8 THE CONTROL OF APPLE BITTER-ROT. 



find as much as 50 per cent of the fruit of this variety harvested in 

 good condition was exceptional. The Yellow Newtown growlers of this 

 section had had a similar experience with the crops of I'JOl and 1899 

 (two and four years previous), and some were on the point of abandon- 

 ing their orchards in despair, one man going so far as to cut down his 

 trees. It seemed, therefore, especially desirable for the Bureau to 

 determine the best methods for combating this disease and to obtain 

 data upon which definite recommendations could be based. Accord- 

 ingly a series of experiments was planned, which were carried out in 

 the orchards of Mr. W. H. (loodwin. at Avon, Va., to whom the 

 Department is nnich indebted for valuable sei'vices in facilitating the 

 work. The work was outlined and some spraying done in the spring 

 of 1904, but this being the "off year" it soon developed that there 

 would be no crop of apples in that section, and the actual work reported 

 upon in this paper was not commenced until the spring of 1905. 



THE DISEASE AND ITS CAUSE. 



A detailed account of the disease and the fungus causing it having 

 appeared in a previous bulletin of this Bureau," many details will be 

 omitted in the following discussion, the attempt being made to include 

 only those facts with special bearing on the sul)iect of this paper. 



THE DISEASED SPOTS ON THE APPLE. 



The diseased spots are usually" a ([uarter to a half inch in diameter 

 before the fruit grower ordinaril}' notices them, but the}' first appear 

 as ver}^ small, yellowish-brown, sometimes water}' specks, frequently 

 bordered with a ring of purple-red. The purplish mai'gin is especially 

 prominent on spots that are retarded l>y cool weather, and many late 

 infections appear oidy as red or ])urplish specks, never developing 

 farther on account of adverse conditions. On the other hand, the 

 purplish coloration is likely to be entirely absent from a spot that is 

 developing rapidly under favorable conditions. As the spot enlarges 

 and grows older it becomes dark-brown in the center, shading off into 

 a light watery margin. It is circular in outline, with a well-defined 

 margin, and soon becomes sunken. (See PI. I, and PI. VI, fig. 1.) 



When the spots are about one-half inch in diameter, fruiting pus- 

 tules begin to appear in the form of small black dots slightly raised 

 and usually arranged in concentric rings (PI. VI, fig. 1). These pus- 

 tules soon break through the skin (PI. II, G), discharging pink, sticky 

 spore masses, which are readily washed off' by dews and rains. As 

 the disease progresses, other rings of pustules appear and give forth 

 spores in great alnindance. When the pink spore masses are washed 

 away the pustules appear as black ragged openings through the skin of 



« Von Schrenk and Spaulding, 1. c. 



