8 ‘* ROUGH-BARK ’’ DISEASE OF YELLOW NEWTOWN APPLE. 
In the case of trees growing in poor soil or impoverished from 
other causes the disease may be quite destructive, entirely killing 
large limbs and adding to the pale, sickly appearance of the already 
unhealthy foliage. In most cases, however, only an occasional 
branch is killed and the tree lives on with its branches showing 
many roughened areas, its vitality doubtless somewhat weakened 
but without serious injury as long as it is in good growing condition. 
The chief complete destruction seems to be to the smaller branches, 
as the larger limbs and the trunk, though usually injured locally and 
badly roughened, are seldom deeply girdled. 
So far as is known to the writer, the Yellow Newtown i is the only 
apple variety susceptible to the (home. At least, it is the only 
variety growing in Virginia which is very seriously affected: 
CAUSE OF THE DISEASE. 
ISOLATION OF THE FUNGUS. 
Cultures were made from diseased areas by Mr. W. M. Scott in 1907, 
and a fungus was isolated. In 1909 the same fungus was isolated by 
the writer from diseased spots whieh had only begun to develop. At 
various times since then the fungus, a species of Phomopsis, has been 
isolated from diseased branches and leaves of the Yellow Newtown 
and from the leaves of the York, Winesap, and other varieties of apples 
growing in Virginia. 
INOCULATION EXPERIMENTS. 
In the spring of 1910 imoculation experiments were made, using 
l-year-old and 2-year-old wood of the Yellow Newtown apple. 
Spores from pure cultures of the fungus growing on corn meal were 
inserted beneath the bark through tiny slits. Only sterile instru- 
ments were used, and care was taken not to make ragged wounds. In 
order to close up the slits at once the branches thus inoculated were 
immediately bound round with raffia, which was removed one week 
later. Within a month there appeared about most of the points of 
inoculation darkened areas, which became larger and more nearly 
black as the season progressed. These places at the end of the 
season resembled very closely the dark, sunken areas which are typical 
of the initial stages of the disease. In nearly every case the inner 
bark was black and dead and the diseased area was quite definitely 
marked off from the surrounding sound tissues. An examination of 
these branches, which was made in July the following season, showed 
in and about 18 of the 24 points of inoculation the sunken. rough- 
ened or cankered areas which are typical of the ‘‘rough-bark’”’ disease. 
Plate IT, figure 2, shows the disease as produced by artificial inocu- 
lations. All show the black, sunken areas which have begun to 
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