lO 



Fig 4. Conidial spore formation in stem rot Fusarium. 



This disease is entirely similar in its general aspects to those 

 described by Erwin F. Smith on Melons, Cowpeas, etc., by Masse on 

 Tomato, and others of the same class, caused by forms of Fusarium. The 

 present species or form appears, so far as studied, to have very little ten- 

 dency toward spore formation. Young affected plants placed in a moist 

 chamber soon become overrun with a white mycelium upon the shorter 

 branches of which lunulate Fusarium conidia develop in abundance. The 

 production of such conidia or of any other spore form, has never been 

 observed upon affected plants in any stage of the disease, though carefully 

 looked for in a large amount of material. Cultures on potato and prune 

 juice from affected tissue give mostly white sterile mycelium with occasion- 

 ally a few conidia. A similar growth is also produced in a great many 

 cases from affected plants in the moist chamber. Infection takes place 

 readily in seedlings started in earth in which affected tissue has been 

 buried. At the same time it is to be noted that in our thoroughly infested 

 house, plants started in sterilized earth were quite as badly affected as those 

 in ordinary soil, and by the same Fusarium fungus. Apparently, therefore, 

 conidial infection of seedlings occurs. Further experiments are now going 

 on in regard to the mode of infection, but a long series of observations has 

 left no doubt that the disease is contracted in the seed bed and that plants 

 which are healthy when set out in the permanent bed are thereafter 

 immune, even in infected soil. 



