14 Research Bulletin No. g 



producer in his 19 13 paper, there is a reference in the 19 12 paper by 

 Jamieson and Wollenweber (16) to a wilt produced by F. tri- 

 chothecioides. They referred to inoculation experiments, and 

 report wilting in 12 days, "accompanied by a yellowing of the 

 leaves and a discoloration of the tissue." The results of all of the 

 writer's attempts of 1911-1912 to produce wilting of potato plants 

 with F. trichotkecioides, excepting one, were negative. During the 

 past winter, however, it was noticed again and again that sprouts 

 of tubers experimentally infected with this organism were dying. 

 Microscopic and cultural studies left no doubt that this organism 

 was responsible for the death of the sprouts. 



Encouraged by these observations, the writer carried out some 

 preliminary experiments on potato plants. Quartz was sterilized in 

 6 inch flower pots in the autoclave, and 8 plants that were about 

 10 cm. high were transplanted into these, the stems of some being 

 smeared with rice infected with F. trichothecioides, and those of 

 others with rice infected with F. oxysporum. The plants so inocu- 

 lated and the controls were kept under bell jars. In three days the 

 three plants smeared with F. oxysporum and two smeared with F. 

 trichothecioides were dead, while the third one of the latter set and 

 the controls remained healthy. The experiment was also conducted 

 with potato plants growing in the open bench in the greenhouse, with 

 similar results. The soil in this case was not sterilized. 



The potato plants used in the following experiments were grown 

 from sterilized tubers of the Early Ohio and Red Cobbler varieties 

 in soil in 6 inch pots which had been thoroughly sterilized by 

 heating in an autoclave for 4 hours on two consecutive days at 



15 lb. pressure. The soil was watered with sterile water through- 

 out the experiments. 



On February 15, fifteen pots were planted with Early Ohio 

 tubers and the soil of one set of 5 was infected with rice infected 

 with F. oxysporum, of another with rice infected with F. trichotheci- 

 oides, while the third set was left as a control. The controls came 

 up in due time, while not a single one of the others came up. This 

 experiment was repeated several times, but in no case was so strik- 

 ing a result obtained, although it often happened that some sprouts 

 showed lesions, that some failed to come up, and that some were 



