DISEASES OF BANANA 247 



points oval patches, up to several inches in diameter, of a dark 

 brown colour, and watersoaked in appearance. The spots 

 usually penetrate two or more leaf-sheaths, becoming smaller 

 as they progress inwards. In extreme cases they reach the 

 centre of the trunk. When the discoloration passes from one 

 leaf-sheath to the next, superficial white mycelium may be 

 developed between them. 



The surfaces of the leaf-scales below the soil as well as the 

 bases of the leaf-sheaths are frequently covered with white 

 mycelium, and the leaf-scales are discoloured brown. 



Many of the roots are shrivelled and dead for part of their 

 length. The cortex becomes brown and soft and eventually the 

 vascular cylinder darkens and decays. Infested plants are 

 easily uprooted. 



On cutting across the trunk the inner leaves are healthy 

 except where the brown patches have penetrated. The vascular 

 bundles are not discoloured in either trunk or rootstock. 



The disease spreads from the outside and appears to begin 

 on the outer leaf-sheaths, usually near soil level. In this situation 

 the Marasmius fructifications are freely produced during wet 

 weather. The caps are pale yellowish white to pale reddish tan, 

 the stalks white at the apex, pale reddish below, the spores 

 ellipsoid, smooth, 7-9 x 5-6 microns. 



Conditions of Occurrence. 



As to the nature of this disease a good deal of the discussion 

 regarding root disease of sugar-cane will apply. It occurs as 

 the effect of drought, poverty of soil, or defective soil aeration 

 due to lack of drainage or of tilth. It is of small account on good 

 soil adequately watered, but may be severe on gravelly or sandy 

 soil and poor land generally. Drainage, manuring, cultivation, 

 and the use of healthy suckers for planting are the measures of 

 control indicated. 



The Moko Disease. 



A disease of banana and plantains in Trinidad was investigated 

 in 1909-10, by J. B. Rorer, and found to be due to a bacterium, 

 not yet described, for which the name Bacilhis Musce was 

 suggested. The disease was first found on the " moko," a coarse 

 banana at one time largely used for shading young cacao in 

 Trinidad, but reported to have been almost exterminated by an 

 epidemic somewhere about 1890. The disease attacks other 

 varieties of banana, including the dwarf Chinese or Canary type 

 resistant to Panama disease. The Gros Michel, which is very 

 susceptible to Panama disease, is highly resistant to the moko 

 disease. 



