Apr. IS. 1915 



Phoma Destructiva 



Four weeks after inoculation the tomatoes which had been exposed 

 without injury to the spraying of the spore suspension in the foregoing 

 experiment were picked and placed in moist chambers in the laboratory. 

 This was done in order to see whether infection would occur on the 

 sprayed fruit when separated from the vine. At the end of 12 days the 

 tissue of these tomatoes remained firm and there was no evidence of 

 infection. 



Fully grown tomato plants bearing green and ripening fruit were used 

 in another experiment in order to show the effect of fungous inoculations 

 by the wounding and nonwounding of nearly mature tomatoes. Trans- 

 fers with a platinum loop were made from tomato-stem cultures of the 

 Phoma fungus, to blossom end, stem end, and sides of green and ripen- 

 ing fruit. Some of the tomatoes were needle-pricked and some were not 

 injured. Control plants were also used. The observations given in Table 

 II were made 5 and 10 days after inoculation. 



Table II. 



-Results of the inoculation of maturing tomato fruit with Phoma fungus 

 (greenhouse experiment) 



As a result of inoculations into young and maturing tomato fruits, it 

 may be seen from data in Tables I and II that infection begins soon after 

 the fruit sets, a slight discoloration or definite spotting developing within 

 five to seven days, according to the method of inoculation used. It is 

 also apparent that the fungus is a wound parasite, since no infection 

 occurred where the epidermis of the fruit remained unbroken. Wound- 

 ing of the fruit by insects, bruising, and natural cracking of the tissues 

 no doubt affords a common means of entrance for this parasite. 



In the inoculation work it was noticed that the discoloration of the tis- 

 sue developed rapidly upon ripening tomatoes, the spots measuring i to 

 3 cm. in 10 days, while those upon the green fruit were only about one- 

 fifth as large in the same length of time. The discolored tissue of the ripe 

 fruit varied from brown at the circumference to almost black in the 

 central portion, the whole being bordered by a zone of watery-looking 

 tissue. In the green fruit a lighter central area became surrounded by 

 a darker band, and the watery zone was not noticeable. Numerous 

 pycnidia developed upon the darkest tissue, giving the surface a pimply 

 appearance. 



