Jan. 22, 1917 
Temperature Relations of Apple-Rot Fungi 
153 
but continued to grow when given a start at a higher temperature 
emphasizes the importance of immediate storage. It is interesting to 
note how little effect the delay in storage had upon Cephalothecium 
roseum and Neofabraea malicorticis. This is in agreement with the 
temperature responses shown in figures 2 and 7. The growth of 
Sphaeropsis malorum was delayed by immediate storage, and this was 
probably true of Sclerotinia cinerea also; but with the latter fungus 
no contrast was evident at the end of the experiment, as the fruit 
was practically completely rotten in the immediate as well as in the 
delayed storage. 
It should be noted that the species of Alternaria, Botrytis, Penicillium, 
and Volutella used produced no rot when stored immediately at commer¬ 
cial cold-storage temperature, while all have caused more or less rot at 
o° in laboratory experiments, Botrytis cinerea and Penicillium expansum 
producing rots 1 or 2 cm. in diameter in less than five weeks. ■ It is pos¬ 
sible that the air in the cold-storage plant sometimes dropped slightly 
below o° C. and that the explanation of the above contrast is to be found 
in differences in temperature, but the writers are of the opinion that it 
was due to differences in the maturity of the fruit; as the apples used 
in the commercial cold-storage experiments were much greener than 
any of those used in the laboratory tests. The importance of maturity 
of fruit in determining the amount of rot at low temperatures and the 
minimum temperature for the fungus has already been pointed out. 
It is interesting to note the almost entire absence of rot in the case 
of the apples washed in spore suspensions, only two apples out of the 
total of 140 becoming infected at all and these two specimens occurring 
in the case of delayed storage. The results strongly emphasize the im¬ 
portance of avoiding punctures and other injuries on fruit that is to be 
held in storage. 
TEMPERATURE EXPERIMENTS ON CULTURE MEDIA 
The various rot fungi were also tested at different temperatures on 
several different culture media. The behavior of the fungi on the fruit 
is of special interest because it is on this medium that they become of 
economic importance; but the apple is a living organism and when fruit 
is kept in storage for any length of time, its condition at a high tem¬ 
perature will become very different from that of similar fruit kept at 
low temperatures. Consequently, in determining the behavior of fungi 
at different temperatures * one must consider two living organisms, the 
parasite and the host, the former usually being favored by high tempera¬ 
tures and the latter being continually weakened by them. Culture 
media probably remains practically constant at the different tempera¬ 
tures used and therefore furnishes a fairer test of the temperature 
responses of the different fungi. It has been difficult, however, to get one 
medium which was satisfactory for the growth of all the fungi. 
