EXPEEIMENT STATION RECORD. 243 



DISEASES OF PLANTS. 



Crown gall of plants, its cause and remedy, E. F. Smith, Nellie A. Brown, 

 and C. O. Townsend ([/. 8. Dept. Afjr., Bur. Plant Indus. Bui. 213, pp. 215, 

 pis. 36, figs. 3). — This bulletin includes a brief history of investigations on the 

 crown gall of plants in the United States and other countries, and detailed 

 studies of the disease covering a period of six years. 



The results are given of confirmatory inoculation and cross-inoculation 

 experiments with the crown gall organism from the daisy {Chrysanthemum 

 frutescens), arbutus, grape, alfalfa, peach, rose, quince, beet, hop. chestnut, 

 poplar, and apple. The relationship of crown gall to hairy root is discussed, 

 and experiments with the hairy root organism reported. The morphological 

 and cultural characters of the causal organism as isolated from the crown gall 

 of the daisy are described in full; the characters and observed differences in 

 crown gall organisms from various sources are also noted. The authors dis- 

 cuss the question of species, varieties, and races of crown gall organisms, 

 structure and growth of the tumors, chemical and physical changes produced 

 in the gall and on adjacent but not directly involved tissue, physiological 

 effects, losses due to the disease, and the best methods of dealing with it. 



It is stated that crown gall is a disease common in nurseries on the roots and 

 shoots of various plants and which may persist on the plants after their 

 removal to orchards, vineyards, gardens, and hothouses; it also occurs on 

 various field crops. The causative organism, at least that for the daisy galls, 

 is a white schizomycete. Bacterium tumefaciens (E. S. R., IS, p. 950). This 

 organism does not produce open cavities in the host, but seems to be present 

 in small numbers in the living cells, causing a rapid proliferation, especially 

 in soft and rapidly growing tissues. Cross inoculations wnth the daisy organ- 

 ism have produced tumors on many species in widely separate parts of the 

 natural system (Compositae to Salicacese). Schizomycetes grown from natural 

 galls of the peach, apple, rose, quince, honeysuckle, arbutus, cotton, poplar, 

 chestnut, alfalfa, grape, hop, beet, salsify, turnip, lettuce, and willow have 

 been isolated, which closely resemble (as gi-own on agar) B. tumefaciens of the 

 daisy, and some eight of which are able to produce tumors on the daisy and 

 other plants, indicating that crown gall on all of these hosts is due to a poly- 

 morphic species, rather than to several distinct species. 



Hard and soft galls and hairy root seem to be due to the same organism. It 

 is claimed that crown gall is a disease which progresses slowly, stunting the 

 plant at first, and finally destroying it unless removed by pruning or by the 

 development of increased resistance of the host. Rigid state inspections and 

 the rejection of diseased nursery stock are recommended. 



These abnormal growths of plants designated as tumors or galls are believed 

 by the senior author to be like malignant animal tumors in various particulars, 

 such as permanent and very rapid new growth of affected tissues, enormous 

 round-celled or spindle-celled hyperplasia, great reduction of the amount of 

 conductive tissues, early necrosis Muth renewed growth at the margins, frequent 

 recurrence after extirpation, extension of the disease to other parts by 

 metastases, etc. 



In the course of investigations on crown gall, a new disease of the sugar beet 

 was discovered, due to a yellow schizomycete for which the name Bacterium 

 beticolum n. sp. is proposed. The disease is called tuberculosis of the beet, 

 and is characterized by overgrowths of a coarse nodular nature which soon 

 disintegrate, leaving small cavities in the tissues. 



Some troubles of New York plants, F, H. Hall (New York State Sta. Bui. 

 328, popular eel., pp. 12, figs. 2). — This is a popular edition of Bulletin 328 



