200 Journal of Agricultural Research voi. v, no. s 



Butler County, and in Dutchess County, N. Y. To judge from corre- 

 spondence with growers it is a field rot and a storage rot of considerable 

 importance. Infected tubers placed in storage rot badly the following 

 spring; some of the growers are reported to have lost 50 per cent from 

 dry-rot. Whether unaided F. eumarlii produces a wilt and a rot as a 

 result of planting infected seed is not known. More likely it is secondary 

 to infection by F. oxysporum or Verticillium albo-airum in such cases. 



INOCULATION OF POTATO TUBERS WITH FUSARIUM EUMARTII 



F. eumartii 2932; isolated on January 3, 1914, from a stem-end dry- 

 rotting tuber (Heath's Medium-Late Surprise variety) from Tower City, 

 Pa. Culture used, 7-day old pionnotes on cotton stem. 



F. eumartii 2947; isolated as above on January 15, 1914. Culture 

 used, 7-day-old pionnotes on potato cylinder. 



F. eumartii 3040; reisolation of 2947, April 23, 1914, from rotting 

 Idaho Rural potato, 19 days after inoculation at 23.1° C. Cultures 

 used, 2 2 -day-old pionnotes on potato cylinder, and in a subsequent trial 

 2-months-old cultures on rice, Melilotus alba, and cotton stems. 



F. eumartii 2958; isolated on January 28, 1914, as recorded in Nos. 

 2932 and 2947. Culture used, 7-day-old pionnotes on potato cylinder. 



All tubers of the five varieties mentioned which were inoculated with 

 the several original and reisolated strains of this species of Fusarium 

 showed a progressive rot beginning at the points of inoculation in each 

 case; many of the lenticels were invaded, sunken, and with the subjacent 

 parenchyma browned. People's variety was the most susceptible, the 

 others being affected in the order named — Early Rose, Jersey Peachblow, 

 Netted Gem, and Idaho Rural (PI. XIX). However, even in the last- 

 mentioned variety there was 100 per cent of infection about the inoculation 

 pricks and lenticel invasion of all tubers. Some of the inoculated tubers 

 were completely softened ; others showed a dark-brown zone about the inoc- 

 ulation prick, surrounded by an extensive watery zone of softened tissue. 

 At low temperatures a typical slow dry-rot was produced. The respec- 

 tive organisms were recovered in every attempt made: Nos. 2932 and 

 2947 from all varieties used; 2958 from the Idaho Rurals; 3040 in first 

 trial, one reisolation from the Idaho Rurals, and one from the Netted 

 Gems; in a later experiment five reisolations were made from the Idaho 

 Rural variety. 



Table V gives the results of the inoculations with F. eumartii. 



