PARASITIC KHIZOCTONIAS IN AMERICA 321 



found to have a brown mycelium and many small sclerotia between the 

 stalks near the base. The fungus was causing no injury to the celery. 

 When examined in the laboratory, the mycelium and sclerotia proved 

 to be those of Rhizoctonia. Pure cultures of the fungus were obtained 

 readily from the sclerotia. Repeated examinations of new shipments 

 of celery from New York showed that in the majority of cases Rhizoc- 

 tonia was present between the stalks. 



Duggar and Stewart 32 in 1901 were the first to report Rhizoctonia 

 causing a destructive damping-off of celery seedlings. Rolfs 95 in 1905 

 reported a damping-off of seedlings in Florida caused by Corticium 

 vagum B. & C. Van Hook 186 found a Rhizoctonia associated with a 

 root rot of celery in the field. He did not believe, however, that this 

 fungus was the cause of all the trouble. Affected plants never attained 

 full size, and an examination of the roots showed considerable decay. 

 The disease seemed to affect the main roots, which rotted off rapidly 

 near the crown. The fact that seed beds in new soil did not entirely 

 control the trouble showed that the fungus Rhizoctonia was present in 

 the new soil, tho not in any great amounts. Halligan, 51 in Michigan, 

 has also studied the damping-off of celery plants in the seed bed. 



Centaurea gymnocarpa 



In the spring of 1914 a large number of seedlings of Centaurea 

 gymnocarpa, including some of those which were potted, damped off. 

 By June many of the potted plants were dying with stem rot, the dis- 

 ease having been carried over on affected seedlings and in a few cases, 

 no doubt, on healthy ones. Microscopic examination and pure cultures 

 showed that in each case R. Solani was present in the diseased tissues. 

 The progress of the disease was rather typical. The first symptom 

 was the wilting and drying up of the foliage. On pulling up the 

 plant, a number of the leaves were seen to be rotted off at the crown, 

 while the bark on the stem below the surface of the ground sloughed 

 off and the tissues beneath were wet and stringy. 



CLOVER, RED, Trifolium pratense 



In the spring of 1914 damping-off of red and Japanese clover was 

 observed in the agronomy greenhouses. A culture easily obtained 

 from the fungus appeared to be the same in all respects as the one 

 isolated from alfalfa seedlings which were growing under similar con- 

 ditions in close proximity. 



Stevens and Wilson 122 in 1911 reported that in a field of clover in 

 North Carolina the roots were being attacked by Rhizoctonia and were 

 suffering some damage. This is the only instance in which Rhizoctonia 

 has been reported as injuring clover in the field. 



