FURTHER STUDIES OF THE ROTS OF STRAWBERRY FRUITS. 3 
(4), and others, and it is apparently of first importance in the straw- 
berry. 1 
IMPORTANCE OF LOW TEMPERATURE. 
The careful studies of Miss Ames (1) indicate the close relation 
between temperature and the rate of growth of Rhizopus. Rhizopus 
grows very slowly at a temperature of 10° C. (50° F.). The rate of 
growth increases very rapidly with the rise of temperature above that 
point, however, so that the fungus will develop more in a short time 
at a relatively high temperature than in a much longer time at a 
lower temperature. Miss Ames found, for instance, that RMzopus 
nigricans would produce mature sporangia in 36 hours at a tempera- 
ture of 33° C, while at temperatures of 10° to 12° C. three weeks were 
required. 
The importance of low temperature in reducing rots of strawberries 
was strikingly shown by tests conducted in connection with experi- 
mental shipments between Monett, Mo., and St. Paul, Minn. Similar 
boxes of strawberries of the Warfield variety were inoculated with 
spores and mycelium of Rhizopus nigricans through needle wounds. 
The berries, at a uniform temperature of about 24° C. (75° F.), were 
all placed in the cars about 6 p. m. 
Accurate temperature records kept by Mr. V. W. Ridley showed 
that the most marked difference in the conditions to which the four 
boxes referred to in Table I were subjected was in the time consumed 
in reaching a temperature below 10° C. (50° F.). Examination of 
the fruit four days later, on arrival at destination, showed that the 
longer the time consumed in reaching 10° C, the greater the amount 
of rot developed. The results are summarized in Table I. 2 
Table I. — Relation of temperature to the growth of Rhizopus in inoculated strawberries 
of the Warfield variety , in connection ivith experimental shipments between Monett, Mo., 
and St. Paul, Minn. 
Hours con- 
Crate, reaching 10° C Condition on examination after arrival at destination. 
(50° F.). 
Berries practically all rotten, most of them bearing aerial hyphse with im- 
mature sporangia. 
All berries showing a rotten area about one-fourth of an inch in diameter 
around the inoculation. 
70 per cent of berries showing no indication of fungous growth, the remaining 
30 per cent showing small rotten spots. 
91 per cent of berries showing no indication of fungous growth, the remaining 
9 per cent showing very slight softening around the point of inoculation. 
Other boxes of inoculated fruit of the Warfield variety, as well as 
some Aromas, were also included in this experiment. The results 
1 Mr. E. L. Markell, of the Bureau of Markets, informs the writers that his own investigations, conducted 
during 1915 and 1916 at Hammond, La., the results of which are as yet unpublished, clearly showed the 
importance of care in handling strawberries. 
8 See also Ridley, V. W. Factors in transportation of strawberries from the Ozark region. U. S. Dept. 
Agr., Markets Doc. 8, 10 pp., 6 fig. 1918. 
