66 



THE AGRICULTURAL NEWS. 



March 2, 1912, 



these are unknown, so far, in the West Indies. Atten- 

 tion was, however, drawn to the fact that a parasite of 

 the pest has been discovered recently, in pear orchards, 

 in California, the parasitism amounting, in some cases, 

 to as much as 70 per cent.; this is to be introduced 

 into the West Indies, by way of Trinidad, and the fact 

 that the host belongs to the same species ofthrips as 

 is injurious in this part of the world renders ic the 

 moi-e hopeful that it will prove to be a successful means 

 of control. Under present conditions, in the West 

 Indies, evidence points to the fact that cacao thrips is 

 best kept in check by the adoption (jf proper methods 

 of cultivation and manuring, to the end ihat the plants 

 may be maintained in a state of good health. 



Discussion relating to grafted cacao led to the 

 consideration of the possibility and utility of making 

 crosses between different varieties, in order to obtain 

 forms possessing the best qualities of various kinds. 

 It was stated that, in Dominica, hybrids had been 

 obtained, and that it was intended to proceed further 

 with the work of crossing. A niatter of importance and 

 utility in this connexion is that, when a desirable type 

 is obtained in such a manner, it can be quickly perpet- 

 uated by grafting, with reasonable certainty that 

 all the new individuals will possess the characteristics 

 for which that type has been produced. Dealing, fur- 

 ther, with the natural outcome of such work, namely 

 the eventual acquirement of plantations containing 

 trees belonging to one variety, although the advantages 

 of the possession of uniform cultivations were admitted, 

 attention was drawn to the greater chance that these 

 possess of being destroyed by an epidemic of disease, as 

 compared with that to which a mixed cultivation, possi- 

 bly containing immune types, is subjected. A further 

 advantage of mixed cultivations was also suggested, 

 namely the circumstance that, in these, flowering and 

 fruit-bearing take place at different periods, in the case 

 of the various types, so that an economy in the matter 

 of drying space is ■ effected, because the coming to 

 maturity of the pods takes place during a lengthened 

 period. 



Another matter connected with cacao cultivation 

 had relation to the choice of types for planting under 

 different conditions. In regard to this, it is obvious 

 that the question awaiting solution is whether fine 

 quality of the cacao, j^roductivity of the plants, or 

 resistance to disease, is the property that it is most 

 desirable to acquire. A partial answer has been found, 

 in experience, in the circumstance that some condi- 

 tions have pointed to the advantage of employing low- 



lying lands for raising the commoner and more produc- 

 tive varieties. JFrom what has been said, however, it 

 is evident that the aim of future work will be to obtain 

 forms possessing two, or even all three, of these emi- 

 nently useful characteristics. 



At the session for the discussion of matters relat- 

 ing to sugar, before the regular business was taken up, 

 a resolution was brought forward, with the leave of the 

 President of the.Couference, expressing dismay at the 

 threatened withdrawal of Great Britain from the 

 Brussels Sugar Convention, and this was carried with 

 acclamation. After the reading of papers dealing with 

 experiments with sugai'-cane, one of the first matters 

 receiving attention was the fact of the inapplicability of 

 Mendelian principles in the production of varieties, at 

 the present time. In further discussion, the subject of 

 the failure of the Bourbon cane came under notice, and 

 the meeting was reminded that more than one variety 

 existed, which was included under this name; while the 

 interesting suggestion was made that the true Bour- 

 bon had maintained its good properties for so long 

 a period because it was being reproduced, from time to 

 time, by seed. In any case, practical evidence was 

 brought forward that there existed the certainty, in 

 many instances, .that the yield of sugar had not de- 

 creased, from the old returns, under the cultivation of 

 seedling canes. 



Several papers were read which had relation to 

 the subject of plapt pests and diseases, and the ques- 

 tion arose as to the possible existence of the danger 

 that fungi that had been disseminated in districts, for 

 the piirpose of controlling scale insects and other insect 

 pests, may themselves become dangerous to plants. 

 No evidence has been found, in any case, to show that 

 there is such a danger. One of the most interesting 

 matters that came forward, in relation to such control, 

 was the degree to which the fungus Cephalosporitim 

 lecanii had appeared to lessen the numbers of the mango 

 shield scale in Grenada: the scale had disappeared from 

 about three-tpiarters of the existing trees, since it had 

 been disseminated from certain districts where it was 

 doing its work as a parasite, and there is little doubt 

 that the disappearance is due to the presence of the fun- 

 gus; thus a cheap and effective method is in operation for 

 the control of the mango shield scale, in that island. As 

 was pointed out by the President, this kind of control 

 of insect pests is a matter of recent development — 

 a development which marks the existence of new lines 

 of work, in the West Indies as well as other parts of 

 the world. 



