Apr., 1922] 
STEVENS ROTS OF EARLY STRAWBERRIES 
211 
relation of these two fungi on early strawberries, conditions are much like 
those in refiigerator cars (10, p. 10). That is, temperatures are common 
under which Botrytis cinerea is able to develop readily while the growth of 
Rhizopus nigricans and of fungi with similar temperature requirements is 
largely inhibited. This partial freedom from competition enables Botrytis 
cinerea to occupy in California a much more important place as a fruit rot 
of strawberries than in the southeastern United States. 
Summary 
Rhizopus nigricans, known to be the most common cause of decay of 
ripe strawberry fruits in Florida, is of minor importance on winter straw- 
berries in California. 
Botrytis cinerea, which is common on strawberries only under conditions 
of extreme moisture in Florida, is regularly abundant in California during 
the winter. 
This difference seems to be due in part to the somewhat more favorable 
moisture conditions in California, but especially to the fact that during the 
winter months there is a daily period during which the temperature is 
favorable for the growth of Botrytis cinerea, but unfavorable for the growth 
of Rhizopus nigricans. 
Bureau of Plant Industry, 
Washington, D.C. 
LITERATURE CITED 
1. Ames, Adeline. The temperature relations of some fungi causing storage rots. Phyto- 
path. 5: 11-19. 1915. 
2. Bennett, W. J. Diurnal variations in humidity. Mo. Weather Rev. 47: 466-468, 
2 fig. 1919. 
2a. . Humidity and vapor pressure at Tampa, Fla. Mo. Weather Rev. 47: 710. 
1919. 
3. Brooks, C, and Cooley, J. S. Temperature relations of apple-rot fungi. Jour. Agr. 
Res. 8: 139-164- 3 pl-, 25 fig. 1917. 
4- . Temperature relations of stone-fruit fungi. Jour. Agr. Res. 22: 451-465, 
1921. [1922.] 
5. Darrow, G. M. Strawberry culture: South Atlantic and Gulf coast regions. U, S. 
Dept. Agr. Farmers' Bull. 1026. 40 p. 21 fig. 1919. 
5. . Strawberry culture: Western United States. U. S. Dept. Agr. Farmers' Bull. 
IQ27. 29 p. 16 fig. 1919. 
7. Fawcett, H. S. Citrus diseases of Florida and Cuba compared with those of California, 
Cal. Agr. Exp. Sta. Bull. 262: 153-211. 24 fig. 1915. 
8. Hanzawa, J. Studien iiber einige Rhizopus- Arten. Mycol. Centralbl. 5: 230-246 
257-281. 12 fig. 1914, 1915. 
I). Stevens, N. E., and Wilcox, R. B. Rhizopus rot of strawberries in transit. U. S. 
Dept. Agr. Bull. 531. 22 pp. i fig. 1917. 
10- . Further studies of the rots of strawberry fruits. U. S. Dept. Agr, Bull, 
686. 14 pp. 1918. 
11- . Temperatures of small fruits when picked. Plant World 21 : 176-183, 1918. 
