94 



Journal of Agricultural Research 



Table III. — Results of the inoculations of different varieties of potatoes with original and 

 reisolated strains of Fusarium vasinfectum 



Variety of potato. 



Number of 

 tubers. 



Incubation 

 period. 



Average 

 temperature. 



Percentage 

 of tubers 

 rotting. 



1855 



3i67>i855. 

 3263 



3243 ■ 



[Netted Gem 



I Idaho Rural 



[People's 



I Idaho Rural 

 Netted Gem 

 Burbank 

 Pearl 



I Green Mountain. 

 do 

 do 



f do 



J do 



1 do 



I do 



Days. 



"C. 

 25-5 

 25-5 

 25-5 

 21.5 



21-5 

 21-5 

 21-5 



18.3 

 18.9 



23-5 

 17.8 

 18.4 



23-5 

 24. 6 



Z2, 

 100 



>=reisoIation of. 



jElvLY-END ROT AND A TUBER DRY ROT CAUSED BY FUSARIUM RADICICOLA 

 JELLY-END ROT 



"Jelly-end" is the very appropriate name applied by growers to 

 potatoes affected with a field rot and a storage rot which annually cause 

 serious losses in the delta lands of California and in the irrigated sections 

 of Oregon and Idaho. 



Many of the tubers when dug show the characteristic soft rot at the 

 stem end, the affected portion easily separating from the rest of the 

 tuber (PI. XVI, XVII). The rot proceeds uniformly until the whole 

 tuber becomes a slimy mass within the entire skin. If allowed to dry 

 out, the skin sometimes persists as a loose attachment at the stem end, 

 or it may shrivel and wrinkle down on the affected part, in this stage 

 suggesting dry rot. 



The jelly-end rot is not a new disease, but nothing has been done to 

 establish the cause of the trouble. Orton (9, p. 5), discussing the wilt and 

 dry end-rot of potatoes in California, says: "An early form of this 

 Fusarium dry end-rot is frequently met with shortly after digging, and 

 potatoes thus affected are known to buyers as 'jelly-ends.' " Shear (13, 

 p. 6) says: "A serious feature of this disease [wilt] is that it forms a 

 means of entrance for other fungous and bacterial diseases of the tubers, 

 such as 'jelly-end' and dry rot." The examination of specimens from 

 different localities indicates that jelly-end rots may be caused by several 

 species of Fusarium. Wollenweber (21, p. 257-258, 264-265) isolated 

 both F. orihoceras and F. radicicola, and of this disease he says in part 

 (p. 265) : 



In Watsonville, Cal., in October, 1913, the writer found up to 80 per cent of Burbank 

 potatoes in a large acreage affected by this peculiar soft rot, which is quite different 



