Vol. XIII. No. 317. 



THE AGRICULTURAL NEWS. 



203 



Navire estate, we pointed out to M. Cistelli, Professor of 

 Agriculture, the possibility of making an emulsion of carbon 

 bisulphide with alcohol. Carbon bisulphide is soluble, part 

 for part, in pure alcohol. On pouring this solution into 

 an appropriate quantity of water, and shaking it briskly, 

 a sort of emulsion is obtained, representing fairly exactly that 

 produced by the special pump employed at Case Navire. 



AVe know from information given by M. Castelli and by 

 the Department of Agriculture that this mode of procedure 

 was tried with success by several proprietors. 



But the emulsion with alcohol presents certain inconve- 

 niences We propose to replace it by another kind — an 

 emulsion made with oil, which is much more practical, still 

 less expensive, and very easy to use. It is prepared as 

 follows;. — 



1. Mix together equal volumes of carbon bisulphide 

 and vegetable oil of the lowest quality obtainable (castor 

 oil or cotton setd oil). The mixture is easily made and 

 forms a .sort of stock solution from which one may make 

 emulsions of the required strength. 



2. Take the required quantity of water and make it 

 alkaline by the addition of about H oz. of carbonate of soda 

 (washing soda) to each gallon. 



3. Into the quantity of water to be employed per plant 

 pour the required do.se of the mixture of carbon bisulphide 

 and oil. 



The period of treatment is preferably during the months 

 of September and October for cacao, and those which follow 

 on the dry season in the case of coffee. In the one case as in 

 the other, one catches the eel-worms and the Diaprepes 

 larvae at the commencement of their development, before 

 they have been able to commit their depredations. These 

 times coincide moreover with those periods when on all the 

 plantations it is easy to store a sutticiency of rain-water 

 near enough to the scene of operations to render the carrying 

 out of the treatment as economical as possible. Although 

 the rainy season is recommended as the time of treatment, 

 it does not follow that one should choose rainy weather to 

 make the application. It is, on the contrary, preferable to 

 work in fine weather in order that the dry soil will rapidly 

 absorb the emulsion. Treatment carried out in rainy 

 weather means trouble thrown away. 



The appropriate dose and the method to be employed 

 vary with the parasite to be destroyed and with the nature 

 of the plant attacked. According to M. Thierry one slionld 

 work as follow: 



Arabian coffee. — The parasite to be feared and to be 

 destroyed is the eel-worm. The emulsion should contain 

 1 part of carbon bisulphide or 2 parts of the stock 

 solution to 1,000 of water, that is to say J-oz. of the stock 

 solution to each gallon of water. With this soak round the 

 foot of the tree within a radius of 16 inches, after having 

 stirred the soil to facilitate the penetration of the liquid. 

 A sufficient amount should be used to impregnate the soil 

 to a depth of i inches. It requires 4 to 10 pints of emulsion 

 per tree according to the age of the plant. 



Cacao. — The emulsion should be much stronger. A 

 strength of 1 part carbon bisulphide per 1,000 is not 

 sufficient r to kill Diaprepes; double that strength, namely 

 -g-oz. of the stock solution per gallon of water is required. 



The larvae of Diaprepes are destructive throughout the 

 districts with alluvial soils and the treatment applied for that 

 larva serves at the same time to destroy the root disease, for 

 which a strength of 1 per 1,000 appears to sufK:e. 



For application of the emulsion to cacao, make round the 

 stem of the tree a trench 6 to 8 inches in breadth and 2 to 

 i inches in depth, according a.s to whether the primary roots 



are found near to, or distant from, the surface. No attempt 

 should be made to uncover the lateral roots, so as to avoid 

 wounding or barking them. After loosening the soil at the 

 bottom of the trench, fill the latter with the emulsion of 

 a strength of 4 parts of stock .solution per 1,000 of water, 

 using 4 to 10 pints according to the size and age of the 

 plant. As Much as 18 pints may be used for the larger 

 trees if sufficient water to go round is available. 



In Barbados, carbon bisulphide (Fumi Brand) is obtain- 

 able in .5gallon drums at 1.5c. per Dt). Crude cotton seed 

 oil may be obtained at present at about 75c. per imperial 

 gallon. Washing soda is sold at 4c. per lb. Taking the 

 quantity of emulsion used per tree at 1 gallon, the cost is 

 as follows: — 



•6 oz. carbon bisulphide at 15c. per tt). -Gc. 



r-5 " carbonate of soda at 4c. per t). -IQc. 



■6 " cotton seed oil at 7-5c. per gal. -280. 



The cost per adult cacao tree using the stronger emulsion 

 is thus a little over Ic. 



To sum up, the carbon bisulphide destroys white 

 grubs, and eel-worms, and cures root disease, the principal 

 causes of the death of the trees. In addition, it hag the 

 faculty of sterilizing the soil, that is to say, it destroys the 

 toxins which have a prejudicial effect on vegetation. This 

 fact alone leads to results which justify its use. 



It would be wrong to consider the treatment as resting 

 on a purely theoretical argument. It is by its application 

 as a preventive during many consecutive years that 

 M. Thierry has saved his cacao plantations, which were 

 ravaged by the larva of Diaprepes. The area thus cultivated, 

 treated, and maintained in prosperity enables it to be said 

 that the method is not merely one of the laboratory. 



The preventive treatment with carbon bisulphide con- 

 stitutes there not merely an occasional operation but a regu- 

 lar agricultural practice. 



EXOPHTHALMOS ESURIENS. 



In 1912, Exophtluduuis esuriens was found in St. Kitts 

 associated with root borer grubs in sugarcane in such 

 a way as to cause it to be suspected of being the parent 

 form of these grubs. Information is not yet available as 

 to the amount of injury caused by the feeding of the grub 

 of this species on the roots of lime trees. It will be seen, 

 however, from the article which appears on this page that 

 a closely related form, E.famelivus, is known to be a serious 

 pest of lime, cacao and other trees, the grubs feeding on 

 the roots and causing the death of the trees. 



During the present year, a severe attack of root borer 

 in canes on one estate in St. Kitts has been accompanied 

 by a remarkable abundance of the weevil Exophtkalmus 

 esuriens, some 40,000 of these insects having been collected 

 on cotton plants in fields adjoining those in which the 

 sugar-cane was so severely attacked by root borer. The 

 grubs had completed their growth and development at the 

 expense of the canes, and the adults, on emerging, had 

 congregated on the cotton plants for the purpose of feeding 

 and mating. 



About the same time, these weevils made their appear- 

 ance in great numbers at the liotanic Station in Montserrat, 

 where they were feeding on the leaves of limes and other 

 citrus plants. During the present month (June), a similar 

 occurrence has been reported from Antigua where 47 acres 

 of limes have been attacked, 7 acres badly, the remainder 

 somewhat, by these weevils. At this place, li3,400 weevils 

 were collected in four days. 



