Journal of Agricultural Research voi. xxvti, no. n 
840 
The cultures from the fungus on rose were indistinguishable from those 
of the cane blight fungus and the pycnospores were also in agreement with 
those of Botryosphaeria ribis. Therefore it seemed very likely that we 
were again dealing with the currant blight fungus on another unrelated 
host. Moreover, on the rose the fungus was apparently parasitic. Ac¬ 
cordingly, it was planned to conduct inoculation experiments with roses 
as well as currants. 
The inoculation experiments on currant were conducted as described 
above for the material from horse-chestnut, except that 2-year-old cur¬ 
rant bushes were used, and no parallel inoculations were made with the 
fungus from currant. Cultures made from a single pycnospore were used. 
More than half the twigs inoculated with the rose fungus developed typical 
cane blight and reisolations showed the presence of the chromogenic 
fungus in every case. The controls remained healthy. 
PARASITISM OF CURRANT CANE BLIGHT FUNGUS ON ROSE 
For the inoculations on the rose, 12 potted plants of the variety Colum¬ 
bia (Hybrid Tea) which had been propagated from cuttings were used. 
On April 2, 1923, 4 of the plants were inoculated with subcultures from 
those used in the currant inoculations, 4 with cultures made from the 
specimens collected in March, while the remaining 4 plants were kept for 
controls. The method of making the inoculations was the same as for 
currant. About two weeks after the inoculations were made all of the 
inoculated plants showed infection and the imperfect stage of the Botryo¬ 
sphaeria was fruiting on some of the stems. A week later the foliage 
above the point of inoculation had become yellowish green and was be¬ 
ginning to wilt, and by the last of the month it was dead and dry (PI. 2). 
The controls remained healthy and the wounds which had been made 
in the stems by the sterile scalpel had healed. The perfect stage of the 
Botryosphaeria was observed on a number of the infected plants two 
months after the plants were inoculated. Cultures made from the asco- 
spores, as well as the earlier reisolations from infected stems, were chro¬ 
mogenic and produced the imperfect stage of the fungus in about three 
weeks. Thus the pathogenicity of the fungus on the rose was established. 
When the rose garden was again visited late in June a number of plants, 
including the three on which the cankers were present in March, were 
found to be severely infected. Many canes 6 or 7 feet in height were 
killed to the ground, the brown, withered foliage being still attached. 
The pycnidial pustules of the Botryosphaeria were fruiting abundantly 
on these blighted stems and on one of the specimens brought to the labor¬ 
atory immature perithecia were present. 
On October 25 another survey of the garden was made and the disease 
was observed on still other varieties. The perfect stage of the fungus 
was fruiting abundantly on many of the specimens taken at this time 
and single ascospore isolations developed the typical chromogen. On this 
date the Botryosphaeria was collected for the first time on an American 
species, Rosa pratincola. Otherwise the disease has been observed only on 
rose species from China or their hybrids, as follows: R. adenosephala , R. 
banksiopsis X , R. bella X , R. bella X moyesii f R. caudata , R. heritierana, R. 
moyesii , R. moyesii X canina , R. multabracteata X , R. setipoda, and a num¬ 
ber of other varieties. There is nothing to indicate, however, that the 
fungus itself was imported from China. Cane blight occurs commonly on 
