368 Journal of Agricultural Research voi. xxii. no. 7 



Of course the final test of identity would lie in whether or not the as- 

 cogenous stages of the two fungi, assuming them to exist, would prove 

 to be identical. 



Specimens of Phyllostica congesia on fruit and foliage of Prunus 

 triflora have been deposited in the Pathological Herbarium, Bureau of 

 Plant Industry, United States Department of Agriculture. 



It is not known how the fungus is carried over from one season to 

 another. If it occurs on the twigs, as the writer is inclined to think, there 

 would be good reason for believing that production of spores from twig 

 lesions in the spring would constitute an important infection source. It 

 is also possible that the fungus survives the winter on leaves and fruit. 



On all the ordinary culture media the fungus shows about the same 

 type of growth. On corn meal agar, beef agar, prune agar, potato agar, 

 and oatmeal agar growth is very slow, and on all these media it presents the 

 same appearance. There is a dense black mass of closely woven hyphae 

 forming a raised and irregular aggregation of shining bead-like bodies 

 which may be considered as sterile pycnidia, since they are more or 

 less hollow bodies containing oil drops. The margin of the growth is 

 often fringed; in fact on the above-named media the growth is almost 

 as blotch-like as it is on the fruit of the plum. On sterihzed stems of 

 Melilotus the growth resembles that on the agars, but spores are often 

 formed though very scantily. 



On Japanese plum twigs growth is also very slow. Pycnidia and 

 spores are formed in about two months. Pycnidia are formed on the 

 bark and may also be formed at the cut end of the twig, in which case 

 they are densely aggregated. 



Sterilized apple twigs proved to be the best medium for the production 

 of spores, though two to three months must elapse before spore produc- 

 tion begins. On this medium the only sign of growth by the fungus is 

 the formation of a dense mass of hyphae and pycnidia, closely aggregated 

 at the upper end or at an abraided place on the side of the twig. On all 

 the media used the type of growth exhibited by Phyllosticta congesia 

 differs somewhat from that of P. solitaria. On sterile apple twigs, for 

 instance, the latter produces pycnidia which are scattered over the bark, 

 whereas the pycnidia of the former are formed only at the cut ends of 

 the twigs. 



In 191 7 the fungus was isolated from both fruit and leaves by the 

 poured plate method, using spores, and by planting bits of the diseased 

 tissues in plates. 



In the spring of 19 18, no spores had been obtained in cultures, but 

 inoculations were made by spraying the young fruits and leaves of 

 Abundance and Burbank plums with bits of hyphae and sterile pycnidia 

 suspended in sterile distilled water. The results were negative in every 

 case. 



