Jan. 22, 1917 
Temperature Relations of Apple-Rot Fungi 
163 
Volutella fructi has been studied at different temperatures and under 
various conditions, 
(2) In the inoculations on apples all of the fungi grew at o° except the 
species of Fusarium and Glomerella, the former making no growth at 15 0 
and the latter none at io°. Sphaeropsis malorum had produced no evi¬ 
dent rot at 15 0 by the end of one week nor the species of Penicillium and 
Neofabraea at io° by the end of two weeks, while Scleroiinia cinerea pro¬ 
duced measurable rots at 5 0 in one week and at o° in two weeks. Neo¬ 
fabraea malicorticis had an optimum at 20°, Fusarium radicola at 30°, 
and all the other fungi at 25 °. With most of the organisms the growth 
rate dropped off rapidly above 25 °, but with the exception of N. mali¬ 
corticis all made some growth at 30°. 
In commercial cold-storage experiments on rather immature fruit 
Penicillium expansum continued to develop at o° in the case of delayed 
storage, but was unable to grow at that temperature in the case of 
immediate storage. 
(3) On corn-meal agar in petri dishes all the fungi used but the 
species of Cephalothecium, Fusarium, Glomerella, and Sphaeropsis grew 
at o°, while these four made a fair growth at 5 0 . The optimum and 
maximum temperatures for the various fungi were the same as in the 
fruit-inoculation experiments. 
(4) The spores of the species of Alternaria, Botrytis, Penicillium, and 
Sclerotinia had germinated in corn-meal agar at o° at the end of one 
month; but those of the species of Aspergillus, Cephalothecium, Fusa¬ 
rium, Glomerella, and Pestalozzia had not. At 5 0 germination had 
. taken place with all of them but Aspergillus niger at the end of the 
month. 
(5) The temperature responses of the various fungi have been greatly 
modified by the food material upon which they were grown. Fusarium 
radicicola and Glomerella cingulata had a lower minimum temperature 
on corn-meal agar than on fruit and the early growth of the species of 
Alternaria, Botrytis, Neofabraea, and Penicillium used was much less inhib¬ 
ited on corn-meal agar at low temperatures than on the apples. In the 
case of fruit inoculations with Penicillium expansum and others of the 
weaker parasites the minimum has varied with the maturity of the fruit. 
(6) With most of the fungi the initial incubation stages of growth 
on the fruit have been more inhibited by low temperatures than the 
later ones. With the weaker parasites like Penicillium expansum it 
is apparently this initial stage of decay rather than germination that 
determines the minimum temperature for fruit rot. 
(7) The results show the importance of immediate as compared 
with delayed storage; the value of temperatures of 5 0 or io° in short 
periods of storage and of o° in longer ones and that the minimum tempera¬ 
ture will vary with the prevalent fungus and with the variety and matur¬ 
ity of the fruit. 
