Potato Failures. 
11 
INJURIES. 
Plant Injuries .—Young plants suffer severely from its inva¬ 
sions and are often completely cut off by it before they reach the sur¬ 
face of the ground. Its attacks on the subterranean stems may bring 
about an abnormal development of tubers, which is usually spoken 
of as “Little Potatoes,” or the injuries may be of such nature as to 
interfere with the storage of assimilated food in the subterranean 
branches of the plant, thus bringing about an abnormal top de¬ 
velopment, and frequently green tubers form in the axil of the 
leaves. (See Bulletin 70 , p. 5 - 7 ). 
In an experiment with badly infested seed 32 per cent, of the 
plants were killed before they reached the surface of the ground; 
17 per cent, of the plants that reached the surface failed to pro¬ 
duce tubers, and only 50 per cent, of the seed planted produced 
plants that developed tubers large enough for No. l’s and many 
of these were scabby. On July 1 - 1 , 55 percent, of the living plants 
showed the corticium stage of this fungus. Seed selected from 
this lot, but free from the sclerotia stage, produced plants of 
which only 20 per cent, showed traces of the corticium stage. 
Plants in an adjoining experiment which were free from the rhiz- 
octonia and sclerotia stages were also free from the corticium 
stage. 
Scabbing of Tubers .—European investigation long ago at¬ 
tributed the pitting or scabbing of tubers to the attacks of Rhizoc- 
tonia. Our experiments and observations also show that its 
attacks on growing tubers frequently produce deep ulcers. Most 
of our scab is due to the attacks of this fungus. (See Bulletin 70 , 
p. ii). 
Rotting of Seed Tubers .—Observations show that seed tubers 
are frequently invaded by the light colored hyphse of this fungus, 
which gradually turn the flesh watery and soft. If the tubers are 
rotted early in the season, the plants are not only cut off from 
their food supply before they become well established, but they 
also suffer more or less from the attacks of the fungus. Such 
plants usually do poorly and frequently die before the close of the 
season. Numerous attempts to produce wet rot by inoculating 
healthy tubers with both the sclerotia and rhizoctonia stages 
have failed; however, a dry rot has occasionally developed. 
Five out of eight seed tubers infected with this fungus placed 
in sterilized sand on July 2 , 1903 , and examined three months later, 
were completely rotted by a wet rot produced by this fungus. 
The remaining three were also completely rotted at the end of the 
fourth month, while five check tubers which were free from the 
fungus remained sound. 
Five cultures taken from the different parts of each of these 
