14-:! 



THE AGEieULTUEAL NEWS. 



May 1, 1909.- 



LEf< BALAIS DE"'*^OBCIERE DU CACAOYER 

 FROVOQUESPARCOEtETOTRTCHUMLUXIFICUM. 

 Vav le ] )r. C. J. J. van Vlall and A. W. Drost. ReiiiinUd 

 from tlic Ri-ciii'il dcs Tian^n.t: hut-.ini'/ues, JVeerlandais. 



Although the ' Witfch Broom' disease of the cacao 

 luis till recently been coriflned to the mainland of 8outh 

 America, yet of late, reports^have been circulated that it has 

 reached the islands of Cuba' and San Domingo. This makes 

 it of considerable importance that all cacao planters should 

 have a sound knowledge of the principal symptoms of the 

 disease and the methods of treatment, so that they may be 

 in a position to take the heccssary steps, should their own 

 plantations be attacked. . , ^ 



A valuable .and complete account of 'witch broom' 

 disease has recently been .jpublished by Dr. \ an Hall and 

 A. W. Drost, of the Department of Agriculture of Dutch 

 Guiana, under the above title. According to these authors, 

 the losses that thexacao industry of Surinam has suffered 

 from this tiauble have been most serious. As a result, the 

 exports of cacao ii'om the colony declined gradually from 

 38,600 bags (each of 100 kilograms) in 1S99 to 8,540 bags 

 in 1904. In 1905 and 1906 the shipments were 16,818 

 and 14,806 bags respectively. 



As will . be seen, 1 904 was the worst . year for the 

 disease, which has becomH.kss severe of late, though the 

 authors- of the paper in cjuestion cannot hold out any hopes 

 of its complete disappearance. They suggest rather, that a 

 condition will be reached in which' the damage caused by the 

 disease will .become approximately constant for each year. 



The symptoms of the disease are threefold : First, there 

 is the appearance of the so-called 'witch brooms.' These are 

 YOung branches which become swollen and remain green, 

 |>roducing many lateral br:-mches of erect habit, and bearing 

 41 few small leaves whose stipules do not fall oft'. These 

 ■' witch brooms' quickly dry, up and fall oft', leaving scars which 

 do not heal well, and so afford a good means of entry for 

 other parasitic fungi, whicli may ultimately kill the trees. 



Secondly, there is the ' hardening ' of the fruit somewhat 

 similar to ' l^lack rod,'bUjy.iistinguisiied from it by the fact 

 ihat the whole of the fruit hardens, and further the stalk 

 often becomes swollen. 



The third symptom is, the 'radiating inflorescence' con- 

 sisting of very numerous How.ers ou the same cushion .stand- 

 ing erect and sometimes, interspersed with vegetative 

 iiranches. These flowers rarely if ever bear fruit, 

 ; The fungus cau.sing,.the disease is a new species of 

 jColletotrichum, to which the name CoUc.totrirlnim linijicum 

 lias been given. It attacks the young buds as soon as they 

 (begin to grow. Its mycelium and s])ores may sometimes be 

 found, more especially at tlie end of the wet season, at the 

 fcase of the ' witch brooms ' and on 'the hardened fruits. It 

 is stated that it does not attack any of the species of trees 

 commonly used in cacao jilantations for shade purposes. 



The authors found, as ti^t; rcsidt of numerous e.vperiments, 

 that conditions of soil, such as its chemical nature and water 



content, were entirely without effect on the disease ; and also 

 that the presence or absence of shade was almost or entirely 

 unimportant in combating the disease. As this is .so, it 

 was found imiiossible to assist the trees to recover 

 by improved drainage or artificial manures. Spra3ing 

 was also found to be of very- little value since the density of 

 the foliage prevented the solution from reaching the whol^ 6f 

 the leaves and budS; Consequently the only course left was 

 to remove all the diseased parts. 



The measurofi jecoramended appear extremely drastic, 

 but they have met with complete success in the experimental 

 work that has so |ii,r been done. All the vegetative parts of 

 the trees affected were removed, leaving only the trunk and 

 main branches standing. This was done while the tree was 

 passing through a resting period, which, in Surinam, was in 

 the month of September, about the end of the dry season. 

 Care was taken to leave the trees as symmetrical as possible, 

 and all the wounds .were tarred over. All the diseased parts 

 were collected and burnt. After this, the trunks were 

 thoroughly sprayed with Bordeaux mixture, followed a weelc 

 or so later by a further spraying with copper sulphate solutiou,. 

 Six months later tjhe trees had reformed new, healthy- crowns, 

 and at the end of insighteen months were bearing again. It was 

 expected that at the end of two seasons the trees would oncg 

 more give an average crop, and would have compleielj* 

 recovered from the effects of the disease. 



When reajipetu'ance of the trouble took place, the dis- 

 eased part was cut out, a small portion of the mother brancli 

 being removed ati the same time, and the wound careful!-y 

 tarred. By these. rpeans the authors have been able to keep- 

 the disease well in.aheck, especially as infection spreads very 

 slowly, and does ^lot appear to be affected by the direction 

 of the jirevailing winds. 



XOTES UX DOM IMC A AX !> JllX'fs T(> 

 JXTKXDIXG S4;f TIERS. Price 6(/. 



With the objgot of attracting attention to the undevelop- 

 ed agricultural iij;aources of Dominica, and giving reliable 

 information to intending settlers, a pamphlet under the above 

 title was prepared in 190o by Mr. (now Sir) H. Hesketh 

 Bell, then Adniinistrator of the island. As this has been for 

 some time out of print, it was decided to issue a new and ui>- 

 to-date edition. The task of revision and enlargement was 

 undertaken by the.JIon. Douglas Young, C.M.G., the preseut 

 Adnunistrator v->f Dominica, who, as the title-page states has 

 received the assistance of the Agricultural and Commercial 

 Society, and the ;J?isinters' Association, of I^ominica, and of 

 the Officers of thejmporial Department of Agriculture. The 

 result of this collaboration is an attractively got up and well 

 illustrated pamphlet, comprising in ali rather more than 

 fifty pages. f^- 



This contains Jull jjarticulars as to present conditions in 

 Dominica — climatic, industrial, agricultural and social — and 

 gives adequate information on all points of interest to person.s 

 who may be thinking of settling in the island. The various 

 agricultural crops, such as cacao, limes, oranges, and spices, that 

 are grown in the i§knd are discussed, and a detailed estimate 

 is given as to the cost of taking uj) an estate of (. rown lands, 

 clearing, planting, building a house and necessary out- 

 buildings, and the' expense of living before a return can be 

 expected. British. , .settlers who propose to take up and 

 develop land in pominica should j)Ossess a capital of about 

 £.3,000. 



The final twenty pages of the pami)hlet give valuable 

 details in regard ,to the various timbers of Dominica and 

 the uses for which they arc suitable. 



