PARASITIC RHIZOCTONIAS IN AMERICA 333 



In 1904 Clinton 1 4 observed a damping-off and root rot of radish 

 due to Rhizoctonia. Apparently the disease was not very serious. 

 Stewart 125 in 1910 also reported a damping-off and root rot of radish 

 due to Rhizoctonia. Infection took place first at the level of the soil, 

 causing the leaves to have a wilted, drooping appearance. From this 

 point the disease spread into the leaves and roots of the plant, soon 

 causing death. On mature radishes, decayed spots of irregular shape 

 were produced, and at an advanced stage the diseased portions of the 

 plant were covered with a white, felted mycelium. 



RHUBARB, Rheum rtiaponticum 



In 1901 Duggar and Stewart 32 reported a disease of rhubarb, on 

 Long Island, which they had had under observation for several years. 

 They described the disease as follows : 



"An unthrifty condition of the plants was noticed, followed by the rapid 

 dying off of many of the leaves. The affected leaves became dry and shrunken 

 in appearance and soon fell to the ground. Where a field was badly affected, 

 the majority of hills showed the trouble to the extent of at least a leaf or two. 

 In several instances from one-fourth to three-fourths of the leaves were already 

 dead. An affected leaf breaks off readily just beneath the surface of the ground, 

 and old dead leaves rotted off in this region. The general appearance reminded 

 one strongly of the effect of Ehizoctonia upon beets. There was very little super- 

 ficial mycelium visible to the unaided eye. Microscopic examination showed 

 hyphse of a Khizoctonia both superficially and immediately under the surface where 

 the leaves were rotting? 7 



Clinton 14 has also reported a stem rot of rhubarb due to Rhizoc- 

 tonia. He found the fungus at the base of leaf petioles, causing dark, 

 sunken cankers. 



SALVIA, Salvia splendens 



The symptoms of the Rhizoctonia disease of salvia observed in the 

 flori cultural greenhouses were similar to those described for coleus. 

 All varieties of the cuttings in the bench seemed to be equally suscep- 

 tible. It has been shown that the serious damping-off of the salvia, al- 

 ternanthera, and coleus was due to the fungus which was first brought 

 in on the mature alternanthera plants from which cuttings were made. 

 (See Alternanthera, page 310.) 



Santolina cliamcecyparissus 



In 1914 a number of plants of Santolina cliamcecyparissm growing 

 in pots next to the Centaurea gymnocarpa in the floricultural green- 

 houses, were found to have a typical stem rot, due to R. Solani, very 

 similar to the disease as described for that plant (see page 321). The 

 fungus could be distinctly seen running thru the bushy branches. 



