1916] 



PARASITIC RHIZOCTONIAS IN AMERICA 



313 



FIG. 8. STEMS OP MATURE BEAN PLANTS WHICH HAD BEEN PLACED IN A BENCH 



INFECTED WITH Rhizoctonia Solani ORIGINALLY OBTAINED FROM 



CARNATION PLANTS 



reddish brown band with a lighter colored, sunken area, and extend 

 thru the cortical layer into the woody tissues. As on the young seed- 

 lings, the spots are usually localized on one side of the stem, but in 

 some cases one lesion may girdle the plant. These lesions weaken the 

 stem and cause it to break off easily. 



The first account of Ehizoctonia causing a disease of bean was given 

 by Atkinson. 4 He reported that during the winter of 1894-95 it 

 caused damping-off of bean seedlings and attacked plants that were 

 from 6 to 10 inches high. He referred to this form as ''the sterile 

 fungus," and stated that its most characteristic peculiarity was the 

 mode of branching. 



In 1901 Duggar and Stewart 32 reported this fungus, from New 

 York, as the cause of a stem-rot disease of red kidney beans in the field 

 and of a damping-off among seedling beans in the greenhouse. 



