Nov. 1, 1925 
Ophiobolus graminis and Take-All of Wheat 
817 
A third experiment was carried out on a small plot of sterilized 
soil. This was divided into three parts, and each part was inoculated 
in the fall of 1922 with one of the strains of the parasite. Goldcoin 
wheat seed was sown in this soil in the fall ana about 400 plants 
developed to the seedling stage, when all but 57 became diseased and 
died in the fall. Fifteen plants of those living were in the soil inocu¬ 
lated with the New York strain of the fungus, 28 in that inoculated 
with the Oregon strain, and 14 in that inoculated with the Arkan¬ 
sas strain. Plants growing in uninoculated control soil grew thriftily 
until cold weather came on. In the spring only 16 plants remained 
alive in the plots which had been inoculated, and these plants showed 
no signs of disease. All of the plants in the uninoculated control 
ilot were winterkilled. Owing to the unoccupied space in the inocu- 
ated and uninoculated soils in the spring, it was decided to plant 
Marquis seed in both plots to determine whether the fungus was 
still living in the soil and pathogenic. This was done on April 27, 
and the 16 Goldcoin plants were allowed to remain in the inoculated 
plot. By May 17 all of the Marquis plants growing in the last- 
mentioned plot commenced to turn yellow and soon developed a 
severe case of typical take-all seedling blight. About 95 per cent 
of these plants died in a short time, while the plants growing in the 
uninoculated control soil developed normally. 
The 16 overwintered Goldcoin wheat plants growing in the infested 
soil showed no signs of disease until the last of May, when they 
turned yellow and died. It is believed that the winterkilling of the 
Goldcoin control plants and the escape of the plants growing in the 
infested soil is explained on the basis of irregularities in snow drifting 
during the winter. 
STUDIES WITH INFECTED PLANT TISSUE 
Plant material obtained from the experiments dealing with host 
susceptibility to the New York strain of the parasite were employed 
in this study on overwintering. In one case five No. 00 ash pails 
(5 gallons capacity) containing infected stubble in infested soil were 
left outdoors over winter. This stubble was rooted in the soil, and 
the soil was not disturbed, except when stubble was removed for 
purposes of making examinations for perithecia. In another case the 
infected stubble was removed from the soil and placed in open 
earthen flowerpots. In both cases the material without protection 
was exposed to the winter weather. 
Examinations were made on October 17, 1922, and perithecia were 
forming on the culms just above the crown in both lots of stubble. 
By January 3, 1923, asci had developed and many contained imma¬ 
ture spores. Numerous paraphyses were also present. By April 1 
the ascospores appeared mature, and those from one plant were 
tested for germination. It was found that 4.5 per cent of the asco¬ 
spores germinated when placed in distilled water on a slide under a 
cover glass. The same plant with the remaining fruiting bodies was 
then placed outside in its previous location, and on May 1 this plant 
was brought into the laboratory with several others, and ascospores 
from all of them were tested for their viability as before. Spores from 
the plant previously tested still showed about the same percentage of 
germination, while spores from other plants gave practically 100 per 
cent germination. Some of these spores were obtained from fruiting 
