146 



THE AGRICULTURAL NEWS 



May 19, 1917. 



effects of treatment, like manuring, in terms of yield. 

 Neglect to appreciate this principle is one of the 

 reasons why the manurial experiments with cacao and 

 cotton have often given such apparently inconclusive 

 results. 



As already intimated, yield in the case of the 

 second group of crops which give vegetative produce is 

 generally of a more constant character. Once the crop 

 has become established there is no specially critical 

 period. Nitrogenous manuring is general!}' essential, 

 and general development, which is the thing aimed at, 

 is almost entirely regulated by moisture conditions, 

 and nitrogenous manures. In fact, the most impor- 

 tant general difference between the two classes lies 

 in the cumulative effect of nitrogenous manur- 

 ing on yield in vegetative crops. And in con- 

 nexion with yield, it will be realized that in the 

 case of vegetative produce the collection of the 

 material is not such a critical affair as it is with the 

 more perishable produce of the fruit order. There are 

 exceptions, as in the case of tobacco, but generally 

 speaking this observation holds good. 



An important way in which crops yielding 

 vegetative produce differ from fruit-producing crops is 

 in their composition. There is generally a marked 

 preponderance of some constituent which gives to the 

 crop its particular economic value. Thus in the 

 sugar-cane there is a high percentage of sugar, in the 

 yam a high percentage of starch, and in the rubber 

 tree there are produced exceptional quantities of nitro- 

 genous latex. Generally speaking crops yielding 

 vegetative produce show a much wider variation in 

 chemical composition compared mth their wild pro- 

 totypes. The difference in the case of fr\iit-producing 

 crops is more a question of quality than one of 

 proximate composition. Rubber, of course, is an excep- 

 tion, plantation and wild Hevea being very similar. 

 But it must be remembered that the cultivation of 

 rubber is a very recent introduction to tropical agricul- 

 ture, and there is little doubt that in time seed selec- 

 tion will cause cultivated Hevea to exhibit marked 

 differences from the tree growing in the wild state. 



There is no general distinction between the two 

 groups of tropical crops in regard to methods of propa- 

 gation. Vegetative and sexual propagation is practised 

 in both groups, though perhaps vegetative methods 

 are used rather more in the second than in the 

 first. In the case of crops producing fruit there 

 appears to be no instance where the employ- 

 ment of seed is entirely absent from the method 

 of propagation, for even in the case of grafted 



citrus and cacao, seed has to be used in order to raise 

 the stock. Similarly in the second group, the 

 production of seedling sugar-canes implies fertilization 

 and seed production in the first instance. 



As regards pests and diseases, it would appear 

 that crops yielding fruit products are in general 

 more susceptible than crops yielding vegetative pro- 

 duce. Cotton is very subject to pests and diseases, 

 the chief West Indian maladies being bacterial 

 and internal boll diseases, and the principal pest the 

 cotton worm. Generally speaking it is the fruit of 

 tb.ese crops that is especially susceptible to disease. 

 The fruits of most cultivated crops are so constituted as 

 to afford an excellent medium for the growth of a para- 

 sitic organism: this is particularly well seen in the 

 case of cacao and cotton. The vegetative tissues 

 are not so easily infected, and they furnish a less con- 

 genial medium fOr the parasite's development. 



There are other aspects in respect of which the 

 two groups of tropical crops might be compared, but 

 enough has been said to indicate the principal ways in 

 which they tend to differ. It is important to note that 

 in one respect — soil and climatic requirements — the 

 classification into two groups breaks down. Each 

 crop possesses a marked individuality in regard to soil 

 and climate, and this is one of the principal reasons 

 why in practice it is impossible to do other than study 

 tropical crops individually. It is nevertheless sug- 

 gestive sometimes to regard things from a new stand- 

 point, and it is with this idea that we have attempted 

 in this article to compare tropical crops on the basis of 

 fruit and vegetative produce, respectively. 



AREA UNDER DIFFERENT VARIETIES 



OF SUGAR-CANE IN ANTIGUA 



AND ST. KITTS. 



For many years past it has been usual to include in the 

 Report on Sugar- cane Experiments in the Leeward Islands 

 a tabulated statement showing the area occupied by the 

 ditferent varieties of cane under cultivation in Antigua and 

 St. Kitts for reaping in the season subsequent to that reported 

 on. 



A return of this description affords a means of following 

 the manner in which the cultivation of the different varieties 

 available for planting is being exrended in the different cane- 

 growing areas. It therefore constitutes a valuable adjunct to 

 these experiments, since it offers a method of ascertiiniii-; 

 indirectly how far the results of the experiments are borne 

 out by the experience of planters. 



Such a comparison has again been compiled in respect of 

 the areas under cane varieties in Antigua and St. Kitts due 

 for reaping in the crop of 1917. 



Considering first of all the position in relation to Antigua, 

 we find that the total area returned as under cultivation in 

 canes on estates amounts to 9,960 acres in round numbers. 

 This represents a decrease of 40-5 acres when compared with 



