[Vol. 2 



436 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



strange, therefore, if somewhat similar effects should charac- 

 terize, as they do, purely "physiological" disturbances. Stem 

 lesions are generally dark, sunken areas, clearly different from 

 black leg, occurring at the surface of the ground or on any of 

 the underground stems, or tuber-forming stolons. These 

 lesions may result in the early death of the affected plants. 

 Selby ('02, '03) maintains that generally the lesions upon 

 young shoots are associated with stunted growth and the pro- 

 duction of rosette-like clusters of the upper leaves, as well as 

 with less marked modifications of habit, including slight leaf 

 rolling. Drayton ('15) finds the hyphae in the lesions. 



If the tuber-bearing stolons are the seat of injury, the food 

 supply is cut off from the young tubers and there may result 

 "little potato," a form of the disease which Rolfs ('04) has 

 found to be an important cause of the potato failures in 

 Colorado. Little potato in Australia is considered an evi- 

 dence of underground injuries occurring late in the season. 

 Injuries which effectually girdle the stem, especially if these 

 occur during a moist season or when the crop is frequently 

 irrigated, lead to the formation of aerial tubers. In the re- 

 lation of Rliizoctonia to the various types of potato diseases 

 much remains to be investigated, and Orton ('14) rightly 



jsts that inadequate attention has been bestowed upon 

 the question of the predisposition of the tubers used as seed, 

 since it is quite possible that these may yield offspring with 

 tendencies toward resetting, leaf rolling, and other morpho- 

 logical modifications. 



?->?-> 



ROT OF FLESHY ROOTS 



The root rot of beet, apparently first described by Eidam 

 ('87) in Germany, and shortly afterward found by Pammel 

 ('91) in Iowa, was observed in New York (Duggar, '99) some 

 years later. Since that time it has appeared epidemically 

 in Nebraska (Lvon and AVianco, '02) and other western states. 



The fungus is most virulent during midsummer or later. In- 

 fection may take place at the bases of the leaves or on the 

 fleshy root. The leaf bases blacken, the leaves become paler, 

 and finally wilt. Pammel ('91) has drawn attention to the 



