64 
Journal of Agricultural Research 
Vol. XXIV, No. I 
History or seed and methods or planting. —^The seed used in all 
the experiments was from the same lots of the Late Wisconsin Hollander 
and Commercial Hollander strains. The Late Wisconsin Hollander was 
the strain of Hollander which has proved to be highly resistant to the 
Fusarium disease under field conditions, as recently described by Jones, 
Walker, and Tisdale {12). This seed was grown in 1917 by S. B. Walker 
at Racine, Wis. The seed of the commercial strain was obtained from 
the L. L. Olds Seed Co., Madison, Wis. No information could be had as 
to where and when it was grown, but it was considered a good representa¬ 
tive of the Commercial Hollander type. It had been proved to be about 
99 per cent susceptible when grown in “sick'' soil. 
In the first and third tests, three receptacles in each tank were planted 
with Wisconsin Hollander and three with the Commercial Hollander. 
Two of the three receptacles in each set contained “sick" soil and one 
contained sterilized soil. In the second experiment only two receptacles 
were used for a strain in each tank, one containing “sick" and the other 
sterilized soil. When the plants were well above ground, the stand 
was thinned to 10 plants in each receptacle, except in certain cases, and 
the surface of the soil was covered with a half-inch layer of mineral wool. 
The experiments. —^Four separate tests were conducted for measuring 
the influence of soil temperature upon the occurrence of yellows in cab¬ 
bage seedlings, three with naturally infested soil and one with artificially 
inoculated soil. Three of the tests were conducted during the winter of 
1917 and the spring of 1918, and one in the spring of 1919. In all three 
experiments with naturally infested soil the behavior of the host plant was 
similar, and the percentage of disease checked fairly closely. Of course, 
the intensity of light was greater in the spring than during the winter, but 
it was reduced in the spring by nailing cheesecloth on the inside of the 
roof of the greenhouse above the tanks. The final data were recorded 20 
days after the seed was planted; they show the percentage of yellows 
and the percentage of plants dead by this time. This length of period was 
chosen because in the first experiment all of the plants of the commercial 
strain at 32° C. had developed yellows within 20 days. 
Methods or expressing data. —^The data in the greenhouse experi¬ 
ments were taken daily after the disease began to develop. In the first 
four experiments the task of taking data consisted merely in recording the 
number of diseased plants and the number which died as a result of the 
disease. The percentage of yellows includes the plants which showed 
the disease in incipient stages as well as those which died from the dis¬ 
ease. Except in doubtful cases diagnoses of yellowed plants were made 
from the external symptoms in the leaves; the doubtful cases were cul¬ 
tured on agar plates. 
Experimental data. —^The data given in Table V and figures i and 5 
show that Fusarium congluUnaus is capable of producing yellows in 
both the susceptible Commercial Hollander and the resistant Wisconsin 
Hollander seedlings over a wide range of temperature, the minimum 
being 17^^ and the maximum about 35° C. At the lower temperatures, 
however, the disease developed more slowly and less destructively than 
at higher temperatures (fig. 6). The Wisconsin Hollander strain was 
even less severely attacked at the lower temperatures than the com¬ 
mercial strain. Plate 2, A-C, shows a contrast of the two strains grow¬ 
ing in “sick" soil at 17°. At 15° the disease did not develop even in 
the most susceptible strains. The optimum soil temperature for the 
occurrence of yellows in the commercial strain in naturally infested soil 
