14 



Journal of Agricultural Research 



Vol. IV, No. I 



Pycnidia from cultural media and from tomato fruit were measured, 

 with the following results: 



Corn-meal culture. Average of lo pycnidia, 151/1, variation 107 to 174/z. 

 Beef-agar culture. Average of 10 pycnidia, 103//, variation 59 to 2iiju. 

 Tomato fruit. Average of 40 pycnidia, 139/*, variation 53 to 348/i. 



From these measurements it will be seen that an average of 60 measure- 

 ments gives a diameter of i3ij«, with a variation ranging from about 

 50 to 350/i. 



PYCNOSPORES 



Only one kind of spore is produced in the pycnidium, the hyaline 

 I -celled pycnospore. These spores are continuous, 2-guttulate, sub- 

 cylindrical to subglobose in shape, with blunt, rarely tapering ends, and 

 are produced singly on the unbranched filiform basidia which arise from 

 the inner hyaline cells of the pycnidial wall. 



No definite stroma is formed and no perithecial stage has been 

 observed either in culture or upon the host tissue. 



Pycnospores were found to vary considerably in size. The following 

 measurements (Table IV) were made of spores grown upon media favor- 

 able to their development. 



Table IV. — Variation in size of pycnospores of the Phoma fungus 



The average size of 140 pycnospores is found from these measurements 

 to be 4.7 by 2.3/i, with a variation of 3 to 8.5 by 1.7 to 3.7//. 



CULTURAL CHARACTERISTICS OF THE FUNGUS 



The fungus grows well on all of the media commonly used in culture, 

 good spore development being obtained on com meal, string-bean agar, 

 oat agar, potato cylinders, and tomato stems. Cultural characteristics 

 of the fungus upon a number of different kinds of media are here given. 



Beef agar. — Fungous colonies appear on beef agar (+15) plates 

 within two to three days. These colonies, varying in size from pin 

 points to 5 mm. in diameter, are round, whitish, and somewhat cottony 

 in appearance. The hyphse branch freely, radiating toward the circum- 

 ference of the colony. Beef agar is not favorable for spore develop- 

 ment, although pycnidia and spores are sometimes produced. 



