314 BULLETIN No. 189 \June, 



In 1904 Hedgcock 00 reported as follows : 



"The bean crop in the vicinity of St. Louis was severely injured by a Khi- 

 zoctonia which attacked the stems and large roots of the plant and also produced 

 brown sunken areas on the surface of the pods, penetrating the latter and discolor- 

 ing the seeds. An examination of a number of seeds whose surface was discolored, 

 disclosed the fact that the mycelium of the fungus had established itself in the 

 second coat and in many instances had formed minute sclerotia there without rot- 

 ting the seed or even penetrating the cotyledons. The presence of the fungus did 

 not prevent the germination of the seed." 



Fulton 44 in 1908 showed that Rhizoctonia from infected pods 

 caused damping-off of seedling beans and of month-old plants. 



A serious outbreak of the stem rot of beans was reported from New 

 York by Barrus 9 in 1910. He found that in some fields as many as 

 30 percent of the plants were infected. In the same fields during the 

 following season it caused the death of at least 5 to 6 percent of the 

 seedlings; later in the season, after a rainy spell, a large percentage 

 of the pods in contact with the ground became infected. 



BEET, Beta vulgaris 



Young seedlings of the garden beet, in flats, were found damping 

 off in the vegetable-gardening greenhouses of the Station, July 10, 

 1913. Cultures showed that K. Solani was the sole cause of the dis- 

 ease. Characteristic lesions were found on the beets at the surface of 

 the ground, and strands of mycelium could be plainly seen spreading 

 out on the surface of the soil. 



As with root rot of other fleshy crops, the fungus gains its first 

 held at the crown of the mature plant, which, as a rule, is just below 

 the surface of the ground. The first evidence of the disease is a 

 darkening of the leaf bases, followed by the rotting of the crown. 

 The leaves retain their color for a long time, or until the leaf stalks 

 rot off almost completely. With the rotting at the crown, the beets 

 begin to crack from this point. While the tissues around the cracks 

 remain firm, as a rule, for a long time, the crown is usually soft, a 

 condition due to the entrance of other organisms. Lesions are some- 

 times formed on the sides of the beets, often extending deep into the 

 tissues. When weather conditions become unfavorable to the fungus, 

 the rotting and cracking stops and the plant may recover from the 

 attack. The disease is generally scattered thru the field, only a few 

 plants in a given area being affected. 



Under the name Rhizoctonia betce Kiihn, Pammel 76 in 1891 de- 

 scribed a root rot of sugar beets. He was the first investigator to re- 

 port serious damage caused by Rhizoctonia in this country. Duggar 28 

 in 1899 regarded the root-rot disease of sugar beet due to Rhizoctonia 

 as one of the important diseases of that plant. At the present time 

 this disease is very widespread and is the cause of considerable loss, 

 especially in irrigated regions. 



