192 TRINIDAD AND TOBAGO BULLETIN. [XVIII. 4. 



lightly infected trees, and indirectly by preventing the formation of new 

 centres of distribution, save very many more. All that is needed is to 

 have the lower branches pruned sufficiently for access to the trunk, a 

 couple of labourers to go on ahead and clear away weeds and earth for 

 a foot or so around the junction of roots and stem, preferably using 

 their hands or a blunt instrmnent to avoid wounding the bark, and 

 then to make a few minutes' investigation of each tree so prepared. 

 In addition to saving trees, such a system enables the hopeless cases to 

 be detected long before they otherwise would be, and makes it possible 

 to deal promptly with them. One is justified here in being insistent 

 and saying that in ever^' clearing in which the disease has become 

 established, such an inspection ought to be made at least twice a year. 

 It is after all a mild proposal. 



The principles of the actual treatment required are two in number, 

 and very simple : (a) complete excision of diseased tissues ; (b) exposure 

 as complete as possible of the affected part and its surroundings to freely 

 circulating air, with the object of making the conditions too dry for the 

 fungus to exist. In operating it must be remembered that after the 

 early stages the fungus penetrates wood as well ai; bark. It is the 

 drastic surgery made necessary by this fact, and the propensity of the 

 fungus for lateral spread in the outer zone of roots, that make the saving 

 of cases at all advanced so hopeless. Commonly in such a case a great 

 part of the root system has to be cut away, and the roots severed in the 

 operation and left behind give every opportunity for the disease to 

 re-assert itself. 



The cases which repay treatment are those arising from surface 

 infection, in which on inspection the local nature of the infestation 

 ai:)pears to be clearly defined. Severed roots should as far as possible be 

 removed ; cut surfaces should be cleanly trimmed and dressed with 

 paint ; excavations made to get at the seat of injury should be left open. 

 It should be hardly necessary to say that the material removed must be 

 carefully disposed of. These directions may give rise to an exaggerated 



idea of the elaborateness of the treatment required 



but in many cases a few cuts with a sharp knife will save a tree from 

 an infection which would have meant its certain death. 



Where the disease has been detected advancing along one or more 



large roots but has not reached the collar, and it is desired to give the 



tree a chance of recovery, then after the diseased roots have been cut 



away, as much soil as possible should be dug out about the junction of 



the main roots and as far back as they can be conveniently followed, 



leaving the tree more or less on stilts as it were. This prevents the 



crossing over of the fungus at or near the collar, and may very 



considerably delay the loss of the tree, but if the fungus, as is probable, 



exists on the outer roots, it will in time get round in that region and 



come up each of the main roots in turn as far as the point to which it 



has been bared. It is not a measure to be recommended. It is better 



to have the tree out and be rid of the fungus, but the temptation to get 



an additional crop or two from some specially fine tree is sometimes 



hardly to be resisted. 



