DISEASES OF PLANTS. 49 



llic more serious discnscs lo wliich uiiisciii; is subject. Of (liese the iiKtsL 

 destructive oue upon llie ahove-.m-nuud p;irts (d' the jihiid is the Alternaria 

 bliyht. Tills is due to an uudeteruiiued species of Alternaria, and it seriously 

 affects the leaves, stems, and all of the above-ground parts. It has been sho^A•n 

 that thorough spraying with Bordeaux mixture will entirely prevent this dis- 

 ease. Until recently the fungus on the wild plant was unknown, but during 

 the summer of 190G the author discovered it on ginseng plants growing wild in 

 the woods. 



Notes are also given on the soft rot of ginseng roots and a Rhizoctonia dis- 

 ease of the stems and roots. 



The blossom end rot of tomatoes, Elizabeth H. Smith (Mat^sachusctts >^t(i. 

 Tech. Bill. S, pp. ID, fiijs. 6). — Work on the tomato fruit rot was begun by the 

 author in the spring of 1002 and was continued for some time, the present pub- 

 lication giving the results of the investigations. 



The diseased condition of the fruit is readily recognized by the occurrence of 

 sjjots around or at one side of the style. The infected area is slightly sunken, 

 with a regular boundary, and clearly defined by a slightly raised ridge, beyond 

 which the tomato is healthy. The diseased tissues are dry and leathery, of a 

 light grayish-brown color, and on the larger spots rings of a darker color are 

 visible near the boundary. In longitudinal sections through the spots the inte- 

 rior boundaries are as clearly defined as the outer ones. 



A microscopical examination of the spots showed the presence of the fungus. 

 which upon cultivation proved to be Fiisarium soUiiii. This fungus is believed 

 to be the only active parasitic fungus connected with the fruit rot of tomatoes. 

 Species of Macrosporium, Cladosporium, and Alternaria have heen found in con- 

 nection with tomato rots, but the author was unable to induce anj' of these 

 fungi to grow upon green tomatoes. 



In connection with these studies, other diseases of tomatoes were investigated, 

 and a bacterial rot was studied in which the organism was isolated and infec- 

 tion induced by repeated inoculation experiments. One type of the bacterial 

 rot <leveloped characters which were indistinguishable from the characteristic 

 blossom end rot (hie to Fusariinn. 



An apple rot due to Volutella, F. L. Stevens and .T. G. Hall (Jour. MijcoJ.. 

 13 (1907), Xo. .S9, pp. 9Jf-99, pi. 1). — A black rot of ai)ples closely imitating in 

 appearance that caused by Spha^ropsis is described, which is said to have been 

 observed in various sections of North Carolina. 



In general the disease may be recognized by the occurrence of black rotten 

 spots upon the fruit. The central and older portions of the decayed region are 

 of an intense coal-black color, while the younger portion of the spots is Itrownish. 

 A close inspection reveals the presence of slightly elevated ])imple-like places 

 on the cuticle. These become larger and more i)roiiouiiced as the center of the 

 spot is approached. On sectioning an apple through one of these areas the 

 more recently attacked tissues will be found of a brownish color, while the 

 older portions are black. While the decayed portions are softer than the 

 healthy ones, the disease can in no sense be considered a wet rot, the softness 

 being due to a sjiongy dryness rather than to a watery dissolution. 



The organism causing the disease has been isolated and cultivated on various 

 media, Init in no case were spores formed on artificial media. When grown 

 on sterilized apple twigs, however, spores were formed in great abundance. 

 Inoculations made from mycelium grown in pure cultures developed the charac- 

 teristic spots in a few days where the skin of the apple had be^en injured by 

 pricking, but all attemjits to secure inoculations through the unbroken cuticle 

 were without success. 



