264 Early Studies in Bacterial Plant Diseases 



are much the same as in the germ disease, [cucurbit wilt} i. e., sudden 

 wilt and drying up of long shoots or whole vines. This comes about in the 

 same way too, i. e., by the mechanical clogging of the vessels. This I have 

 found most abundant in the stem near the root but also abundant in the 

 root itself and in many stem vessels 2 to 5 feet away from the root. At this 

 stage the injurious action seems to be chiefly mechanical but as the vine 

 begins to die the fundamental tissues are invaded. The fungus produces 

 colorless conidia in the vessels, and there is a pycnidial fruit occurring on 

 stem and petiole but I have not yet examined this closely enough to be 

 certain whether it is part of the life cycle. My belief is that the fungus 

 winters over in the dead vines. I am now looking for other spore forms in 

 trying to determine how it enters the plant. Think I have found the place 

 of entrance but am not sure and will not say anymore about it for the 

 present. 



Two days later, believing that while there he could isolate the 

 fungus, he sent for litmus paper, more agar tubes, and sterile 

 petri dishes. Galloway remembered a bulletin by Atkinson on a 

 cotton disease which seemed similar and sent a copy. But before 

 the materials arrived, Smith had succeeded in growing the fungus 

 in agar and had pure cultures from single spores three days old; 

 he also had six tube cultures made by cutting out small segments 

 of infected stems. 



For years, whenever he encountered a multiplicity of organisms 

 in his cultures. Smith had been skeptical of the value of his results. 

 In 1891 especially, when in Georgia preparing field cultures of 

 peach rosette in a make-shift laboratory, he had been conscious of 

 possible air contaminations and the wisdom of scrupulous care 

 and cleanly work. He, therefore, would not assure Galloway that 

 each of his field cultures made in South Carolina were " entirely 

 pure." Nor would he assure Galloway that in details his water- 

 melon Fusarium agreed with Atkinson's cotton disease organism 

 but admitted it might be the same. " Spores are larger in this 

 form and symptoms different," Smith wrote. But with the cultures 

 he possessed he " studied the growth from single spores (in agar) 

 round to the time when they have fruited again (less than twenty 

 four hours), and have some good camera drawings," he informed 

 on July 8. 



This week I hope to start infection experiments with pure cultures but 

 there is so much of the disease here that these will have to be made on a 

 large scale to establish anything. Can you not have some watermelons 

 started at once in one of the Department greenhouses, preferably the 



