238 INSECTS, DISEASES AND OTHER PESTS 



two diseases it was suggested by us some time ago that 

 the first be called " branch rot," for it rarely if at all attacks 

 the stem of the Carnation plant, while the latter could be 

 properly called " stem rot." 



The stem rot which has caused the Carnation growers 

 so much trouble, and which has so often been called the 

 most serious disease of Carnations, is caused by a fungus 

 called Rhizoctonia. This disease was first reported on 

 Carnation and other plants about 1895. About 1900, 

 several investigators published a number of papers on the 

 rhizoctonial diseases of Potatoes, Beets and on a large 

 number of other vegetables and field crops. Mention was 

 also made of this disease on Carnation, Sweet William, 

 China Aster and other floricultural crops, both in the 

 field and greenhouse. Since this time little work has 

 been done on the " stem rots " of floricultural plants caused 

 by Rhizoctonia, although this disease has been causing 

 considerable damage to a number of plants, especially the 

 Carnation. 



The symptoms of this disease are probably well known 

 to most Carnation growers; the fungus usually attacks 

 the plant at its crown, that is, where the stem enters the 

 ground. It may enter at the surface of the ground, occa- 

 sionally above, or below. From records kept the last two 

 years it has been found that a plant with a single stem 

 breaking about 2 in. from the ground is much more re- 

 sistant to the fungus than a plant forking at or below the 

 surface. It has also been observed that the former is 

 generally attacked about an inch below the ground, while 

 the latter forking just at or below the ground's surface, 

 is not attacked by the fungus at the main stem. Usually 

 one branch rots off first followed by the others in turn. 

 At times several branches below ground like this may be 



