Nov. II, 1918 Sweet-Potato Storage-Rots 357 



the other remained sound. From this experiment it seems that medium 

 temperatures are more favorable to Boirytis cinerea than the higher or 

 lower ones. 



Boirytis cinerea produces a grayish, soft, somewhat watery rot (PI. 

 27, D). The tissue of the sweet potato pulls out in strings when broken 

 apart. It has a somewhat starchy odor. 



EPICOCCUM SP. 



Although this fungus can not be regarded as of much economic im- 

 portance, it was so often isolated from rotted sweet potatoes held at low 

 temperatures that it can not be passed over without mention. It grows 

 rather slowly and is probably able to cause decay only at such tempera- 

 tures at which the competition of other fungi is reduced. 



From a lot of sweet potatoes which had been thoroughly washed and 

 then stored at 0°, 5°, and 10° C. Epicoccum sp. was about the only 

 fungus isolated. Later a series of experiments were conducted in which 

 sound potatoes were inoculated with pure cultures by the "well" method 

 and exposed to the temperatures of chambers 3 (7.19° C), 6 (14.4° C), 

 9 (20.9° C), and II (26° C.) of the Altmann thermostat. All the 

 potatoes in chamber 3 were slightly to completely decayed in three 

 weeks. In the other compartments they remained sound. 



Epicoccum sp. produces a slow, firm rot. The tissue is rendered at 

 first slightly yellowish followed by a reddish browTi color (PL 27, E). 



GIBBERELLA SAUBINETII 



From the number of species of Fusarium that can be isolated from 

 decayed sweet potatoes only a few have been shown to cause storage 

 rots. Because of the almost omnipresence of some of the species of 

 Fusarium an immense amoimt of work was done with these fungi. 

 Strange to say, those species most frequently isolated are those which 

 the writers were unable to prove parasitic or rot-producing organisms. 

 On the other hand, those species shown to be capable of causing decay 

 are, comparatively speaking, seldom found under natural conditions. 



Experiment I. — Experimental work with this organism as a storage- 

 rot fungus was started in 1914, when 75 potatoes after a thorough wash- 

 ing were divided into two lots, one of which was disinfected in formalin 

 (i :20o) for 30 minutes. Both lots were inoculated with Gibherella sav^ 

 binetii (Mont.) Sacc. from pure culture by inserting spores and hyphae 

 into wounds. The treated lots only were wrapped in oiled paper. The 

 two lots were then placed in storage, the temperature of which was 

 maintained at about 2.0° C. They were left in storage for four months, 

 when they were removed and isolations made from each potato. G. 

 savhineiii was recovered in pure culture from only 20 per cent of the 

 untreated and from 34 per cent of the treated lot. From the other 



