Vol. XVII. No. 411. 



THE AGRICULTURAL NEWS. 



2.3 



the trees when planted 14 x 14 feet are, according to JIalayan 

 experience, planted too close. Thin, overshaded trees will 

 neither give a good yield of latex nor make a healthy birk 

 renewal. The committee recommends the cutting out of 

 the poorer trees in such cases, even if the resulting appear- 

 ance of the field be irregular. It is advisable, in the light 

 of kuowledge acquired by later experience, to plant Ilerea. 

 in conformity with the best practice in Malaya, at 20 x 20 

 feet apart. 



At such distances, seeing that the trees take several 

 years to cover the ground, the loss of soil through wash may 

 be very great, pirticularly if 'clean- weeding' is practised. 

 It is recommended that a cover crop be grown, and Caiuvaiin, 

 endformis (sword bean or horse bean) is suggested as emi- 

 nently suitable, for the following reason?. Like most legumi- 

 nous crops it adds nitrogen to the soil. Unlike other legumi- 

 nous cover crops it is tolerant of a moderate amount of shade. 

 It has very little disposition to climb, a good characteristic 

 when planted under young trees. It makes a dense growth 

 2 to 3 feet high. It prevents wash. Its heivy crops of 

 beans, maturing in from four to six months, provide a whole- 

 some and palatable human food. 



Hev.a seeras to suit most of the soils in Trinidad and 

 Tobago, with the exception of the Naparima district, showing 

 an apparently good growth even in one of the driest districts 

 of the island of Trinidad, thus indicating that a heavy 

 rainfall is not absolutely essential to its cultivation, 

 provided that the subsoil is such as to bs easily penetrated 

 to a considerable depth by the roots of the trees. 



After discussing various methods of tapping, the report 

 seems to recommend the method known as the 'single quarter 

 cut,' for the following reasons: (") it.s extreme simplicity, 

 (A) that a man can tap a greater number of trees per day than 

 b)- other methods, (c) that instead of four, a period of seven, 

 or even eight years may be allowed before it is necessary to 

 tap renewed bark, {d) that it reduces the amount of 'scrap' 

 rubber to a minimum. 



Valuable data as to cost of production and profit per 

 acre were supplied to the committee from two of the largest 

 estates. In one case the cost of production per acre was 

 given as $86"14, and the rubber produced sold at .jOc. per ft)., 

 giving .f 147 per acre, leaving a net profit of 860'86 per acre. 

 In the othttr case the profit was estimated at $61 27 per acre, 

 a strikingly similar result compared with the first. 



With respect to tapping intervals, the committee seems 

 to agree with the conclusions reached after experiments at 

 the St. Clair Experiment Station by Mr. W. G. Freeman, 

 Acting Director of Agriculture, that tapping at intervals of 

 four days will probably be the most profitable in Trinidad. 



As to the care of trees, the report emphasizes the very 

 great precaution that must be taken to guard the bark from 

 injury, and to dress any accidental wounds with a mixture of 

 crude oil and tar, both to help the wounds to hea', and to 

 protect them from fungi and boring insects. 



Referring to the practice of growing other perennial 

 crops along with Ilevea, the committee is strongly averse to 

 cacao, on the ground that it only comes into full bearing 

 when the Herea shade becomes so heavy that the cacao has 

 to be cut out. Besides, /'ki/lnpht/iom, a widely spread 

 fungus disease of cacao, also attacks Ilevea. The first 

 objection to cacao also applies to lime trees as an intercrop. 

 Coffea rn/iusta is regarded as perhaps the most suitable crop 

 for the purpose, if an intercrop is to be grown, as it 

 comes into full biaring in thiee year.», and thus gives two 

 or three years' crops before it is too densely shaded by the 

 Hevea. On th^ whole, however, the report seems to conclude 

 that 'pure cultivation' of Herea is the best plan to adopt. 



With regard to Castilloa elastka (Central American 

 rubber) which was introduced into Trinidad in 18S0,the com- 

 mittee advises against any extension of its cultivation, although 

 it was so strongly recommended earlier, and was largely 

 planted. In fact it has proved so much of a failure that 

 hundreds of Castilhia trees are being cut down for more 

 profitable cultivations. 



Nor is the committee able to advise any further exten- 

 sion of the cultivation of Funtumia, elaslica (African rubber), 

 especially as satisfactory growth and yield are being obtained 

 from Uevea even in the drier districts of the island, to 

 which it was thought that Funtumia would be specially 

 suited. 



The report contains very valuable reeommendatious aa 

 to preparing the rubber obtained from the three species dealt 

 with, so as to place it on the market in the best condition; 

 these are hardly within the scope of this review. 



A summary of recommendations closes the report, to 

 which attention has already been drawn in Xo. 407 of thia 

 Journal. The co-operation of rubber growers is strongly 

 advised as a means of furthering the extension of the indus- 

 try, and of setting it on a sound basis. 



A most useful bibliography of literature on the subject 

 forms one of the appendices of this full and interesting report, 

 which may profitably be read by those interested in rubber 

 cultivation in the West Indies. 



PLANTS POISONOUS TO LIVE STOCK. 



The book with the above title, a review of which in Nature 

 was noticed in the A;iricultural Neirs, Vol. XVI, No. 405, 

 has recently been received at this t)ffice. The discussion 

 relating to the poisonous plants occurring in Great Britaitk 

 is very full in the book in que&tion. Some general remarks 

 however, are worth attention by those interested in live stock 

 everj'where. 



The author states that in many cases it is practically 

 impossible to come to any conclusion as to the degree of 

 toxicity of a plant, owing to the want of exact information. 

 This especially applies to the condit ons obtaining in our 

 West Indian islands, where much work remains to be done 

 in exact study of the properties of the flora. It is noticed, 

 for instance, that many plants are quite harmless, except 

 when affected by fungi, etc. 



A really poisonous plant may be defined as one, a small 

 quantity of which when eaten, induces some form of indis- 

 position with serious, or even fatal consequences, either 

 immediately or as a result of the cumulative action of the 

 toxic property. 



The action of plants on animals may be ascertained (1) 

 by observing the eft'ects in cases in which it is certain that 

 the plants in question have been eaten, or (2) by direct 

 experimental feeding of animals with the plants. The real 

 test as regards (2) would, in general, consist in a feeding trial 

 in which the suspected plant occupied a place in the ration 

 in such a quantity as might be taken in natural circumstan»es. 

 Should such a test prove negative, it may generally be held 

 that the plant is not poisonous, or only so in exceptional 

 circumstances. 



It is pointed out by the author that a number of poison- 

 fius plants have a considerable influence on the milk-yield of 

 animals which eat them, reducing it in volume, or imparting to 

 it an unpleasant flavour which renders it unfit for human 

 consumption. Even if not actually poisonous, such plants 

 must be considered harmful, as is the case with the common 

 West Indian weed, gully root (Pttiveria alliarea), which it 

 is well known, imparts a mosi unpleasant flavour to the milk 

 of cows which have eaten it. 



