8 3 8 
Journal of Agricultural Research 
Vol. XXVII, No. II 
destructive also, especially during certain seasons, in the Hudson Valley 
of New York and in southern Connecticut. Farther north, however, it 
seems to be of much less importance, and has not yet been found to be 
serious in northern New England or in Canada. The fungus has not been 
found in Alaska, though currants are commonly grown there. 
No effective method of control for currant cane blight has been devel¬ 
oped. Systematic cutting out and burning of the diseased parts has, 
however, served to keep the disease down to a point where currants are 
commercially profitable even though the disease is commonly present. 
THE CAUSAL ORGANISM 
Grossenbacher and Duggar showed by inoculation experiments that 
currant cane blight was caused by a fungus to which they gave the name 
Botryosphaeria ribis . They also called attention to the frequent occur¬ 
rence on currant canes of a morphologically similar fungus which is not 
parasitic and which they designated as Botryosphaeria ribis forma 
achromogena . This form name was chosen because the saprophyte 
lacks the most conspicuous cultural character of the parasite, namely, the 
production on starch paste or other starchy media of a bright pink color 
during the first three or four days of growth. 
The observations of the senior writer as to the causal organism have 
fully confirmed those just reviewed. Currant cane blight seems to be 
everywhere associated with the chromogenic Botryosphaeria, and infec¬ 
tion with the chromogen is readily secured from inoculations made at the 
right time. 4 On the other hand, the results of inoculations with the non- 
chromogenic form have been uniformly negative. Grossenbacher and 
Duggar consider the two forms morphologically practically identical, the 
ascospores measuring 16-23/1 by 5-7/1 and the pycnospores 16-31/1 by 
4.5-8/* *. The material examined by the writers varies through somewhat 
wider limits than those given by Grossenbacher and Duggar, perhaps 
due to the fact that it has been derived from a wider geographical range. 
Comparison of our material, however, both with the authentic material 
distributed in Bartholomew’s Fungi Columbiani, Numbers 3408 and 3409, 
and with the original slides of Grossenbacher and Duggar now preserved at 
the Geneva Experiment Station, as well as culture and inoculation work, 
leaves no doubt that the fungus described by them is identical with that 
used in our inoculation work on currant. 
OCCURRENCE OF THE CURRANT CANE BLIGHT FUNGUS ON HORSE- 
CHESTNUT 
Our work on the currant cane blight fungus forms a part of the exten¬ 
sive studies of the fungi belonging to this group which have been carried 
on for more than 15 years by Shear and his associates. 5 During this 
period, as stated by Shear and Beckwith, 6 fungi which closely resembled 
Botryosphaeria ribis morphologically have been secured from several 
hosts. However, although one strain collected on Vibumu'm showed 
chromogenesis when cultured on starchy media, no direct evidence of the 
occurrence of the currant cane blight fungus on hosts other than Ribes 
sp. was secured until 1921. 
4 Grossenbacher, J. G., and Duggar, B. M. op. cit., p. 137. 
* Shear, C. B. life history op melanops quercuum (schw.) Rehm forma vms sacc. (Abstract.) 
Science 81 : 748. 1910. 
8 Shear, C. L., and Beckwith, A. M. life histories of melanops. (Abstract.) Phytopathology 6: 
109. 1916. 
