90 BULLETIN 934, TJ. S. DEPARTMENT OE AGRICULTURE. 
(14) In an inoculation experiment on the roots of pines 1| months 
old, Corticium vagum and Pythium deoaryanum were found able 
to cause the death of seedlings which had already developed rigid 
stems and to destroy the younger parts of the roots of seedlings which 
they were unable to kill. Indications were also obtained of similar 
but less vigorous action by Fusarium moniliformis and F. ven- 
tricosum. 
(15) Data are given confirming the general belief that thick sow- 
ing favors the disease and indicating that soil acidity is, in general, 
unfavorable. Preliminary data on the relation of temperature and 
moisture to the disease are also presented. The parasitic activity of 
Pythium d&baryanum in steamed soil was in one extensive test con- 
siderably decreased, following the inoculation of the soil with various 
saprophytes; this indicates both that competition of different fungi 
is a factor to be considered and that the inoculation of treated soil 
with saprophytes may sometimes prove of value in increasing the 
efficiency of heat disinfection. It is pointed out that with such a com- 
plex of parasites capable of producing identical symptoms on a num- 
ber of different hosts, no relationship between environmental factors 
and the disease can be expected to hold in all cases. 
