82 
Research Bulletin No. 1 
frost before the vines have fully matured may be sufficient to 
account for the presence of a thinner and more readily pene- 
trable skin than might be found under other circumstances. 
A histological examination of tubers from various sources tends 
to support this explanation tho further studies are required to 
put the matter beyond doubt. 
The failure of stem inoculations, or at least the very weak 
infection there found, would lead one to suppose that there was 
some substance in the stem, not found in the tuber, which tended 
to render the stem more immune against invasion by this fungus. 
The further fact that young tubers are infected neither in the 
field nor readily in the laboratory is still further evidence of this 
same sort. The distribution of solanin in the different parts of 
the potato plant is known to agree fairly well with the observed 
facts of inoculation. The exact relationship of solanin distribu- 
tion and its relative abundance in different parts of the same 
variety of potato and in different varieties is now being investi- 
gated in this laboratory. 
It should be stated that it has been shown by one of our 
colleagues* that the continuous growing of potatoes in the hot 
soil of eastern Nebraska apparently tends to result in weakened 
vigor. This tendency may be largely overcome thru the use of 
a mulch or the importation of seed from a cooler climate. Just 
what, if any, effect these conditions may have upon the develop 
ment of the skin or the distribution of solanin remains to be 
determined. 
METHODS OF CONTROL. 
The following experiments were conducted to learn if any 
method of treatment might be employed by which the rotting of 
the tubers during storage might be largely or entirely prevented. 
Arrangements were made to conduct these experiments in the 
cement potato cellar of Lincoln Davis near Gordon, Nebraska, 
and to him we are indebted for his enthusiastic interest and 
assistance in this phase of the investigation. A total of eighty- 
one bushels were employed in the experiment and these were 
divided into ten lots of about eight bushels each and treated 
before being placed in storage, as follows : 
1. Flowers of sulfur. The tubers were rolled in this powder so 
that their entire surface was covered. 
2. Air-slaked lime. The tubers were thoroly dusted over with 
this powder. 
* Emerson, R. A., Bui. 97 Nebr. Agr. Exp. Station. 
