Vol. XTII. No. 411. 



THE AGRICULTUIIAL NEWS. 



•27 



The yfung caterpillars pass their early stage on these weeds, 

 tunnelling into the stems, and later go to the sugar-cane. The 

 best remedy is to keep the fields clear of weeds, but this can 

 rarely be practised in Mauritius owing to shortage of labour. 

 Other methods, however, can be used, such as cutting out of 

 dead hearts, rotation of crops, and growing catch crops 

 to keep down weeds. 



It is strongly recommended in Mauritius that on no 

 account should sorghum, maize (Indian corn), or any other 

 plant related to sugar-cane be used as a catch crop, as the 

 cultivation of these crops in close proximity to the canes 

 would only serve to increase the infestation with moth borers. 



It has been found that maize can be planted in Mauritius 

 as a trap crop on definite areas, and carefully watched and 

 destroyed when the plants become well infested. Experience 

 has shown that the pink borer has so marked a preference 

 for maize that this crop can be used not only as a preventive 

 against infection, but that it even serves to check an infection 

 which may have broken out. 



The spotted borer is not as serious a pest in Mauritius 

 as the above species. The eggs are not laid merely on the 

 leaf-blades, as is the case with the West Indian species, but 

 may be laid on almost any part of the plant above ground, 

 and are consequently very difficult to find. The collec- 

 tion of egg- masses, as practised in the case of Diatraea 

 saccharalis, is of no value against the Mauritius species. The 

 measures recommended against the pink borer may aho be 

 used with this species, since it frequents graminaceous weeds 

 in the same way that the pink borer does. Both these species 

 have parasitic enemies in common. 



The white borer moth lays its eggs on the leaf-blade or 

 on the sheaths, and the young larva crawls down and enters 

 the underground portion of the shoot. It does not go 

 immediately to the centre of the plant as do the other two 

 species, but reaches the heart by ascending spirally. The 

 cutting out of dead hearts is recommended, care being taken 

 to destroy all plants so cut, since it is important to destroy 

 any eggs laid on the leaves or stem. The plant should be 

 severed well belcv the surface of the soil, and as near as 

 possible to its point of attachment with the stool. 



The brown borer as a rule only attacks cane shoots that 

 have been injured by the other borers, or stalks that are 

 diseased. It is advisable in planting not to use infested or 

 diseased cutting?. 



M. de Charmoy also gives an account of the natural 

 enemies of these borers, both parasitic and predaceous, with 

 descriptions of the species of parasites. 



•J.C.H. 



WOOD OR CANDLE NUT OIL. 



In forwarding to the Imperial Commissioner of Agricul' 

 ture for the West Indies an advance copy of a note to be 

 published in ihe last number of the Knv Bulletin h-ir 1911 , 

 the substance of which is reproduced below, Mr. A. W. 

 Hill, Assistant Director of the Koyal Botanic Gardens, Kew, 

 remarks: 'As it is probable that the demand for drying oils 

 of this particular character will increase in the future, we 

 are inclined to think that the cultivation of the tree on a large 

 scale in British dominions, and especially in the West Indies, 

 may be worthy of serious consideration. 



The special demand for ths oil yielded by the seeds of 

 Ahurites spp. is in connexion with varnishes used for 

 aeroplanes. The chief source of this type of oil is A. F^nUi, 

 the Chinese species, but owing to ditilculties of transport 

 supplies from this .source are not now readily available. 



Attempts have been mide by obtaining a number of 

 seeds of A. Fvrdii from the Botanic 'Jardens, Hong Kong 



both in 1912 and 1916, to grow this species in the Botanic 

 Gardens of several of these islands, but without success. 

 The seeds have germinated in most cases, but after some 

 time the plants have failed completely, showing that they 

 are unsuited to West Indian conditions. On the other 

 hand, A. trilo'ia grows well and fruits abundantly in most of 

 the smaller West Indian islands, notably in Nevis and 

 Dominica. It would seem advisible to experiment further 

 with systematic cultivation of this species in favourable 

 localities, in view of the opinion quoted above, and the note 

 in the Kev Bulletin, which follows: — 



'Candle nut or Indian Walnut (Aleui-iles triloba, Forst. ). 

 A tree 40 to 60 feet high; native of Polynesia and Malaya, 

 distributed by cultivation to India, Burma, Ceylon, Hong 

 Kong, Mauritius, West Indie.=, Eist Africa. 



'.\llied species A. cordata, R. Br., A. Fordii, Hema!., 

 and A. trisperma, Blanco, have been dealt with in previous 

 issues of the Bulletin. As a .source of oil the species under 

 consideration is of equal importance. The seeds contain 

 a large quantity of oil which is obtained by expression, and 

 because of its drying properties is used for mixing with 

 paints under the name of Country Walnut Oil. The kernels, 

 when dried and stuck upon a stick, are used as candles in 

 the Polynesian Islands. 



'The nuts and oil have been reported to bo edible; but 

 this is open to serious question, as considerable difference of 

 opinion exists amongst wi iters on the point. Having regard 

 to the Order {Euphorliiaceae), and the close alliance with 

 species known to be distinctly poisonous, it would be inad- 

 visable to rely on the oil for table use; it cin be readily 

 dispensed with for this purpose since we have so mmy more 

 oils of proved quality and that come neirer the standard of 

 ■'olive oil'' The nuts might pass locilly for food, but only 

 when quite fresh. According to the Ti apical Agiiculturiit, 

 "the half-ripe fruits with salt have a delicate flavour, but the 

 ripe fruits are unwholesome and only eaten in time of scarcity. 

 This uncertain character is borne out by the variation in 

 analyses of the oil, some comparisons of which are given in 

 C'Aonial Reports, No. 8S (Misc. Series) pp. 419-50. The oil, 

 however, is of growing imp' irtancebecauseof the industrial uses 

 to which it may be put, and the above report bears out tlie 

 opinion already referred to as to the drying properties, typified 

 by linseed oil, and recommends it "for the manufacture of 

 .sof tsoap, the preparation of oil varnishes, paints and linoleum, 

 and for other simdar purposes to which oils of this class are 

 applied industrially." Further, the value (1906) for nuts 

 in Europe is given at X12 to £13 per ton, and of the oil 

 (1911) at £28 to £30 per ton, with the residual cake at 

 £1 lO-s. to £2 per ton— suggested for fertilizing. The 

 percentage of oil in the kernels has been variously quoted 

 at from 50 to 68, and where the oil cannot be expressed 

 locally it is recommended that only the kernels be exported 

 to this country. An analysis of the kernels from one 

 of the Pacific Islands is recorded in the Agriruhural 

 News, Barbados, October 6, 1906. In Ceylon the nuts 

 are known as "Kekuna", and an important paper entitled 

 "Candle Nut (Kekuna) Oil as an Industry" is published in the 

 Tropical Agriculturist, \o\. XLVIII, May 1917, pp. 300-2 

 urging its cultivation, which, as the tree grows so freely, 

 .should not be attended with any ditficulty. Planting 25 to 

 30 feet apart in protected situations up to 2,600 feet above 

 sealevel is recommended, and the tree is said to bear at the 

 end of the .second year.' 



It may be noted that an account of the efl'orts to 

 introduce A. Fordii into the West Indies, and of the value 

 of its nuts as a source of drying oil, appeared in the Aijri- 

 cultural ytws, Vol. XII, p. 403. 



