1916} PARASITIC EHIZOCTONIAS IN AMERICA 



325 



EGGPLANT, Solanum melongena 



During August, 1912, while some field observations were being 

 made on carnation stem rot, the fruits of a number of eggplants in 

 an adjoining field were found to be rotting at the point where they 

 touched the ground. The decay spread in all directions from this 

 point, making a sunken, brown area ; this was followed by the soften- 

 ing and subsequent collapse of the surrounding tissues. Fruits showing 

 this decay were brought into the laboratory and placed under a bell 

 jar. Around the diseased spot there soon developed a thick mass of 

 mycelium, which on microscopic observation was found to consist of 

 hyphae of Fusarium and Rhizoctonia. The decaying spots contained 

 no fungous threads, but were completely filled with bacteria. On plat- 

 ing, pure cultures of R. Solani were obtained. The cause of the pri- 

 mary infection is not known. It is very probable that both the Fusar- 

 ium and Rhizoctonia entered the tissues where the epidermis had been 

 destroyed. 



In July, 1913, the damping-off of a number of eggplant seedlings 

 in the vegetable greenhouses was noticed. This was shown, by pure 

 cultures of the diseased material, to be due entirely to Rhizoctonia. 

 The fungus produced the characteristic lesions on one side of the seed- 

 lings at the surface of the soil, causing the stem to break. 



Atkinson, 4 in his account of damping-off diseases, mentioned 

 eggplant seedlings among those susceptible to attacks of the sterile 

 fungus (Rhizoctonia). Rolfs 95 reported the presence of the Corticium 

 stage of Rhizoctonia on mature plants in an irrigated garden. Here 

 the plants affected drooped for a time and then wilted and died. Le- 

 sions were formed on the stems at the surface of the ground. 

 Wolf 140 - 141 in 1914 reported damping-off and a fruit rot of eggplants 

 due to Rhizoctonia (Corticium vagum B. & C.), but he does not re- 

 gard the fungus as the cause of serious injury to eggplants. 



FIVE-FINGER, Potentilla sp. 



A number of five-finger plants were found to be infected with 

 R. Solani during June, 1914, in inoculated sections in the floricul- 

 tural greenhouses. The mycelium of the fungus was present at the 

 nodes which touched the soil and also at the bases of the plants, where 

 crown rot was developing. 



FOXTAIL GRASS, Set aria glauca 



Several plants of foxtail grass growing under the same conditions 

 as the preceding host, five-finger, showed a root infection. 



Gypsopliila repens 



A number of GypsopMla repens plants were found diseased in the 

 herbaceous grounds during July, 1913. Pure cultures of the diseased 



