472 
Journal of Agricultural Research voi. xxvi. No.» 
vigor as follows: First, the extent of decay in the susceptible region above 
the attachment of the cotyledons; second, the extent of vascular dis¬ 
coloration above the region of cortical deca}^; third, the extent of dam¬ 
age that the taproot and rootlets have sustained; and, fourth, the vigor 
of root growth. 
Alaska compared with No. 330 showed no difference in extent or 
character of injury. All plants were so badly decayed that seed produc¬ 
tion was not likely. All varieties suffered approximately equally in 
the susceptible zone at the base of the stem and in the extent of vascular 
discoloration above this region. The varieties of Canada field pea showed 
a more vigorous development of rootlets above this injured region, and 
these rootlets showed fewer lesions than were present on those of the 
canning varieties, whether of the starchy or wrinkled types. The 
extreme differences in root production between the field pea and canning 
types are shown in Plate 1. 
A final comparison of Alaskas with No. 330 was started April 7 at a 
soil temperature of 27 0 C. from the time of planting. All plants were 
far more vigorous in the increased sunlight obtaining at this season. 
Very few plants of either variety wilted, but all were considerably 
stunted until May 1, when improvement in growth and color was noted. 
On May 15 the Alaskas were inferior in vigor to No. 330 (Plate 1, A) 
and a comparison of the root systems when washed from the soil showed 
greater difference than that shown by the tops. Although the only 
living roots were those emerging from above the decayed stem bases, 
these were far more extensive and freer from injury on the No. 330 than 
on the Alaska plants. 
The evidence contained in these experiments, limited though it is, 
indicates clearly that among the varieties of peas tested, there is no 
conspicuous degree of resistance to decay at the base of the stem. The 
plants which are able to develop in spite of this decay, do so by virtue 
of the vigor with which they can send out new roots above the point 
of injury, and perhaps to some degree to the resistance of these rootlets 
to destruction by the fungus which may be combined with resistance of 
the vascular system to invasion. The susceptible region at the base 
of the stem does not appear to become more resistant as the plant grows 
older, though the damage to this region is less serious to an older plant. 
These experiments also suggest that an accurate control of soil conditions 
is not sufficient in comparing varieties of peas for resistance, but that 
intensity and duration of illumination which indirectly affect the vigor 
of root growth may also affect resistance. Further study of resistance 
was not made because it became clear that even should a far greater 
degree of resistance to this fungus be found, only a small degree of progress 
would be made in finding a plant that would survive in most diseased 
fields, provided resistance to this fungus was not coupled with resistance 
to other more important diseases. 
PATHOGENICITY OF SPECIES OF FUSARIUM ISOLATED FROM 
VASCULAR BUNDLES OF DISEASED PEAS 
During two summers great numbers of isolations were made of fungi 
present in discolored vascular bundles of diseased pea plants in order to 
determine whether any among these fungi which certainly contribute 
toward the destruction of plants are capable of acting as primary para¬ 
sites. Material was collected largely in Wisconsin, with many representa- 
