260 



" It is now clear that the existence of the disease in the roots^ 

 thoufch fairly general, is only secondary. Examples have been seen 

 in which the roots were affected only in the slightest degree. The- 

 centre of infestation is the Ted zone in the stem, which is simply 

 a vast breeding ground of the worm. From this it extends more 

 or less along the roots, and, what is much more serious in imme- 

 diate results, to the leaves. This includes not only the mature and 

 semi-mature leaves which progressively fail 'in the familiar manner, 

 but the very youngest rudimentary leaves, only a few inches long, 

 in the centre of the bud. It appears to be this infestation of the 

 leaves which brings about the death of the tree. In plantations 

 where the trees are uniform in age, the disease typically appears 

 first in widely and thinly scattered cases when the trees approach 

 bearing age. This can occur equally on virgin forest soil or on 

 old cultivated land. The worms may come from some unknown 

 alternative host, not coconut, but the balance of probability seems 

 at present to be with the conclusion that they are introduced with, 

 the seed nuts. 



" From the centres of infection thus established, the disease ex- 

 tends to surrounding trees, and the resulting losses can be very 

 serious. I have already seen or heard of several instances in which 

 they approached 30 per cent. 



" The process of natural infection, and the length of time re- 

 quired for development remain to be investigated. Three trees in 

 Grenada inoculated in the stem 1 to 2 feet from the ground were 

 fully infested and failing in sixty days. A tree inoculated in the 

 stalk of a leaf had a rather general but 'not fully developed infesta- 

 tion in seventy-four days. A tree in which material was (placed 

 among the leaf bases without inoculation was fully infested in stem 

 and leaves in seventy-four days, while a tree similarly treated in 

 one leaf base had seventeen infested leaves at the end of the same 

 period. 



'■ It thus appears that infestation may take place among' the 

 leaves without previous injury and this, can be conceived as quite 

 possibly occurring from dry infected material blowing about or 

 from worms gaining access to the leaf bases of young trees from 

 the soil. There is a large amount of detail work remaining to be 

 done with regard to the resistance of the worms to dryness and to 

 chemical agents, to their distribution and longevity in the soil and 

 other matters. This Avork is of an obvious kind, and, given the 

 opportunity there is every prospect of approaching to a fairly com- 

 plete knowledge of the disease within a reasonably short time. 



" It is clear that the onlv hope of control lies in prevention and 

 not cure and the bigger practical difficulty is going to be the dis- 

 position of the vast amount of infested material which the dying- 

 trees contain." 



T. F. C. 



