120 Report op the Botanist of thhj 



parasitism op the pungus. 



In many cases RMzoctonia is truly parasitic, and there can be 

 no question about its being the cause of the diseases with which 

 it is associated. The diseases of beet, carnation, lettuce, and 

 some others with which we have experimented may be readily 

 induced by merely placing in contact with the plant pure cultures 

 of the fungus; and in time infection will result, provided there 

 i« sufficient moisture. Infection results more readily with the 

 carnation by direct insertion of bite of the fungus into the plant. 

 In other cases where the fungus is associated with disease, we 

 have as yet no proof that RMzoctonia is the chief or even partial 

 cause of the trouble. It may sometimes be associated with other 

 fungi, perhaps Fusarium. Atkinson^ has indicated that the 

 sterile damping-off fungus of cotton may perhaps have a part to 

 play in the Fusarium disease of cotton, at least in initiating the 

 disease. 



In spite of the fact that RMzoctonia is at times an effective 

 parasite, the fungus is probably capable of protracted existence 

 upon decaying organic matter in the soil. In this way it may 

 be able to propagate itself, and to spread from plant to plant in 

 the soil even when culture or other means fail to disseminata it. 

 In fact, it seems to be of very general occurrence in the soil, and 

 is likely to be quite commonly found in propagating beds as a 

 cause of damping-off among cuttings and seedlings. From our 

 experience thus far, we venture to predict that few forms of this 

 fungus will be found very selective as to host, and one may well 

 search for it upon the common weeds. The occurrence of this 

 fungus as a disease producing organism is largely dependent upon 

 the conditions, and when by excess of moisture or of heat the 

 plant is placed at a disadvantage, or the fungus favored, the dis- 

 ease is likely to occur. 



* Atkinson, Geo. F.: Some Diseases of Cotton. Ala. Agr. Exp. Sta., Bul- 

 letin 41, p. 28. 



