ARTIFICIAL AND INSECT TRANSMISSION OF SUGAR- 

 CANE MOSAIC 



By E. W. Brandes 



Pathologist, Office of Sugar-Plant Investigations, Bureau of Plant Industry, United 

 States Department of Agriculture 



The infectious nature of sugar-cane mosaic can hardly be questioned 

 in the light of field observations bearing out this point made in Georgia 

 and Florida last year and in Porto Rico during the preceding two 

 years (/) ^ Records of well-controlled inoculation experiments, how- 

 ever, have been wholly lacking. A number of investigators, beginning 

 with the Dutch workers in Java, have attempted to produce the disease 

 by artificial inoculation and by the use of suspected insect carriers; but 

 in all cases results have been negative or inconclusive. Where success 

 has been reported the experiments were carried on under unsatisfactory 

 conditions, and the results were repudiated by contemporaneous workers 

 who attempted to repeat the experiments. Kamerling (j) in 1902 

 reports that he secured infection by inoculating healthy plants with sap 

 from diseased plants. He says (in translation) : 



So far as the kind of disease is concerned, we are dealing with a disease analogous 

 to the notorious mosaic of tobacco, that is, with an infectious disease, which, how- 

 ever, in all probability is not caused by a parasitic organism. 



As is the case with tobacco mosaic, the disease has been successfully transmitted 

 by inoculating healthy plants with juice pressed out of diseased plants. (Footnote: 

 My inoculations with juice of diseased cane were performed in the same way as the 

 inoculation tests of Beijerinck with juice of tobacco plants affected with mosaic.) 



These inoculation tests, however, throw little light on the manner of origin and of 

 dissemination in nature. 



One very great difficulty in carrying out tests on the way in which the disease oviy 

 tnates and is disseminated in nature is in securing cuttings that do not have a predis- 

 position toward the disease. From the best possible selected Moga cuttings a certain 

 number of check plants in my pot cultures showed stripe disease ; and I have had a 

 similar experience with specially selected cuttings from Van Delden in Soekaboemi, 

 which in Koeningen produced a crop practically free from disease. 



This vague reference to his experiments and his admission of disease 

 in the control plants was not very convincing and was discredited by later 

 Dutch investigators. Kobus (4), van der Stok (6), and Wilbrink and 

 Ledeboer (7) were unable to produce the disease by using the method of 

 Kamerling. Wilbrink and Ledeboer say (in translation) : 



So sudden a severe outbreak as Kobus already observed gives rise to the suspicion 

 that we are perhaps dealing with an infectious disease, as is the case, for example, with 

 the mosaic disease of tobacco, analogous to the stripe disease in very many respects. 

 Dr. Kamerling states in the Annual Report of the Experiment Station of Kagok for 



' Reference is made by number (italic) to " Literature cited," p. 138. 



Journal of Agricultural Research, . Vol. XIX, No. 3 



Washington, D. C. May i, 1920 



uf Key No. G-190 



(i3i) 

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