DISEASES OF PLANTS. 55 



Report of the vegetable pathologist, H. Tryon {Queensland Dept. Afjr. Rpt. 

 1S99-1900, pj). 30, SI) . — Brief notes are given on the occuiTence of a number of dis- 

 eases ujion various economic plants. 



The sterile fungus Rhizoctonia as a cause of plant diseases in America, 

 B. ^I. DuGGAR and F. C. Stewart {New York Cornell Sla. Bui. 18G, jyp- 31-76, Jiijs. 9; 

 Xeir York Sfafe Sta. Bid. 1S6, pp. 30, figs. 9). — This investigation was conducted by 

 cooi)eration ])etween the two New York stations. A brief account is given of the 

 morphology of the fungus, and some of the more destructive of the American forms 

 are described. Sterile Rhizoctonia produces diseases of the bean, beet, carrot, celery, 

 cotton, lettuce, potato, radish, rhubarb, ornamental asparagus, china aster, carna- 

 tion, sweet William, and violet, as well as being apparently the cause of diseases 

 upon a number of other plants. In many cases Rhizoctonia is truly parasitic, and 

 the diseases of l>eet, carnation, lettuce, and others have been repeatedly caused by 

 the authors by placing pure cultures of the fungus in contact with the plants. In 

 other cases the fungus is found associated with the disease, but as yet there is no 

 proof that it is the chief cause of the trouble. The fungus is believed to be capable 

 of prolonged existence upon decaying organic matter in the soil, and in this way 

 it may be spread from plant to plant, even when culture or other means fail to 

 spread it. Plants growing under favorable conditions of moisture, temperature, and 

 nutrition will probably show marked resistance to the attack of the fungus, so that 

 in seeking to prevent this disease good sanitary conditions are of the greatest impor- 

 tance. In the propagating and forcing benches, where the fungus is commonly pres- 

 ent, a frequent change of soil is advisable. Should the fungus prove a serious pest in 

 greenhouses, the sterilization of the soil with steam or hot water is recommended. 

 The fungus grows readily upon acid media, and as a consequence liming of soil, while 

 not thorouglily effective, will frequently prove beneficial. 



Plant diseases due to Rhizoctonia, F. H. Hall, B. M. Duggar, and F. C. 

 Stewart {New York State iSta. Bui. 186, popular cd., pp. 11, pis. 2, figs. 2). — This is a 

 popular summary of the bulletin noted above. 



A second preliminary report on plant diseases in the United States due to 

 Rhizoctonia, B. ■\I. Dtggar and F. C. Stewart {Abs. in Srienrr, n. .scr., 13 {1901), 

 No. 320, p. 249). — Since the publication of the previous notes on diseases caused by 

 Rhizoctonia (E. S. R., 11, p. 57), the authors have observed the fungus on a number 

 of entirely new host plants. The princii^al host plants of this fungus are beans, 

 sugar beet, cabl)age, cauliflower, carrot, celery, cotton, lettuce, potato, radish, rhu- 

 barb, asparagus, china aster, carnation, coreopsis, sweet william, and violet, with 

 about a dozen other plants of less importance. In many cases the Rhizoctonia 

 proves to be truly parasitic and undoubtedly the cause of the disease, as is shown by 

 abundant experiments, while in other cases innoculation experiments have not been 

 performed. Studies are in progress to determine more carefully the physiology of 

 the forms and the limitations of the species. 



The wilt disease of cotton and its control, W. A. Orton {U. S. Dept. Agr., 

 Division of Vegetable Physiology and PatJiology Bid. 27, pp. 16, pis. 4)- — The wilt dis- 

 ease of cotton is widely distributed through the South, having been reported from a 

 number of places in South Carolina, Georgia, Florida, and Arkansas. The extent of 

 loss from this source is very considerable, in some places cotton culture having been 

 abandoned on infected soil. A description of the disease, together with its cause, is 

 given. The nature of the fungus {Neocosmospora vasinfecta) has been previously 

 described by the Division (E. S. R., 11, p. 944). In addition to cotton, this same 

 disease is believed to occur on okra, and in both the okra and cotton it is sometimes 

 complicated by the presence of root nematodes {Heterodera radicicola). The progress 

 of the disease is relatively slow when compared with others, on account of its being 

 a soil fungus. Natural and artificial infections from cultures of it are described, and 

 experiments with fungicides for its prevention are outlined. Some of the common 



