274 



THE AGRICULTUEAL NEWS. 



September 5, 1908. 



Branches frequently die thruugh having become 'ringed,' 

 while not Hnconnmonly whole trees are killed, especially 

 when the diseased area is near the surface of the 

 ground. 



In plantations where canker has hecoine established, 

 remedial measures should be thoroughly carried out. 

 Dekid trees and all dead branches should be remove<l 

 and burned. Where canker spots exist on branches and 

 sterns, the diseased bark and wood should be cut away 

 with a sharp knife, and afterwards burned. It is 

 important that all the wounds thus causeil, and all other 

 wounds on cacao trees in the neighbourhood should be 

 cleaned and thoroughly dressed with tar. or some 

 other similar fungus-proof dressing. 



Root disease attacks the roots of cacao trees, as 

 well as of pois dou.x, bread-fruit, bread nut, avocado 

 pear, etc. If allowed to run its course unchecked, the 

 disease causes the death of the affected trees. As in 

 the case of canker, all trees in the cacao plantation that 

 have died of the disease should be removed and burned, 

 and special care should be taken to (wtraet every portion 

 of the roots. 



When an area of cacao is seen to be affected, 

 a. circumscribing trench should be dug to isolate it from 

 the remainder of the field. The most badly diseased trees 

 should be removed, all the roots being dugout. In the 

 case of other trees less badly affected, the roots should be 

 laid bare by the removal of the soil, and all diseased 

 roots be cut out and burned. Lime should then be 

 applied around the roots of the tree, and after the soil 

 has been replaced, and the whole of the infected area 

 well forked, a good application of (juick lime should be 

 broadcasted over the land. The health of the trees 

 will be promoted by dressings of pen manure, and by 

 mulchings given some time later, and in the follow- 

 ing year a second application of lime, in about half the 

 quantity, should be given. 



The susceptil)ility of bread-fruit, breacl nut .ind 

 other trees to attacks of the fungus responsible for I'oot 

 disease of cacao would suggest that these trees should 

 be excluded from all new plantations of cacao. All 

 such trees, in old established orchards, which show any 

 signs of disease should be taken out and burned, and 

 when any are cut down care should be taken to extract 

 and destroy all the roots. 



Several other fungus diseases are dealt with, .and 

 methods of treatment indicated. Among these discast's 

 may be mentioned those known as die-back, Lasiodiplo- 

 dia, pink disease, witch broom, brown rot and black rot 

 of pods, scabby pod, etc. Die-back has been noticeable 



particularly in St. Lucia, but it can be practically 

 eradicated by high cultivation, manuring, suitable 

 pruning, etc. ' Pink disease ' is known in Dominica 

 and has also been noticed in St. Luci;i. It does not 

 appear to be serious in itself but since its presence 

 causes cracks in the branches of affected trees, by 

 which the spores of other fungi may gain entrance, it 

 may easily be the forerunner of more serious diseases. 



Both the brown rot and the black rot of pods have 

 been responsible for a good deal of damage among 

 cacao plantations in various islands. Brown rot is <lue 

 to the same fungus — Diflo'lin rdaioicohi — which 

 causes the die-back disease of the stem. The gather- 

 ing of diseased pods, together with the collection of 

 husks and shells, and their subsequent burial with 

 lime, is a measure that should receive first attention on 

 the appearance of either brown or black rot, since 

 experience has showia that this is a valuable means of 

 checking the disease. 



During the past ten years much usefid work has 

 been done in the West Indies in investigating the 

 fungus diseases of cacao, and the best methods of treat- 

 ment. In this, the successive Mycologists attached to 

 the Imperial Department of Agriculture have been 

 largely instrumental, while officers of the Department 

 stationed in the several cacao-growing islands have also 

 given useful assistance. Recently Mr. O. W. Barrett 

 of the United States Department of Agriculture was 

 specially engaged by the Government of Trinidad for 

 a period of five months studying the fungus diseases 

 affecting cacao in that colony, and he has issued several 

 reports. With the fuller knowledge of the subject, 

 acquired as the result of the above work, it may be 

 stateil that practically all the ditferent fungus diseases 

 of cacao are amenable to treatment, and by the adoption 

 of proper methods may rapidly be reduced to.i minimum. 



The attention of planters is particularly drawn to 

 the latter section of the pamphlet which deals with the 

 Sanitation of Cacao Orchards, since in it they will find 

 a good deal of matter well worthy of their considera- 

 tion. The importance of thorough and careful cultiva- 

 tion as a means of warding off disi'ases is emphasized, 

 and it is pointed out that expenditure on tillage, 

 dniinago, and judicious m.anuring is repaid by t,he 

 improved condition of the trees, and liy the increased 

 yield. Various cultural and other operations, such 

 ,is pruning, the treatment of wounds, protection 

 from wind, provision of shade, etc. are also briefiy 

 discussed in so far as they may hare an infiuence in 

 maintaining the health of the trees and in preventing 

 the appearance and spread of disease. 



