84 
Research Bulletin No. I 
being placed in the storage cellars. For this purpose the best 
results were secured thru the use of either formalin dip, formalin 
vapor, or the lime-sulfur wash. Not only did the tubers in these 
lots show a very small percentage of dry rot but the tubers them- 
selves were in excellent condition otherwise when removed in 
April. The storage time, it should be remembered, employed in 
this experiment is longer than would ordinarily be employed by 
the average farmer and this gave the treatments a severe test. 
Under ordinary farm conditions the development of the formalin 
vapors is not easily secured and therefore we would particularly 
recommend the use of the formalin dip as the easiest method to 
employ and one that should give excellent results in practice. 
In connection with the above experiment a quantity of the 
World's Fair tubers were selected that showed bundle blackening 
or stem-end rot. The stem ends of these tubers were cut away 
till none of the discolored tissue remained. These tubers were 
then stored for the same length of time with the lots above 
mentioned with the following results: 
Table 27. — Effect of removal of the discolored stem ends. 
Total num- 
ber of tubers 
Number show- 
ing stem-end 
rot 
Per cent show- 
ing stem-end 
rot 
Number show- 
ing dry rot 
Per cent show- 
ing dry rot 
1129 
24 
2.14 
426 
37.73 
This experiment clearly show r s that the removal of the stem 
end of tubers showing characteristic stem-end rot tends thru 
wounding the tubers to greatly increase the amount of rotting 
due to dry rot and hence could not be practiced with safety in 
the control of the bundle blackening. 
SUMMARY AND CONCLUSIONS. 
1. The dry rot of the Irish potato tuber herein described is 
primarily a disease of mature tubers. 
2. This rot is of great economic importance thru the serious 
destruction of the tubers while in winter storage. 
3. This dry rot has been shown by numerous infection experi- 
ments to be due to a new species of Fusarium, herein described 
under the name Fusarium tubcrivorum sp. n. Wilcox and Link. 
4. This fungus has been shown to be incapable of infecting 
any other part of the potato plant than the ruber. 
5. This fungus cannot invade the tuber until it has practically 
attained maturity and then only thru wounds. Infection thru 
scab spots, lenticels, or the eye seems to be impossible. During 
