4 BULLETIN 1434, U. S. DEPARTMENT OF AGRICULTURE 
and sometimes distorted in shape. The hypertrophied zone may 
extend several centimeters along the stem, but the latter often con- 
tinues its normal growth beyond the lesion. The disappearance of 
red stem lesions later in the season, consistently followed by the ap- 
pearance of black stem spot in the same vines, leads to the belief 
that the fungus causing the latter disease often invades the red spots 
and produces its fruiting bodies in the same lesions. Much more 
frequently the black-spot fungus gains entrance through the red spots 
on the leaves and proceeds to attack the stem, through the petiole, 
without the appearance of any symptoms of reddening and swelling 
associated with Exobasidium In this case the stem lesions are black 
from the beginning, and immature perithecia appear early. The in- 
fected leaves are entirely killed, shrivel rapidly, and drop off easily, 
a result that Exobasidium apparently does not cause when acting 
alone. The minute immature perithecia are frequently borne on the 
petioles of infected leaves and have occasionally been found on leaves. 
Ascospores are produced the following spring. 
The latter type of infection is the rule in severe attacks of the dis- 
ease. The first indication is always an epidemic of red leaf spot. 
If weather conditions continue favorable for any length of time the 
leaves are completely killed by the invasion of the black-spot organ- 
ism and turn brown in a manner similar to severe hreworm injury. 
Close observation at this time will show numerous black stem lesions, 
usually centering around leaf scars, on both runners and uprights. 
The lesions generally encircle the stem entirely, though they may be 
confined to the side on which infection occurred. In severe cases 
most of the uprights may be killed by the black-spot fungus. 
Control. — Ked leaf spot and black stem spot are very dependent 
upon weather conditions. The disease may appear during a period 
of rainy or misty and cloudy weather at any time after vine growth 
has started. It is more severe in shaded portions of a bog and in 
sheltered places where air drainage is poor. The disease is rarely 
severe in large plantings of producing vines and consequently rarely 
warrants control measures other than cutting back the surrounding 
brush and trees to give better air drainage and light. That it may be 
controlled by Bordeaux mixture was demonstrated on the Fieselman 
bog, at Columbia Beach, Greg., in 1923. A portion of this bog was 
so severely attacked late in July that all the uprights were killed. 
Beginning about the 1st of August, several applications of 3-3-50 
Bordeaux mixture were made at frequent intervals. New uprights 
which grew from below the old dead ones were kept free from the 
disease and matured normal fruit buds the same season. 
ROSE-BLOOM 
Rose-bloom, caused by Exobasidium oxy cocci Host., is occasionally 
found in Washington and Oregon. Shear (6, 8) has noted that this 
fungus is erratic in making its appearance in all the regions where it 
occurs. The disease was fairly prevalent in 1922, but could scarcely 
be found in any of the other three years of these observations. 
It apparently causes no appreciable injury in this section, since the 
bog most severely affected in 1922 yielded a crop of berries larger 
than the average of producing bogs that year, and the crop was also 
good the following year. The disease appears soon after the vines start 
