EFFECT OF NATURAE EOW TEMPERATURE ON 
CERTAIN FUNGI AND bacteria 
By H. E. Bartram, 
Assistant Plant Pathologist , Vermont Agricultural Experiment Station 
The effect of the very intense cold of northern winters on the life and 
viability of fungi and bacteria does not seem to have been tested exten¬ 
sively, yet its importance in checking the spread of plant infections from 
these sources would appear to be very great. 
Wolf 1 has shown that certain parasitic and saprophytic fungi remain 
present and alive in Nebraska orchards during autumn, winter, and 
spring. The majority of the species are saprophytic, the more common 
ones being Alternaria spp., Cladosporium spp., and Penicillium expansum . 
Only one parasite, the cause of leafspot, was present in abundance 
regardless of temperature. He found more spores in the air in neglected 
orchards than in well-cared-for ones and also found them to be much 
more abundant everywhere than commonly has been supposed. All his 
determinations were made by exposing plates at various places in the 
orchard and then carefully studying and determining the colonies after 
they had developed. 
In the present study certain known fungi and bacteria were exposed 
in pure cultures to the low temperature of the winter months. The 
organisms were started upon nutrient agar in test tubes—i. e., allowed 
to grow at laboratory temperature for about one week after inoculation— 
and then these cultures were placed in a comcrib where there was a free 
circulation of air, but where they were protected from the rain and snow. 
The tubes were inoculated between December io and 16 and were 
exposed in the outhouse on December 21, with the exception of Actino¬ 
myces organicus, which was not exposed until December 31. The cul¬ 
tures were undisturbed throughout the winter, during which time a 
minimum temperature of — 24 0 C. was reached. The medium did not 
dry up to any extent, but was rather moist when brought into the labora¬ 
tory, as the frequent freezings and thawings seemed to impair the solidi¬ 
fying power of the agar. 
Oh April 14 the cultures were brought into the laboratory and tested 
immediately for vitality. This was done by transferring part of the 
exposed culture to fresh nutrient-agar slants and allowing the new inocu¬ 
lations to grow at room temperature. In all cases except one the re¬ 
sponse to fresh agar was soon evident, but in the case of Actinomyces 
1 Wolf, F. A. The prevalence of certain parasitic and saprophytic fungi in orchards, as determined by 
plate cultures. In Plant World, v. 13, no. 7, P-164-172, fig. 1; no. 8, p. 190^202, fig. 4-5. 1910. 
(651) 
Journal of Agricultural Research, 
Dept, of Agriculture, Washington, D. C. 
bm 
Vol. V, No. 14 
Jan. 3, 1916 
Vt.—i 
