VI. JONES' SOFT ROT OF CARROT, ETC. 



Type. — This is a rapid bacterial wet-rot of storage paren- 

 chyma (roots, rhizomes, fruits and fleshy stems). It seldom 

 attacks well-developed green parts, nor does it develop vigor- 

 ously in storage tissues unless they are turgid. It was described 

 in 1901 by Prof. L. R. Jones from carrot roots grown in Vermont, 

 but he obtained it on the fleshy parts of many other plants by 

 pure-culture inoculation, and it is now known to be widespread 

 in nature on a variety of hosts. Probably it occurs all over the 

 world but its geographical distribution remains to be worked 

 out. 



We owe most of our knowledge of this disease to Prof. 

 Jones, but others have also studied it critically in recent years, 

 notably, Harding and Morse, and to some extent also the author 

 of this book. 



Since the appearance of Jones' first paper the same organism 

 has been isolated from soft rots on other plants by several plant 

 pathologists, who have studied and described it under other 

 names. Furthermore, several other very closely related if not 

 exactly identical soft-rot organisms have been discovered, de- 

 scribed and named. M. C. Potter's white rot of turnips is due 

 to this organism, and his paper appeared in 1899 (two years earlier 

 than Jones' paper) , but he described as its cause a polar flagellate 

 organism and his name, therefore, cannot be substituted. 



The parasitic action of all of these morphologically and cul- 

 turally similar soft-rot schizomycetes is essentially the same and 

 Harding and Morse beheve all of them to be one species but I 

 am not entirely committed to this belief. They enter the plant 

 through wounds and rapidly disintegrate the susceptible parts 

 into a soft, wet pulp (Figs. 164 to 166), having first poisoned the 

 tissues by means of their by-products. They advance into the 

 weakened tissues by way of the intercellular spaces and separate 



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