CHAPTER XIII 

 FUNGUS DISEASES 



1. DISEASES OF THE BULB AND LEAVES 



Panama and Costa Rica. McKenny, in May 1910,* gave 

 an account of a disease in Panama and Costa Rica. The 

 disease was first noticed among the various plantations in 

 Panama, in 1906, in fields five to six years old. From 

 certain spots it spread all round, affecting at last a con- 

 siderable area. The fields when ten years old were 

 absolutely worthless. Thirty miles from this district the 

 disease makes its appearance, but only sporadically. In 

 Costa Rica it is serious in certain localities. 



" Commonly the first external sign is a rapid yellowing 

 and subsequent browning and wilting of one or more leaves. 

 Sometimes there is a striking curvature and yellowing of 

 the terminal part of the leaf blade while the remainder is 

 still green. Eventually all the leaves die and fall back 

 against the trunk, leaving a crop of suckers which in turn 

 are killed and give place to still weaker shoots. The fruit 

 of diseased shoots rarely matures, and even when mature is 

 worthless, with blotched, somewhat shrivelled surface and 

 dry, pithy interior. Shoots which develop after one or 

 two suckers have died rarely reach the flowering stage ; 

 when they do, however, weak, distorted, worthless bunches 

 are produced. On cutting the pseudo-stem [trunk] across 

 and longitudinally many of the bundles are found to be of 

 a yellow, reddish or reddish-purple colour, the colour 

 deepening towards the root-stock. In the last stages the 

 colour of the bundles may be almost black. While in 



* Science, xxxi. 750. 

 83 



