PLATE I 
A. —Irish Cobbler potatoes grown under field conditions in soil inoculated with a 
pure culture of Corticium vagum. Plant grown from tuber planted April 26, showing 
the destruction of the primary growing point and uninjured secondary stem. Twenty- 
five per cent of the growing points of the primary shoots of the crop planted on this 
date were destroyed (Table I). 
B. —Same as A except that plant was grown from tuber planted May 7. A total of 
25.5 per cent of the primary buds of this crop were destroyed. 
The photographs illustrate how the growing tips of the primary shoots growing at 
the lower temperatures were attacked and killed by the fungus. Later secondary 
shoots arose from the primary stems which with the advent of higher soil tempera¬ 
tures grew so rapidly through the soil as to escape uninjured. The decreased patho¬ 
genic power of the fungus at the higher temperature no doubt aided in this (escape. 
C. —Potato plot at Plainfield, Wis., showing the disastrous effects of Corticium, vagum 
on the potato crop during the cool season, 1918. The third row from the right was 
planted with sclerotia-covered, untreated tubers. The plants in the rows on either 
side were grown from tubers equally “scurfed’’ but treated with mercuric chlorid. 
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