84 THE BANANA 



recently affected plants the vessels of the upper part of the 

 stalk and the leaves may be normal, those of the root- 

 stock [bulb] are always coloured. ... A nauseating odour 

 is often given off when leaf stalks which have been diseased 

 for some time are cut open, though there may be no sign of 

 rotting in the trunk." 



McKenny found both bacteria and fungus hyphae in the 

 gummy substance blocking cells and vessels of the xylem- 

 portion of the vascular bundles, but did not determine the 

 cause of the disease. 



H. Levy described the disease in Costa Rica in 1910.* 

 He points out what seems to be a characteristic of this 

 particular disease, that the sheaths of the trunk of young 

 plants split from the bulb upwards for a distance of one to 

 two feet, sometimes right through to the heart, in which 

 case the young embryo leaves push out through the 

 aperture and develop. " With the older plants the first 

 sign of infection is manifested in a different way : a fringe 

 of yellow will appear on the lower leaves of the plant. . . . 

 After a few days the entire lot of leaves turn yellow ; at 

 this stage it is often confounded with suckers suffering 

 from drought or lack of drainage, but in a few days the 

 disease puts on another symptom which is peculiar to it. 

 All the leaves suddenly turn a brown colour and hang 

 quite limply down the side of the sucker, the heart, leaf, 

 and bunch, if young, turning black. ... In a ' sick ' 

 bunch the tips of the fingers present a pinched-in appear- 

 ance, something like dry-weather fruit, when it starts to 

 ripen in the open. It will not do so evenly as a healthy 

 bunch would, but one finger here and there all over the 

 bunch, the yellow fingers showing up in contrast to the 

 green ones. . . . 



" The leaves have not such a crisp feel as those that 

 are found on dry-weather bananas or from the natural 

 shedding of the leaves, but a soft damp feel, which con- 

 tinues until all the moisture dries out ; it is only a matter 

 of time when the whole tree rots to the ground, giving off 

 * Journ. Jam. Agric. Soc., xiv. 241. 



