Bulletin 84. 
6 
shrivelling leaf-stems. The discolored outer bark blended gradu¬ 
ally into normal appearing tissue but the inner bark was dis¬ 
colored for some distance below any external evidence of disease. 
Unfortunately the infected orchard is so far from the Experi¬ 
ment Station that the progress of the disease could not be 
watched, but specimens of diseased ripe fruit were secured from 
Mr. Mathews on August 2. These were in all stages of decay. 
Those that were only slightly attacked had a small shrunken area 
over which the skin was discolored but little. In those specimens 
where a half or two-thirds of the fruit was involved the tissue was 
much shrunken and the skin over these areas was quite brown. 
In some specimens a thick juice, swarming with bacteria, oozed 
from the diseased tissue and collected in a large drop on the sur¬ 
face. Much watery appearing tissue which was still firm sur¬ 
rounded the diseased parts. 
Infection evidently took place more readily early in the sea¬ 
son as there was much more diseased fruit at the time of my visit 
than there was when the later specimens were secured. 
Since the appearance of Prof. Jones’ paper* in which he 
proves that pear blight may produce twig blight in various kinds 
of plum trees it seems probable that this 
blight and rot of the apricot was due to 
the same organism. The trees are situ¬ 
ated in a mixed orchard and the adjacent 
pear and apple trees suffered severely 
from an outbreak of pear blight during 
the season of 1902, and it was abundant, 
though not as severe, in 1903. Micro¬ 
scopical examination showed that the 
diseased parts of both twigs and fruit 
were swarming with bacteria and that 
these germs were abundant in the watery 
o J 
appearing though firm flesh of the fruits. 
Working upon this supposition ex- 
FiG; i. Apple three days after periiuents were undertaken as follows: 
inoculating with diseased tis- i. 
sue from an apricot fruit. June 30, 12 apples were inoculated by 
inserting under the skin bits of the watery tissue taken from dis¬ 
eased apricot fruits. These wounds were covered at once with 
sterile grafting wax. Four of the apples were picked by children 
but at the end of twelve davs the remaining- eight were found to 
have developed the rot that is peculiar to apples attacked by pear 
blight. The disease gradually spread until the entire apple was 
discolored and shrivelled and drops of sticky fluid appeared upon 
the surface of most of them. (Fig. 2.) 
*Jones, L. R. Studies Upon Plum Blight. Centralb. f. Parasitenk. u. 
Infek. II. Abt. II. Band. pp. 835-841. 
