82 
Journal of AgricuUural]Research 
Vol. XXIV. No. I 
lows at 19 per cent moisture was 29 per cent greater than at 23 per cent 
moisture and 25 per cent greater than with 26 per cent moisture. At 
first sight, this condition suggests that because of the reduced functional 
root system the affected plants were unable to take up the necessary 
amount of water from the soil with 19 per cent moisture. These results 
are probably partially explainable on this basis, but the more rapid 
death rate wilii 26 per cent moisture than with 23 per cent and the 
general appearance of the plants in the former case suggest the operation 
of some factor in addition to deficient water supply. The fact that be¬ 
yond a certain point both the general vigor of the highly susceptible 
plants and the percentage of yellows in them decreased with an increase 
in percentage of soil moisture suggests a reduction in the virulence of 
the Fusarium. It is possible, therefore, that the reduced oxygen supply 
in the soil due to increased water content affects both host and parasite. 
INFnUENC^ son. moisture upon thjs growth op CABBAG]^ spbduings 
It is interesting to note in this connection the influence of soil moisture 
upon the growth of cabbage seedlings themselves. This investigation 
was made simultaneously with the study of the influence of soil moisture 
upon the occurrence of yellows. The dry weight of the plants was used 
as an index of growth in this case, as previously, and the plants ^own 
in sterilized soil as controls for the second test in the study of the disease 
were used for the determinations. The plants were cut at the surface 
of the soil 35 days after seeding and dried for 16 hours at 95° C. Six 
plants from each of the two receptacles were used. The average weight 
per plant of the 12 plants is given in Table XIV. 
TabI/P XIV .—Dry weight of cabbage seedlings grown in soil with different moisture 
contents 
Soil moisture (per cent). 
19 
0.478 
23 
o- 343 
26 
Dry weight per plant (gm.). 
0.251 
1 
It will be seen from the foregoing table that the soil v/ith 19 per cent 
moisture was the most favorable for increase in dry weight. Also, the 
vigor of the plants, rich leaf color, and extensive root system indicated 
that the plants were in a healthy, flourishing condition. Contrasted 
with these, the plants growing in soil with 26 per cent moisture showed 
decided stunting, yellowish-green leaf color, and a greatly reduced root 
system. In addition, the roots were brown and small. Both the dis¬ 
coloration and the disintegration were even more pronounced in roots 
grown in the '‘sick” soil, probably because of the action of secondary 
organisms following the Fusarium. The plants grown in the soil with 23 
per cent moisture exhibited characters between tiiese extremes. 
The results of these experiments show that cabbage is not a high- 
moisture-loving plant and that the Fusarium is more pathogenic in 
soil with low moisture content. 
SUMMARY 
(i) Cabbage yellows, a disease caused by the vascular parasite Fusa¬ 
rium conglutinanSf has been observed to develop in its most destructive 
form in southeastern Wisconsin only under conditions of hot, dry weather. 
