Apr. IS. 191S Phoma Destructiva 



A laboratory experiment was also tried under thermostatic conditions 

 of temperature and moisture. Green tomatoes picked from plants grow- 

 ing in a garden plot near the pathological greenhouses were thoroughly 

 washed in water, soaked in a 2 per cent formaldehyde solution for three 

 hours, after which needle-prick inoculations were made (Aug. i, 1914) 

 from a 6-weeks-old culture of the Phoma fungus. The inoculated to- 

 matoes were then wrapped separately in paraffin paper and placed in 

 zinc boxes in different compartments of an incubator. Water in a lower 

 tray kept the air saturated. Temperature records were taken each day 

 and averaged for the period during which the experiment lasted. Unin- 

 oculated tomatoes were used as checks. At the end of 18 days the 

 tomatoes kept at an average temperature of 6.6° C. showed no decay 

 and only a slight discoloration of tissue about the needle pricks, while 

 tomatoes kept at 19.7° C. showed decayed spots in every case. Within 

 the tissue of these spots, measuring 2 to 4 cm. in diameter, pycnidia and 

 spores of the Phoma were found in abundance. 



INFECTION OF TOMATO PL,ANTS IN THE FIELD 



On June 10, 191 4, six tomato plants (Matchless variety) growing in 

 garden plots at Arlington Farm were sprayed with a spore suspension 

 of the Phoma fungus made from a corn-meal culture. On August 15 the 

 plants were examined and a few spotted leaves picked and brought to 

 the laboratory. Pycnidia and spores of a Phoma were found in tissue 

 cut from the spots. A month later the plants were again examined, and 

 the leaves, stem, and fruit were found to be afifected. Material was 

 collected and brought in for microscopical study. The brown discolored 

 patches on the leaves had a grayish center, upon the surface of which 

 scattered pycnidia could be seen. From these small brown pycnidia 

 spores issued in coils. Within the discolored tissue of the petiole and 

 stem similar pycnidia and spores were found. The spotting of the fruit 

 was characteristic, and here, too, the Phoma fungus was found. 



Experiments were also made on August 27, 1914, with six tomato 

 plants of the Livingston Coreless variety. A spore suspension of the 

 Phoma was used and the fruit was needle-pricked after spraying. On 

 September 10 fruit spots were observed upon green, partly ripened, and 

 fully ripened fruit. By means of agar plates the fungus was reisolated 

 from fruit and stem tissue. 



CROSS-INOCULATIONS BETWEEN TOMATO FRUIT AND LEAF 



The foliage of young and nearly mature tomato plants was sprayed 

 with a fungous suspension of the Phoma made from cultures isolated 

 from diseased tomato fruit tissue. Diseased spots were produced in four 

 to six days, and the fungus was recovered from the leaf tissue by means 

 of agar plates. With cultures thus obtained needle-prick inoculations 

 were made into green and ripening fruit (greenhouse plants), and the 

 characteristic Phoma spotting was again produced. 



