PEACH SCAB AND ITS CONTEOL. 27 



each source of infection, while six, similarly treated but not inoculated served as 

 controls. On June 6 this experiment was duplicated. 



Results from, series inoculated on May 29. — Two fruits inoculated with the fruit strain 

 of Cladosporium carpophilum, two inoculated with the twig strain, and one control fell 

 prematm'ely. On Sunday, August 2, before final results were available, the remaining 

 fruits of this and the succeeding series, in spite of notices and experimental labels, fell 

 victims to the gastronomic proclivities of tresjiassers. The earlier results, however, 

 were sufficient to be of material value. 



On one of the fi'uits inoculated with the twig strain of the fungus, eight scab lesions 

 were barely visible on August 1, though no macroscopic infection could be observed 

 on July 25. 



On one of the fruits inoculated with the fruit strain, very early macroscopic stages of 

 infection were observed on Jxily 25, while 16 definite lesions were evident on August 1. 



The remaining inoculated areas bore no definite macroscopic lesions on August 1, 

 though their appearance strongly suggested the presence of abundant infection in 

 incipient stages. 



No evidence of the disease was observed upon any controls or uninoculated fruits, 

 lesions appearing only on inoculated areas. 



Results from series inoculated on June 6. — On July 25 no infection was evident. On 

 August 1 scab lesions were discernible on one of the fruits inoculated with the twig 

 strain of the fungus, while the appearance of the inoculated areas generally suggested 

 the presence of incipient infection. The controls showed no evidence of infection. 



REISOLATION OF THE FUNGUS. 



Thorough microscopic examinations showed that Cladosporium 

 carpopliilum was miiformly associated with the lesions induced by- 

 inoculation. The fungus was reisolated by the poured-plate method 

 and foimd to possess the typical morphological and cultural characters 

 of C. carpopliilum. 



CONCLUSIONS. 



These experiments show (1) that Cladosporium carpophilum from 

 pure cultures of single-spore strains isolated from scab lesions on 

 peach twigs or fruit is capable of causing typical and abundant 

 infection upon peach fruit; (2) that, in Hke manner, this fungus taken 

 directly from twig lesions is capable of producing the disease upon 

 the fruit; (3) that the period of incubation of the fungus upon the 

 fruit may vary from 42 to 77 days, very early niacroscopic evidences 

 of the disease sometimes appearing within a shghtly shorter period; 

 (4) that the presence of the nutritive solution used apparently 

 hindered infection; and (5) that, under the conditions of these experi- 

 ments, the three superficial fungi tested are not pathogenic to peach 



fruit. 



Twig and Leaf Inoculations. 



Preliminary experiments made in 1913 showed clearly that under 

 field conditions where the disease is prevalent, the chief difficulties 

 attending twig and leaf as well as fruit inoculations are (1) the abun- 

 dance of natural infection and (2) the difficulty of securing at will 

 conditions favorable for infection. These obstacles were satisfac- 



