Dec. 8,1933 
Fusarium Stem and Rootrot of Peas 
47i 
It is unfortunate that other plots on different types of soil were invaded 
by more vigorous parasites and ruined for comparative study of Fusa¬ 
rium injury. The simplest interpretation of this single comparison is 
that the presence of much organic matter in the soil favored the per¬ 
sistence of Fusarium. This interpretation is favored by field observa¬ 
tions which, when reviewed, show that the largest amount of damage 
from this fungus is, in as far as it can be distinguished, on soils high in 
organic matter. Whatever factors determining persistence may ulti¬ 
mately be distinguished, the fact is clearly established that the parasite 
is dependent upon soil conditions for its persistence, and that it is not 
always or perhaps even frequently able to become a limiting factor in 
pea culture. Even in the soil most favorable for its persistence that was 
found, its spread through the soil from year to year was small, amounting 
to only about 2 or 3 feet in two years. 
RESISTANCE OF VARIETIES OF PEAS TO FUSARIUM 
Inasmuch as it is a well known fact that Canada field peas appear to 
suffer less from root diseases than canning varieties, and that canning 
varieties differ among themselves, an attempt was made to determine if 
this difference in resistance is due to difference in resistance to this 
Fusarium. The varieties first compared were Alaska and Rice’s No. 330, 
varieties which Dr. Wilber Brotherton, jr., had found to show great 
difference in vigor in a field infested with several root parasites. After 
several preliminary trials had failed to show any marked difference in 
behavior toward the parasite, 44 plants of Alaska and 34 plants of Rice’s 
No. 330 were grown in uniformly inoculated soil at 27 0 C., the optimum 
temperature for infection. This experiment was started in a cloudy 
December when peas did not grow vigorously. Through an oversight 
the seed of No. 330 used was older than that of Alaska, a factor that may 
have given weaker plants of this variety. At any rate, the surviving 
Alaska plants grew more vigorously and gave more evidence of resistance 
than did those of No. 330. This experiment was repeated in January 
with the same result. 
When the method which was used in these experiments is considered, 
it will be seen that although it secures results in a short time it is open 
to the objection that it subjects the germinating seed to higher soil tem¬ 
peratures than they ever encounter in the field, a condition which may 
reduce resistance. Accordingly a new series was started on the last day 
of February in which the soil temperature was maintained at 15 0 C. for 
two weeks before the temperature was raised to an optimum for infection. 
About 30 plants of each of the following varieties were grown from seed 
produced the previous summer: 
Smooth peas—Alaska, Rice’s No. 330; wrinkled peas—Rice’s No. 13, 
Admirals (yellow), Eclipse, Horsford’s Market Garden; Canada field 
peas—Scotch Beauty, Canada White. 
One week after the plants were transferred to the higher soil tem¬ 
perature wilting began to appear, and on three sunny days half of the 
Eclipse, and a third of the Alaskas, yellow Admirals, and Scotch Beauties 
were thus destroyed. On March 21, when the Alaska plants were producing 
flower buds, all plants were washed from the soil and examined. Since 
there is much individual variation between plants of the same variety, 
an estimate of resistance is largely a personal judgment based upon a 
comparison of the damage that the plants have sustained and of their 
