COBB S DISEASE OF SUGAR-CANE. 



In 1894, a correspondent of The Sugar Cane described a serious disease of cane at 

 Pernambuco, Brazil (lat. 8 S.). His account makes it still more certain that the Brazilian 

 disease is none other than the one here under consideration. The Pernambuco disease is 

 described as follows: 



It may interest some of your readers to remind them of some features of the disease which for 

 many years threatened the existence of the sugar industry in the Province of Pernambuco, and in 

 other provinces of Brazil. 



Unfortunately, in one sense, before the observations which are the subject of this note were 

 made, the evil had so far diminished that it was difficult to obtain sufficient specimens to permit of 

 a thorough investigation, and other cir- 

 cumstances cut short the proposed in- 

 vestigation almost at the commencement. 



The unfortunate "Otaheite" cane, 

 or "Cayanna" cane, as it is called in 

 Brazil, was here as elsewhere the prin- 

 cipal victim, and nine-tenths of the cane 

 grown was of this kind. A green striped 

 cane called here Imperial, and a small 

 yellow cane, called Creoula, also suffered. 



The most striking symptoms were: 



Gum. The formation of a bright 

 yellow, gummy substance, exuding appar- 

 ently from the ends of the fibres on 

 cutting the cane across. Sometimes this 

 yellow gum, which turned orange colour 

 on drying, appeared only after half an 

 hour or more, at other times it appeared 

 immediately on cutting the cane, and in 

 such quantities as to drip from the cut 

 ends, and in very bad times is said to 

 have frequently choked the strainers of 

 the raw-juice tank. 



Premature death. Indicated by the 

 early drying up of the leaf tips; by the 

 successive joints becoming shorter and 

 less in diameter as the cane grew, giving 

 it the appearance of the joints having 

 been telescoped one into another; by 

 some internal parts turning red, denoting 

 fermentation, which may have set in be- 

 fore or after the cane had succumbed, 

 and by the death of the eyes. 



Any or all of these symptoms may 

 have occurred together, and some canes, 

 which to all outward appearance were 

 perfectly healthy and well developed, 



Fig. 3. 



contained a quantity of the yellow gum, together with a normal percentage of sugar. 



The canes which did not die before maturity gave no ratoons, and the juice was most difficult 

 to work, refusing to crystallize in the ordinary way, sometimes in any way. The greatest difficulty 

 was encountered in the "old process" factories, probably on account of the great heat accompanying 

 open evaporation. The Usines, with their lower temperatures, could work better, but they also at 

 times got the "devil in the house," especially if they did not take care to use but little lime in the 

 defecation. The lime was frequently reduced to 10 grammes per hectolitre, and in this way the juice 

 worked best. 



The appearance of this disease has not been assigned to any distinct causes. 



All the varieties attacked have been cultivated for many years in the most primitive manner. 

 The usual method still generally followed in Brazil is to dig shallow narrow holes very close to one 



*Fig. 3. Field of sugar-cane in New South Wales. The plants in the foreground grew from sets which were slightly 

 diseased by Bacterium vascularum when planted; those in background grew from healthy sets. After Cobb. 



