154 
Journal of Agricultural Research 
Vol. VIII, No. 4 
Flask experiments. —In one experiment the fungi were grown on 
liquid media in 100 c. c. Erlenmeyer flasks. About 50 c. c. of liquid were 
poured into each flask. Dox’s solution plus 2 per cent of dextrose was 
used with all the fungi except the species of Glomerella and Neofabraea. 
These did not grow well on this solution, so apple juice about + 5 was used 
as a substitute. The flasks were placed at the particular temperatures 
immediately after inoculation. The experiment was started on April 
16 and was concluded two weeks later. The fungus growth was 
filtered out by means of 
filter papers that had 
previously been dried 
and accurately weighed. 
After the fungus mass 
had been dried to con¬ 
stant weight, a second 
weighing was taken, 
the difference between 
the two weighings repre¬ 
senting the dry weight of 
the fungus. The results 
are shown in figure 13. 
The growth of some of 
the fungi was rather poor 
on the medium used, and 
in such cases the tem¬ 
perature response was 
small. It is interesting 
to note that Sclerotinia 
cinerea , Glomerella cin- 
gulata , and Sphaeropsis 
malorum , fungi which 
have given very decided 
temperature contrasts in 
other experiments, have 
in this case given practi¬ 
cally none. Neofabraea 
malicorticis has also given little contrast but did not show great sensi¬ 
tiveness to temperature in the experiments on fruit. With the species of 
Botrytis, Penicillium, and Aspergillus used there was a very decided drop 
in growth between 25 0 and 30°. Botrytis cinerea and Aspergillus niger 
had an optimum at 25 0 , while the optimum for Penicillium expansum 
was 20 0 instead of 25 0 as in the experiments on fruit. None of the fungi 
made enough growth at o° to produce a measurable quantity of mycelium. 
With many of them there was no evident growth. All of these, however, 
produced a vigorous growth when later removed to warmer temperatures. 
Fig. 13.—Graph showing the growth of apple-rot fungi in liquid 
media. 
