826 
Journal of Agricultural Research 
Vol.XXI.No.ii 
great majority of the tubers, 64.6 per cent, were “browned 0 ; a large 
portion, 26.2 per cent, were “yellow 0 while a comparatively small 
though appreciable number, 6.6 per cent, were “not discolored. 0 Thus 
the data indicate that this fungus when present in potato tubers is 
accompanied in the majority of cases by distinct discoloration but that 
frequently the discoloration is very light or even entirely absent and 
that therefore discoloration of the tubers is not a reliable basis for judging 
whether or not this fungus is present. 
Table I. Relation between stem-end vascular-tissue discoloration and occurrence of 
organisms in potato tubers grown during the seasons of 1915, 1916, and 1017, under 
various conditions, some by diseased and others by healthy plants a 
Organisms isolated. 
Tubers with— 
“Jelly-end” 
and slight 
dry stein- 
end rots. 
Inner vascular region at stem end— 
Totals. 
Blackened. 
Browned. 
Yellowed. 
Not dis¬ 
colored . 
Verticillium albo- 
atrum. 
8 .S 
31 
i -5 
9. 1 
22 
I. I 
30-7 
I > 355 
64.6 
16. 5 
55 ° 
26. 2 
3-6 
139 
6.6 
I 7 * 3 
2,097 
100 
Fusarium radici- 
cola. 
12. 2 
43 
8.3 
12 . I 
29 
5-6 
7-5 
33 i 
64. 2 
2.8 
94 
18. 2 
o -5 
19 
3-7 
4.2 
5 i 6 
100 
Fusarium oxy- 
sporum. 
4-5 
16 
5-4 
18.8 
45 
15.2 
4.0 
176 
59 *7 
1.4 
48 
I 6. 3 
o -3 
10 
3-4 
2.4 
295 
100 
Other Fusarium 
species. 
4.2 
6.9 
3-7 
9 
4. 1 
2.7 
119 
54-3 
1. 6 
52 
23-7 
0.7 
24 
11. 0 
1.8 
219 
100 
Miscellaneous 
fungi. 
53-9 
191 
6.1 
3^-3 
87 
2.8 
33-2 
1,463 
46. 4 
27.2 
906 
28. 7 
I 3 * 3 
506 
16. 0 
26. 0 
3,153 
100 
None. 
16. 4 
58 
1. 0 
20. 0 
48 
.8 
21. 9 
969 
16.5 
5 o -5 
1, 680 
28.7 
81. 6 
3 , 101 
53 -o 
48.3 
Si 856 
100 
Totals. 
roo 
354 
2.9 
COO 
240 
2 . O 
too 
4,413 
36.4 
100 
3,330 
27.4 
100 
3,799 
31*3 
roo 
12,136 
100 
Sh T S the ™ m ! w ° f Ul ' ws which in culture gave the results inch- 
mmhSiSS fi , k intersecting columns; the lower right set of figures gives the percentage this 
age of the totaf tubers^rTth^verUcaf column ^° nZ ° n ^ a ^ coIumn : a " dthe “PP« left set gives the pe'rcent- 
