DISEASES OF SUGAR CANE 329 



from saliniferous deposits at deeper levels. The condition is thus 

 not dependent on an excess of lime, as is sometimes supposed, 

 but on the presence of salt in the soil water, a conclusion which 

 agrees with the observation that cane will grow quite normally 

 on soils with a higher lime content than those affected. 



No permanent remedy has been found. Experiments in Porto 

 Rico have shown that temporary recovery of colour follows the 

 application of iron salts. 



In order to complete the review of diseases attacking the 

 sugar cane, a brief account is added of two diseases which have 

 been recognised in the Pacific Region for a number of years, but, 

 as in the case of Sereh, are not known to occur in the West Indies ; 

 these are the so-called Fiji Disease and the Sclerospora disease. 



Fiji Disease. 



This disease owes its name to the fact that it was discovered 

 in the Fiji Islands (about 1905), where it threatened the stability 

 of the industry ; it was found later in Australia and New Guinea, 

 and more recently in the Philippines. 



The unique and characteristic symptom of the disease is the 

 occurrence of elongated swellings or galls on the under sides of the 

 leaves ranging in length from i /12th to several inches and re- 

 stricted to the large veins. According to H. L. Lyon, similar 

 galls may be found in the vascular bundles of the stems. A 

 stalk may grow to a considerable length and develop a succession 

 of galled leaves, otherwise normal in appearance ; finally and 

 rather suddenly, only short crumpled leaves, often reduced to 

 stumps, unfold from the spindle, growth ceases, and the death 

 of the stalk follows. After the disease has appeared on a single 

 stalk the whole stool becomes involved and finally succumbs. 

 The disease is invariably transmitted in cuttings from affected 

 canes, and the soil may carry the infection for a time with the 

 result that susceptible varieties may make practically no growth 

 when planted in such soil. No immune variety of cane has been 

 found but the New Guinea cane Badila is strongly resistant 

 and is now the most widely planted kind in Fiji. The disease 

 has been brought under practically complete control in Fiji by 

 rigid selection of cuttings only from healthy stools ; experience 

 has shown that this selection must be maintained even after 

 disease has been reduced almost to the vanishing point. Plas- 

 modium-like bodies occur regularly in the cells of the gall- 

 tissue and this observation has led to the belief that Fiji disease 

 might be due to a slime-mould (myxomycete) related to Plas- 

 modiophora brassicce Wor., the well-known cause of club-root 

 in plants of the order Cruciferae. 



