26 BULLETIISr 395, U, S. DEPARTMENT OF AGRICULTURE. 



SUMMARIZED EEPORT OF ELBERTA INOCULATIONS. 



A brief summarized report of the Elberta fruit inoculations is given 

 below (PI. V, figs. 1 to5). 



Sources of inoculation. — Cladosporium carpophilum from cultures and directly from 

 abundantly sporulating lesions on peach twigs, and undetermined fungus A, unde- 

 termined fungus B, and Dematium sp. from cultures. Only young, vigorously sporu- 

 lating Lima-bean agar slant cultures of single-spore strains isolated from peach twigs 

 were used. 



Methods. — Fruits bagged on May 8 were inoculated by the methods previously 

 described in four series on May 16, May 20, May 27, and June 6, respectively, and the 

 inoculated areas kept intermittently moist until maturity. 



Results. — In a few cases the experimental fruits were shed or were lost by accidental 

 mechanical injury, wMle in a few of the earlier direct inoculations the spores used 

 failed to germinate. These inoculations are not included in this summary. 



On 16 areas inoculated with undetermined fungus A, 16 with undetermined fungus 

 B, and 16 with Dematium sp. no infection resulted. Consequently, these inoculations 

 may be considered as supplementary controls. 



On the 100 control areas of the four series, including as controls the 48 inoculations 

 with the superficial fungi mentioned in the preceding paragraph, not one scab infec- 

 tion developed. Upon the entire protected surfaces of the 50 fruits in question only 

 one lesion appeared, this being in all probability the result of a chance infection 

 subsequent to the time of inoculation. Upon these 50 fruits the total number of 

 infections was only 21, while 35 matured without showing any e^ddence of the disease. 



On the 18 areas inoculated with Cladosporium carpophilum from pm'e cultures, 707 

 typical infections appeared, an average of 39 lesions on each inoculated area. Only 

 one of the 18 inoculations failed to result in definite and satisfactory infection, this 

 being undoubtedly due to some local imperfection in the conditions of the experiment. 

 In only two cases did the disease develop on uninoculated areas, sparse infection 

 occurring in both instances near the peduncles, well away from the inoculated siufaces. 



On the six areas directly inoculated with Cladosporium carpophilum from twig 

 lesions, 63 typical lesions developed, every inoculation producing decisive infection. 

 Only one lesion appeared upon the uninoculated areas of the fom* peaches in question. 

 As these inoculations were made in two corroborative series and as four of them were 

 situated upon the protected equatorial sinfaces of the fruits, they were doubly guarded 

 against natural infection and thoroughly justify positive conclusions. 



CONFIRMATORY EXPERIMENTS OF 1914. 



Experiments conducted at Madison, Wis., in 1914 were planned (1) 

 to confirm the results of the preceding season in a locality where peach 

 scab has not been observed to occur naturally and (2) to determine 

 whether infection may occur during the early stages of development 

 of the fruit. The report of these experiments is summarized as 

 follows : 



Sources of inoculation. — Abundantly sporulating young Lima-bean agar cultures of 

 single-spore strains of Cladosporium carpophilum isolated from scab lesions of (a) fruit, 

 (6) twig, and (c) leaf of the peach. 



Methods. — On May 29, about a week after the shedding of the calyces, young Carman 

 fruits about 8 mm. in diameter were inoculated, the methods of the Elberta inocula- 

 tions of the preceding season being used throughout. The areas of inoculation and 

 control were kept intermittently moist until June 23, when the bags and the moisture 

 apparatus were removed and the fruits left free. Foiu" fruits were inoculated from 



