Apr. IS. 191S Phonia Destructiva 



firm. Cross sections of a stem cut through the point of inoculation 

 showed a brownish area, with mycelium in the epidermal and outer 

 vascular tissue. On the leaves no evidence of spotting was observed 

 two to four weeks after inoculation.^ At the end of two weeks the 

 spots produced on the fruit by inoculation had spread considerably 

 beyond the needle pricks, and the tissue had perceptibly darkened. 

 The ripe tomatoes were beginning to fall from the vines. Some of 

 these inoculated specimens were brought to the laboratory for exami- 

 nation. The almost black spots, measuring 2 to 3.5 cm. in diameter 

 on the ripe fruit, were surrounded by a lighter zone the tissue of which 

 was soft and somewhat sunken, while that of the central portion of the 

 spot was black and crustlike. Tissue from the discolored areas was 

 examined and found to be full of fungus mycelium, while on the surface 

 of the crustlike portion numerous dark pycnidia could be seen. The 

 hyaline to brownish hyphae were septate and branched, and the dark 

 spherical pycnidia contained masses of i -celled hyaline spores which 

 issued in coils from a central pore. A microscopic study of this fungus, 

 made from diseased tissue taken from inoculated fruit spots, showed it 

 to be the same as that used in the inoculation and previously isolated 

 from the Cutler material. 



The spots produced on the green fruit two weeks after inoculation 

 were not as large as those of the ripe tomatoes, measuring only i to 

 1.5 cm. in diameter, and the discoloration presented a somewhat differ- 

 ent appearance. The central portion of the spot on the green fruit 

 was of lighter color, becoming darker toward the circumference and 

 merging into a definite dark-brown border. 



A second inoculation experiment with greenhouse tomato plants was 

 begun on April 17, 1912, when green and partly ripened fruits were 

 inoculated by means of needle pricks with fungus from 22 -day-old 

 tomato-stem cultures. Two weeks after inoculation conspicuous dark 

 diseased areas had developed, similar in appearance to the spots pro- 

 duced by the previous inoculation and to those of the diseased Florida 

 tomatoes. Examination of the darkened tissue showed mycelium, 

 pycnidia, and spores of the fungus inoculated. 



An interruption of the work occurred at this time, and further study 

 of this tomato fruit rot was not resumed until the spring of 191 3. Cul- 

 tures of the Phoma fungus were kept growing upon different kinds of 

 media, transfers being made every 8 to 10 weeks. In February, 191 3, 

 the work was resumed. Questions as to how early the fungus is able 

 to infect the fruit and the means by which it gains entrance to the tissue 

 suggested themselves, and experiments in greenhouse and laboratory 

 were begun in order to determine something definite in regard to these 

 points. 



1 l,ater experiments proved the fungus to be parasitic under certain conditions of moisture and tempera- 

 ture upon both leaves and stems of the tomato. Failure to produce the disease in the early experiments is 

 believed to have been due to the low humidity and temperature of the atmosphere of the greenhouse. 



