 THE BITTER ROT OF APPLES. 



in mummified condition on the trees, or lying on the ground under the 

 trees, probably served as infection centers in many instances; but in 

 many cases, although all mummies and diseased apples were carefully 

 removed during the winter, the disease reappeared in the orchard. 

 Another feature explained with difficulty until recently was the fact 

 that even with many specimens of bitter-rotted apples of the previous 

 season lying on the ground under the trees, the disease first manifested 

 itself in the tops of the trees and very rarely on the branches nearest 

 the ground. In other words, it was difficult to understand how the 

 spores of the bitter-rot fungus got on the fruits in the tree tops from 

 the mummies on the ground without first infecting those on the lower 

 branches. It had been noted repeatedly that the disease frequently 

 made its first appearance on the apple tree in a cone-shaped area, with 

 the apex of the cone near the top of the tree. It was this observation 

 oft repeated which led to the discovery during the past summer of 

 what is probably the winter stage of the bitter-rot fungus. 



On July 10, 1902, a Mr. R. H. Simpson discovered peculiar depres- 

 sions on many 1 >ranches of apple trees in his orchard at Parkersburg, 111. 

 Mr. Simpson was at that time employed as an agent of the Department 

 of Agriculture to conduct spraying experiments looking toward the 

 control of the bitter rot of apples by spraying with fungicides. Mr. 

 Simpson had been hunting for the source of the first infection, and 

 early in July he noted the peculiar cone-shaped distribution of the 

 fruit which showed the first signs of the bitter rot. On many trees 

 the grouping of the infected fruit in the cone shape was so marked 

 that it seemed probable that the disease had started near the apex of 

 the cone and had spread downward and outward. In nearly every 

 instance Mr. Simpson found blackened depressions of a characteristic 

 appearance on one or more branches at or near the apex of the cone of 

 infected fruit. These black depressions in the apple limbs occurred 

 so constantly associated with early bitter- rot infection that Mr. Simpson 

 proceeded at once to cutout all blackened areas which he could detect. 

 The blackened sunken areas in the apple limbs have the appearance of 

 " cankers," as this term is generally understood, and they have been 

 called cankers since their first discovery. Mr. Simpson was able to 

 locate the canker in more than 95 per cent of the cases by following 

 up the cone of infected fruit to the apex. 



On the day following Mr. Simpson's discovery at Parkersburg, 

 Professors Burrill and Blair, of the University of Illinois, visited the 

 orchard at Parkersburg and learned of Mr. Simpson's find. Believing 

 that the causal relation between the cankers and the bitter rot was 

 thereby established, they published a preliminary note in a circu- 

 lar of the Agricultural Experiment Station of Illinois, in which they 



«The discovery of the apple cankers was made July 10, 1902, in the afternoon, as 

 indicated by a telegram from Mr. Simpson to the writers on the same day, not July 11, 

 as stated in Circular No. 58 of the Illinois Agricultural Experiment Station, July, 1902. 



