358 Journal of Agricultural Research voi. xv, no. e 



potatoes a miscellaneous lot of fungi was isolated, Mucor racemosus and 

 Mticor sp. predominating. The sweet potatoes were a long time in 

 storage at such a temperature, and, if not supported by other experi- 

 mental data, these results would have little value. Even then they 

 would hardly deserve to be included did it not form a link in the chain 

 of experiments conducted with this organism and several species of 

 Fusarium. All the controls in the above experiment were rotted, but 

 none with G. saubinetii. 



Experiment II. — On October 29, 1914, 40 sweet potatoes, after a thor- 

 ough washing, were divided into two equal lots. One lot was disinfected 

 for 30 minutes in a i to 200 solution of formaldehyde (40 per cent). The 

 two lots were inoculated by inserting spores and hyphae into a wound. 

 The potatoes were then immediately immersed in a suspension of the 

 spores in sterile water, after which they were wrapped in moistened 

 filtered paper and then in oiled paper and placed in cloth bags. The 

 two lots were stored near together in a sweet-potato storage house at 

 Arlington Experimental Earm, Virginia. These potatoes were removed 

 from storage March 11, 1915, and cultures made from those that were 

 partially or completely decayed. Sixty-seven per cent of the treated 

 lot remained sound; the others were from one-third to two-thirds 

 decayed. Gibberella saubinetii was isolated in pure culture from 85 

 per cent of those that were decayed. Fifty per cent of the untreated 

 lot (10 potatoes) remained sound and G. saubinetii was isolated from 

 90 per cent of those that were decayed. Thirty-five per cent of the 

 controls (20 sweet potatoes) rotted slightly, but G. saubinetii was not 

 isolated from any of these. 



Experiment III. — A third lot (21 sweet potatoes), disinfected as above 

 and wrapped but not immersed in a spore suspension, was stored in an 

 Irish potato storage house. The temperature here was naturally lower 

 than that of a sweet potato storage house, probably about 2.0° to 4.5° 

 C. All these potatoes were more or less decayed and Gibberella saubi- 

 netii was recovered in pure culture from 67 per cent. The controls 

 were also decayed, but G. saubinetii was not isolated from any. 



Experiment IV. — In this experimeiit the sweet potatoes (40) were 

 first placed in cold storage for one week and then inoculated by inserting 

 spores and hyphae into a wound, after which they were returned to cold 

 storage. Before inoculation one lot was disinfected as above in formalin 

 and wrapped. The potatoes were all decayed when removed from 

 storage. Gibberella saubinetii was recovered from 90 per cent of the 

 treated and 40 per cent of the untreated. 



Gibberella saubinetii renders the sweet potatoes at first spongy in 

 texture and brown in color. At a later stage, as moisture escapes, the 

 tissue becomes firmer and finally hard and mummified. The brown 

 color is later replaced by a pinkish-brown tint. 



