1919.] BOOT DISEASE OF CACAO IN TBINIDAD. 191 



IN CACAO PLANTATIONS. There are probably few managers of cacao 

 plantations who would nowadays plant breadfruit or avocado trees 

 through their fields. The idea of the more economically minded of the 

 old planters seems to have been that since shade trees were to be grown, 

 they might as well be such as would give something in the way of food 

 in return for the room they occupied. The modern idea of the uaauurial 

 function of shade trees leads to a preference for leguminous trees, and 

 justifies the more orthodox tradition which led to the planting of immor- 

 telles. Where avocado and breadfruit trees are already established, the 

 planter who has learnt respect for the root disease has two courses open 

 to him. The one is to take the utmost care of such trees, to prune out 

 dead branches, to avoid injuries to thu roots and generally to try to 

 preserve them in health as long as possible ; the other is to take them 

 out as occasion offers, removing the stumps, and following out and 

 removing every root that can be got at. This is usually difficult because 

 of the adjoining cacao trees ; where the trees to be dealt with are large, 

 it becomes formidable. The easy course is to cut down or ring the 

 the trees, and leave the roots to rot, but that way trouble lies. It does 

 not always happen, but striking, one might say startling, cases have 

 been seen where the cutting down of an avocado or breadfruio in the 

 cacao, or a pois-doux by the roadside has led to the appearance of the 

 disease in places from which it has thought to be far removed. These 

 three trees are the chief victims, but there is none that can be 

 considered to be really safe. It should be the settled policy of cacao 

 planters in wet districts to leave no woody material to rot in the soil if 

 it can possibly be avoided. Where there is deep shade and high 

 humidity, any vegetable matter used as mulch may be a source of 

 danger, though one that may have to be risked in view of manurial 

 requirements. The more careful and prompt the attention that is given 

 to any appearance of the disease on the plantation the less will the risks 

 of this nature be. 



With regard to wind-breaks ; where experience has shown that there 

 is danger of disease arising, it is advisable to keep them as free as 

 possible from undergrowth, and to scrape away any accumulations of 

 leaves or other material from hollows or other sheltered places. This 

 might be used as mulch in dry places or preferably, if there is a pen near, 

 for the making of pen manure. 



Treatment. 

 In a recent pamphlet (1915) the writer has stated that attempts to 

 cure infected trees may be put aside as in most cases hopeless and in 

 the remainder doubtful, and as involving so much skilful surgery as 

 to make them impracticable on any but the smallest scale. Addressed 

 to the planter as he has usually been found, concerned with matters of 

 primary urgency and with very inadequate assistance, the words may 

 still stand. As regards trees with deep-seated or well-estabUshed 

 infections there is indeed no more to be said. But actual experience, as 

 illustrated in the cases previously detailed, has shown that in fields in 

 which the disease is established and surface infection is taking plains, 

 an examination of the trees, involving no more than an initial clearing 

 and periodic inspection of the crown and collar, will directly s ive many 



