May 13, 1910] 



SCIENCE 



755 



vails, especially in bananas used as shade for 

 tobacco, but I have received several lots of dis- 

 eased material, and now have affected plants 

 growing in one of the Washington hothouses. 



The signs of the disease so far as I have been 

 able to obtain them from Cubans, and as the 

 result of my own examinations, correspond quite 

 closely to those described by Dr. McKenney, and 

 also to the banana disease described by Mr. Earle 

 from Jamaica in 1903. A similar, if not identical, 

 disease prevails in Trinidad, according to state- 

 ments made to me by Mr. James Birch Rorer, 

 from whom I have also received alcoholic material. 

 A similar disease occurs in Dutch Guiana, accord- 

 ing to statements recently received by me from 

 Dr. van Hall, director of the experiment station 

 in Suriname. I am inclined to think that the 

 Central American disease is also the same as this 

 disease, although we are not yet certain. Dr. 

 McKenney and myself having joined forces to 

 settle, if possible, the problems relating to banana 

 diseases in these regions. Possibly there are two 

 banana diseases now confused — one due to bac- 

 teria, the other to fungi. 



A microscopic examination of the Cuban ma- 

 terial showed bacteria to be present in some of 

 the vessels, but not in quantity sufficient to lead 

 me to suppose them to be the cause of the disease. 

 In passing, I might say that Earle sent me cul- 

 tures of the bacteria isolated by him from the 

 diseased Jamaican bananas and that in the sum- 

 mer of 1904 I inoculated these copiously into the 

 leaf-blades and petioles of bananas in Washington, 

 but without production of any disease. In the 

 Cuban plants no fungi were observed at first, but 

 further studies revealed a small amount of 

 mycelium running in the vessel walls or their 

 vicinity, but in no case plugging the lumen of 

 the vessels. No spores were observed at first, 

 but after awhile I thought I made out, although 

 rather indistinctly, one or two microconidia, and 

 jumped to the conclusion that the fungus was a 

 Fusarium. Poured-plates were then made from 

 the interior of affected leaf-stalks which were 

 sound on the surface and a Fusarium was ob- 

 tained on the plates in practically pure culture, 

 the colonies having evidently been derived from 

 microconidia present in the bundles. Transfers 

 were made from these colonies and after a half- 

 year or more, rapidly growing, large banana trees 

 were inoculated from subcultures. The inocula- 

 tions were made by means of punctures into the 

 midrib, leaf-stalk and pseudo-trunk. At this time 

 the bananas were about twenty feet high, perfectly 



healthy and with trunks a foot in diameter. As a 

 result of these inoculations the writer obtained 

 infection of the vascular bimdles of the petiole of 

 several leaves to a distance of from five to eight 

 feet and more from the point of inoculation. 

 The bundles became brown-purple in the typical 

 manner and the Fusarium with microconidia was 

 demonstrated in the interior of these biondles by 

 microscopic examination, especially after treat- 

 ment with 10 per cent, potash (drawing exhib- 

 ited), and was also isolated from the same at 

 this distance from the point of inoculation by 

 means of Petri-dish poured-plates, the exterior of 

 these petioles being at the time perfectly sound. 

 It has thus been demonstrated beyond dispute 

 that the affected Cuban plants contain a Fusarium 

 which is able to run long distances inside of the 

 vascular bundles and cause a purple, purple-brown 

 or blackish stain of the same. What has not yet 

 been demonstrated is that such inoculations will 

 so disease the rootstock that other uninoculated 

 leaves will subsequently show the typical signs 

 of the disease. I was obliged to break off this 

 experiment after about two months, owing to the 

 necessity of moving the hothouse, and building 

 another one before experiments could be con- 

 tinued. The rootstocks from which the inoculated 

 infected leaves were cut away have, however, been 

 planted out in the new house, and additional 

 inoculations have been made, the results of which 

 ought to be positive one way or the other in the 

 course of the coming year. 



The fungus may be designated for the present 

 as Fusarium Cubetise. It produces macroconidia 

 and microconidia of typical form, reddens and 

 purples various culture media, and has not so 

 far shown any ascospore form. The chief char- 

 acteristic separating it from other species so far 

 as yet known is its location in the diseased 

 banana plant and its ability to produce the before- 

 mentioned disorganization phenomena in the vas- 

 cular bundles, but no doubt other peculiarities 

 will be developed as the study of the organism 

 progresses. 



A very considerable part of the banana holdings 

 in tropical America are in the hands of Amer- 

 icans, and as we also consume the greater part 

 of the product, it is highly important to prevent 

 such destruction of the plantations as shall lead 

 to a loss of American capital and an increase in 

 the price of this important food product. 



The Blackleg Disease of the Potato in America: 

 Professor W. J. Moese, Maine Agricultural 

 Experiment Station. (Read by title.) 



