286 THE BANANA 



elation of the value of the land. With regard to the first, 

 if a bunch of fruit is produced, it is apt to be small, and 

 is always rejected by the inspectors. With regard to the 

 second, immature plants die in enormous numbers before 

 any fruit is produced, and only rarely is a marketable 

 bunch obtained from an infected field. The third 

 type of loss namely, the depreciation in value of the 

 land is due to the fact that the causal organism of 

 the disease may remain for long periods in the soil, and 

 finally increase to such an extent that bananas can n 

 longer be grown. 



SYMPTOMS OF THE DISEASE : EXTERNAL 



In a field where only occasional and isolated cases of 

 the disease are found, indicating that the soil has not yet 

 become thoroughly infected, the affected plants are not 

 apt to exhibit any external signs of the disease until after 

 the bunch has started to form. A typically diseased 

 plant first shows a yellowing of the lower or outer leaf- 

 blades and petioles. The transition from the normal 

 dark green colour of the leaf to a vivid yellow is usually 

 sudden and startling, and proceeds from the margin 

 inwards. Its appearance to one familiar with the 

 disease is unmistakable, and not apt to be confused with 

 any other trouble. This yellowing of the outer or lowei 

 leaves is a practically certain symptom, especially if, as is 

 usually the case, it appears when drought symptoms are 

 not to be expected. There is no risk of confusing it with 

 the normal fall of the lower leaves. In a healthy plant 

 the older leaves gradually and regularly die off from below 

 upward, with only a gradual transition in colour from dark 

 green to brown. 



The leaves first attacked by the disease begin to wilt 

 almost immediately. Within a day or two the fleshy 

 leaf -stalk buckles, usually at a point 3 or 4 inches 

 from the stem, and the leaf hangs from this point. Some- 

 times this buckling of the leaf-stalk or the large midrib 



