THE PESTS AND DISEASES OF THE CANE 



169 



As with the other causes the connection of this fungus is not accepted, 

 and the general opinion seems to be that sereh is the manifestation of peculiar 

 soil and cultural conditions, the organisms which have been observed only 

 becoming prominent after the health of the cane has been affected. However, 

 the very latest Java studies indicate that a connection may exist between 

 sereh, gumming and yellow stripe. 



The infectious nature of the condition is uncertain. The disease spreads 

 from district to district in Java, and on the other hand healthy stalks planted 

 in an infected field remained healthy. Whether infectious or not the disease 

 was found to be passed on from plant to plant, that is to say sound seed 

 gave sound canes, while seed from sereh-infected canes gave sereh-infected 

 stalks. 



The localization of the disease or not in Java is of great 

 interest. It has been recognised definitely in Malacca, Bangkok 

 and Borneo, and references to canes with the appearance of sereh 

 in India, Australia, Mauritius, Porto Rico, Hawaii and Trinidad 

 are to be found in the literature. Went observed canes in 

 Surinam with all the symptoms of sereh, and noticed at the same 

 time the presence of the Hypocrea, but in no instance outside of 

 Java have the manifestations reached the epidemic stage, re- 

 maining rather as isolated instances in individual canes. 



Yellow Stripe, Mottling Disease, or Mosaic Disease. This is 

 a condition which was first studied in Java. Lately (1916) the 

 condition has reached the epidemic stage in Porto Rico, 110 and it 

 is not unknown in Hawaii, Louisiana and Argentina. Canes 

 presenting all the symptoms of yellow stripe may also be found 

 in Cuba. The manifestations present themselves most con- 

 spicuously in the leaf, which, when viewed by transmitted light, 

 presents a peculiar mosaic 01 mottled appearance due to spots 

 of yellow colour. In cases of severe attack the spots coalesce to 

 give the appearance of a yellow stripe. At the same time the 

 joints of the cane exhibit a shrinkage, with the eventual ap- 

 pearance of gray cankers. Accompanying the manifestation is 

 a diminution of the weight of the crop, but there is no decrease FIG. 70 

 in the sugar in the affected portions. These results naturally 

 follow on the immobilization of a portion of .the leaf surface. The disease 

 is progressive in that ratoon cane is more infected than is plant cane, and 

 it is also hereditary, cuttings from infected cane transmitting the condition, 

 and in this observation lies one of the means of control. Although no or- 

 ganism has yet been associated with the condition, it has been established 

 that the disease is infectious. The latest view is that Mosaic is transmitted 

 by sucking insects. 



Chlorosis. Under certain conditions canes develop yellow stripes in 

 the leaves due to absence of chlorophyll, and as a condition quite distinct 

 from that described above. This condition occurs in soils containing a large 

 quantity of calcium carbonate, and has been observed in Antigua, Barbados, 

 Jamaica, Cuba and Porto Rico, where it has been studied as a serious con- 

 dition by Giles and Ageton. 111 The condition is due to disturbance of the 

 physiological functions of the plant, and may be temporarily remedied by 

 applications of sulphate of iron to the leaf or to the soil. Areas in which it 

 occurs are known in Antigua as gall patches or moonstruck canes, and 



