816 
Journal of Agricultural Research 
Vol. XXXI, No.» 
showed marked injury. Plants grown in the same manner and under 
the same conditions in uninoculated soil remained healthy. 
Waters (15) found that pure cultures of this organism were patho¬ 
genic on wheat plants growing in tubes of sterilized soil to which a 
pure culture of Ophiobolus graminis had been added. Kirby (7) 
also found that wheat plants developed the characteristic symptoms 
of take-all when grown in soil inoculated with pure cultures of this 
fungus. 
OVERWINTERING OF THE PARASITE 
These studies were carried out with three kinds of material: (1) 
agar cultures of the parasite in ordinary test tubes; (2) artificially 
inoculated soil; and (3) diseased plant material. All of the experi¬ 
ments were conducted during the winter of 1922-23, which was 
unusually severe at Madison, Wis. 
PURE-CULTURE STUDIES 
All three strains of the parasite, as used in previous experiments, 
were cultured on potato-dextrose agar in test tubes. After a good 
growth of mycelium was obtained the cultures were placed outdoors 
in an exposed position throughout the winter. In the spring it was 
found that several tubes had burst, due to the freezing of the agar. 
Transfers of the mycelium from all of the overwintered tubes showed 
that all of the cultures were alive. In all cases vigorous cultures of 
the three strains were obtained. 
STUDIES WITH ARTIFICIALLY INOCULATED SOIL 
An experiment was conducted with three lots of soil contained in 
6-inch metal cans. This soil was inoculated on October 18, 1922, 
with the mycelium of the New York, Arkansas, and Oregon strains 
of the parasite. Goldcoin wheat seed was planted at the time of 
inoculation. The plants showed signs of disease on November 22, 
1922, and at this time they were removed from the soil as completely 
as possible, including the roots, and the soil was left out of doors 
throughout the winter. All of the plants removed from the soil 
were examined carefully for perithecia, but none were found. On 
March 26, 1923, Goldcoin wheat seed was again planted in all the 
cans. Early in May take-all developed in all of the 21 plants 
growing in the soil which had been inoculated with the Oregon strain 
of the parasite. The disease did not develop in plants growing 
in the soil inoculated with the New York or Arkansas strains and 
the disease was mild in the plants growing in the soil inoculated with 
the Oregon strain. 
A second experiment was conducted in exactly the same manner and 
at the same time as the one just described, except that no seed was 
planted in the soil in the fall after inoculation. In' the spring 
Goldcoin wheat seed was sown, and a severe case of take-all developed 
in all of the 21 plants growing in the soil which had been inoculated 
with the Arkansas strain of the parasite. No disease occurred in 
soil inoculated with the Oregon or New York strains of the fungus, 
and more occurred in the uninoculated controls in either experiment. 
It is not known just why certain strains of the fungus were lolled dur¬ 
ing the winter. Possibly unevenness of snow cover may have been 
the cause. 
