2 Journal of Agricultural Research voi. iv. no. i 



Macrosporium were observed. Since, however, the pycnidial fungus, 

 whose general appearance indicated that it belonged to the genus Phoma, 

 was found in such abundance in tissue from all of the spots examined, 

 it seemed probable that this fungus might prove to be the primary cause 

 of this tomato fruit-rot. An isolation of this fungus from diseased tissue 

 was therefore undertaken, 



ISOLATION OF THE FUNGUS FROM DISEASED TOMATO FRUIT 



With sterilized instruments small pieces of diseased tissue, partially 

 sterilized in a solution of mercuric chlorid (i to i,ooo), were cut out 

 from beneath the surface of several of the spots and transferred to cul- 

 tural media. A grayish white mycelial growth developed on string-bean 

 agar, and at the end of two weeks small dark pycnidia similar to those 

 found on the tomato fruit were observed. Under the microscope numer- 

 ous hyaline i -celled vacuolated spores could be seen issuing from the 

 crushed pycnidia. Some of these spores were transferred to sterilized 

 potato cylinders, cotton and tomato stems, lima-bean, prune, and string- 

 bean agars, and from these transfers pure cultures of the Phoma fungus 

 were obtained and later used in inoculation experiments. Pycnidia and 

 spores were produced in abundance on potato cylinders, tomato stems, 

 and upon Hma-bean and prune-agar slants. 



Nearly two years after the receipt of the Cutler specimens some dis- 

 eased tomatoes affected with a similar spotting were sent in (February, 

 1914) by A. F. Young & Co., New York City. These tomatoes were 

 selected from shipments received from Cuba (PI. Ill, fig. i) and from 

 Punta Gorda, Fla. By the usual agar plate methods a Phoma fungus, 

 identical with that isolated from the Cutler fruit, was obtained from 

 tissue cut from spots occurring upon specimens from both Cuba and 



Florida. 



INOCULATION EXPERIMENTS 



INFECTION OF GREEN AND RIPE FRUIT IN THE GREENHOUSE 



Inoculation experiments were begun on March 30, 191 2, with some 

 large tomato plants growing in the greenhouse. Needle-prick inocu- 

 lations were made into green and ripening fruit, and also into the stems 

 and leaves of these plants, the Phoma fungus being transferred from 

 20-day-old cultures of string-bean agar. Plants having fruit, stem, 

 and leaves pricked with a sterilized needle were used as controls. In 

 four to six days spots developed on green and ripe tomatoes, occurring 

 upon the sides, stem end, and blossom end of the fruit, according to 

 the position of the inoculation pricks. The spots thus produced by 

 inoculation of the fungus were similar in appearance to those observed 

 upon the diseased specimens from Florida. A week after inoculation 

 the stem tissue of the tomato plant was seen to be slightly discolored 

 about the needle pricks. This discoloration, however, had not spread 

 to any considerable extent, and the surrounding tissue still remained 



