DRNAL OF AGEICrailML ffiSEARi 



Vol.. XXII Washington, D. C, November 26, 1921 No. 9 



TEMPERATURE RELATIONS OF STONE FRUIT FUNGI 



By Charles Brooks and J. S. CoolEY, Pathologists, Fruit Disease Investigations , 

 Bureau of Plant Industry, United States Department of Agriculture 



The two fungi that cause the heaviest market losses on peaches and 

 other stone fruits are Sclerotinia cinerea (Bon.) Wor. and Rhizopus 

 nigricans Ehr. The former is often referred to under its conidial name 

 of Monilia and is the cause of brown rot, while the latter is the cause of 

 black mold rot. 



The present paper gives the results of investigations in regard to the 

 temperature responses of these two fungi under various conditions of 

 growth. 



In all the experiments except that reported in figure i the spores 

 were inoculated into the fruit from pure cultures. Except where other- 

 wise stated the cultures were obtained from the host into which the 

 inoculations were made. The fruit was warm when inoculated but after 

 inoculation was placed in moist chambers and stored at once at the 

 temperature indicated. Five or more peaches or prunes were used at 

 each temperature in each test. The fruit was at the proper maturity for 

 picking and shipping and was carefully selected for quality and sound- 

 ness. In dividing the fruit into lots for distribution at the various 

 temperatures uniformity was secured by selecting seven peaches or 

 prunes (or as many as there were temperatures) that were similar in size, 

 color and degree of maturity and distributing these one each in seven 

 moist chambers and repeating the process till the desired amount of fruit 

 was obtained. 



Records were made of the diameters of the rots at intervals of one or 

 two days, and the average of all the rots at a given temperature on a 

 particular date was taken as a basis for plotting the curves in the accom- 

 panying figures. The equipment used in securing the various tempera- 

 tures has been described in an earlier publication.^ 



SWEET CHERRIES 



In 19 19 a temperature experiment was made on Governor Wood 

 cherries. These had been shipped by express from Wallingford, Conn., 

 to Washington, D. C, and arrived somewhat bruised and with considera- 

 ble brown rot. The specked and rotten cherries were discarded, but the 

 slightly bruised ones were included in the experiment. The cherries 

 were divided into five equal lots and distributed without inoculation at 



' Brooks, Charles, and Cooley, J. S. temperature relations of applb-ROT fungi. In Jour. Agr. 

 Research, v. 8, no. 4, p. 139-164, as fig., pi- 1-3- 1917- 



Journal of Agriculture Research, Vol. XXII, No. 9 



Washington, D. C. Nov. a6, 1921 



aap Key No. 0-256 



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