76 BULLETIX 186. 



the tuber. A tuber may bear liundreds of sclerotia and yet be abso- 

 lutely sound. In this respect our Rhizoctonia appears to differ 

 from the European potato Rhizoctonia. Some writers report that 

 tlie latter is a common cause of potato rot. In other respects the 

 two forms are strikingly similar. AYe are under obligations to 

 Prof. Dr. Paul Sorauer, of Berlin, for excellent fresh specimens of 

 the European Rhizoctonia solani, from which cultures for inocula- 

 tion work have been obtained. 



On the Padish, Raphaniis sativus. 



In the winter of 1898 diseased radish plants of marketable size 

 were received from Saratoga, N. Y. The disease consisted of a 

 soft rot of the crown, or of large ulcerations in this region. As a 

 rule, the leaves w^ere unaffected until a considerable portion of the 

 root had decayed. It was reported, however, that plants in all 

 stages of growth were affected and killed. It proved to be a 

 trouble of considerable importance with forced radishes, and nearly 

 half of the crop was lost from this disease. It spread rapidly from 

 plant to plant in the row, and from well-established centers of infec- 

 tion. When the material was received, the tissues surrounding dis- 

 eased areas were infested with hyphse of a Rhizoctonia. These 

 hyplige were also very abundant superficially, growth being induced, 

 perhaps, by the moist conditions under which the plants had been 

 kept. A culture of the fungus was secured, and with half grown 

 radishes kept under moist conditions the disease was induced ; but 

 only a few plants were involved in this experiment. Unfortunately, 

 this culture was afterwards lost, and it has not since been observed 

 as a disease of mature plants. Nevertheless, Rhizoctonia has been 

 found occasionally in the greenhouse as a radish dam^jing-off fungus 

 of slight importance. 



On the Phubarb, Rheum rhaponticum. 



For several years a peculiar disease of rhubarb lias been observed 

 on Long Island ; but until the past season no satisfactory cause of 

 the trouble was evident. During July several rhubarb fields were 

 visited in the vicinity of Jamaica, and in many of these the leaves 

 were dying rapidly, the plants being in an unthrifty condition. 



