594 
Journal of Agricultural Research 
Vol. XXVIII, No. 6 
they grow Mature stromata of B. ribis chromogena have been observed on a 
single currant bush varying in size from 1 X 2-3 mm. on the smaller branches 
(Plate 1, C) to 3-3.5 X 5-8 mm. near the base of the older canes (Plate 1, 
D). As yet, the writers are unable to distinguish morphologically between 
the two forms of this species. 
The most important contribution to our knowledge of Botryosphaeria ribis 
since that of Grossenbacher and Duggar has just been published (13). This is 
the proof that the parasitic variety which causes cane blight of currants, occurs 
in nature on at least two other hosts, horsechestnut (Aesculus hypocastanum) 
and several cultivated varieties of rose (Rosa sp.). Moreover, on rose this 
fungus is undoubtedly parasitic. 
In view of the facts now in hand the writers are unable to escape the con¬ 
clusion that the fungus found by Putterill on apple in South Africa is identical 
with B . ribis chromogena even though this fungus has not yet been reported on 
apple from the United States. Putterill himself points out the close resemblance 
of this fungus to that described by Grossenbacher and Duggar. In size and 
arrangement of perithecia and pycnidia his fungus agrees closely with theirs; 
the ascospores he finds to be 19.2-19.5 X 6.5-8 p, and the pycnospores 32.4 X 
4.8 p, which are well within the limits of B . ribis. (See Table I and figures 
1 , 2, and 3.) Moreover, (6 } p. 264) his fungus possessed the chromogenesis 
which is characteristic of the parasite on currant. 
Table I .—Ascospores arranged by classes according to length in microns 
Total 
Class (in microns) 
number 
of spores 
13 
14 
15 
16 
17 
18 
19 
20 
21 
22 
23 
24 
25 
26 
27 
28 
29 
30 
31 
32 
33 
34 
35 
36 
37 
38 
39 
40 
Number of spores of 
Botryosphaeria ribis 
chromogena on currant 
in each class.. 
226 
5 
7 
9 
25 
35 
27 
21 
24 
19 
22 
16 
6 
3 
3 
4 
* 
Number of spores of 
Botryosphaeria ribis on 
apple in each class- 
207 
1 
5 
13 
8 
22 
22 
14 
25 
19 
21 
33 
16 
3 
2 
2 
1 
Number of spores of 
Physalospora malorum 
on apple in each class.. 
223 
- 
- 
1 
1 
5 
8 
4 
11 
10 
16 
11 
31 
20 
28 
24 
30 
11 
6 
3 
2 
-- 
1 
Ascospores arranged by class according to width in microns 
Total 
number 
of spores 
Class (in microns) 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
Botryosphaeria ribis chromogena on currant 
226 
.... 
8 
44 
91 
70 
11 
2 
Botryosphaeria ribis on apple... 
207 
11 
54 
94 
37 
10 
Physalospora malorum on apple. 
223 
25 
31 
46 
68 
26 
23 
3 
1 
—- 
Ascospores arranged by class according to ratios of length to width in microns 
Total 
number 
of spores 
Class 
1.5 
2 
2.5 
3 
3.5 
4 
4.5 
5 
Botryosphaeria ribis chromogena on currant._ 
226 
10 
50 
78 
56 
22 
8 
2 
Botryosphaeria ribis on apple. 
207 
1 
17 
74 
78 
26 
7 
2 
2 
Physalospora malorum on apple.... 
223 
6 
46 
77 
58 
21 
11 
4 
