394 



THE AGRICULTURAL NEWS. 



1 >E( UMBER 4, 1915. 



INSECT NOTES. 



THE ROOT BORER OF SUGAR-CANE 



AND ITS EFFECT ON MANURIAL 



EXPERIMENTS. 



The reporl issued by the Barbados Department of 

 Agriculture on the sugar-cane experiments for the 



en 1913 1915 has recently been issued. Parts I and 

 II of this repi it deal with Manurial Experiments with sugar 

 cane in Barbados 1913 L915. 



These repi rts do not ordina'nly touch upon the investi 

 gations of the depredations of insect pests, but the root 

 borei has exercised such a mark®! influence on the results 

 of the experiments that a short account of its work is 

 recorded A similar brief statement was presented in the 

 last previous report of the series, viz. that for 1912-1 I. 



The root borer (Diaprepes abbreviatus) has for several 



years been recognized as a serious pest of sugar-cane in 



certain localities in Barbados, but it is only recently that 



been found on the lands where the manurial experi- 



of the I ical Department arc being carried out in 



sufficient numbers for it to be considered a pest of inipor- 



I'.ir the past three years,' the period covered by the 



ipqrts, the depredations of this insert have had 



a serious effect on the results of the experiments. 



The paragraph reproduced below from the report 

 mentioned above indicates the manner in which the canes 

 were injured, and shows the remedies adopted to reduce the 

 numbers of the insect in the infested fields. 



As will be seen, the control measures include the digging 

 out of the stumps and killing the grubs. The other 

 important mi i n which are strongly recommended for the 

 control of this pest are the collection of the eggs, the 

 collection of the adults when they appear and a system of 

 crop rotation. This last course -is not available for these 

 fields since these manurial experiments are carried nut, on 

 the basis of tie anuria! treatment being applied on 



the same plot, with the same crop, season after season. 



The manurial experiment plot is stated to be approxi 

 mately I \ aires in extent and it will be seen from the figures 

 "iven below of the number of grubs collected that the attack 

 was one of considerable intensity, and they indicate the 

 serious effect of this insect on the yield oi canes on the 

 general cultivations oi the sugar-cane estates in the island, 

 where the root borer occurs in large numbers, it being 

 stated that the grub of the root borer 'attacked the canes in 

 the manurial plots this season to snch an extent as to render 

 it impossible to draw any definite conclusions from them.' 



The root borer has been known as a pest oi -nun cane 

 in Barbado aud recently it has been more 



and more in evidence in different sections of the island, until 

 at present it occurs in almost all districts. 



Instances are not wanting of an almost complete control 

 being obtained by collecting the eggs, collecting the adults, 

 digging .-tump-, as soon as the crop i- off, and, this is very 

 important, the rotation oi crops. 



The same problem, perhaps in a less degree in intensity, 



at present confronts sugar-cane mowers in St. Kitts and 



Antigua, the pest being the closely related Exophthalmos 



IK, which, SO far as known, lias the same habit I 



life history as Diaprepes abbreviat us, and sugar cane planters 



throughout the West Indies should enter into an organized 



ind cot ampaign against the attacks of these h 



The foil,, wing paragraph is quoti d 



"The results are given in Tables II to V. As will be 

 sen therefrom the ■■■suits from mosl of the plots are BO 



different from th i previous years, with tin- exception of 



lastyear, and so conflicting with those of some of the other 

 plots as to leave no doubt but that this year a verj disturbing 

 factor has again been pn d which has masked the 



tine results of the manuring. This disturbing factor « is, as 

 in the previ . the grub of the root borer (Diaprepes 



abbreviatus, Linn.), which has attacked the canes in the 

 manurial plots this season to such an extent as to render it 



impossible to draw any deliuiti nclusions from them. Even 



before the canes were fully matured some were seen to be 

 drying, and on two occasions clumps ..mounting altogether to 

 forty-nine and to be reaped or they would have dried up and 

 been lost. From the basal portions of these clumps 1,022 

 larvae of the root borer were obtained. As soon ;«s the 

 remainder of the canes were mature thej "ere reaped in the 

 usual manner, and as 'quickly as psssible after this tin | 



portions of cadi clump were dug up, cut into pieces, and the 

 larvae extracted and killed. At the same time the old cane 

 holes were dug out two feet square and ten inches deep, and 

 all the larvae found in the soil killed. In no instance was the 

 basal portion of any clump ol canes of the manurial plots 

 tree from the pest, and it may be here si kted that, including 

 those mentioned above, 8,059 larvae were killed, orovei in 

 average of five larvae to the clump. The digging out of the 

 basal portions of the clumps, and enlarging tin- old cane 

 hole- to search tor and kill the pest is a somewhat expensive 

 method of dealing with the attack, but owing to the 

 importance of freeing the manurial plots as far as possible 

 from this pest, it was necessary to take 'he measure most 

 likely to be , Effectual.' 



H.A.B. 



According to information received at the office of 

 II. M. Trade Commissioner in South Africa, from the Com 

 missioner of Customs and Excise at Pretoria, interesting 



experiments wit] tton mowing are about to be uudei 



in Natal, with a view ti ascertaining the more suitable variety 



for cultivation then-. The planting and cultivation are to be 



supervised by the Government Officer in charge of tol 



and cotton investigations in the Province. The Government 

 has erected a ginning plant at Durban, where 3eed-cotton 

 from farmers in all parts of Natal and Xululand will be 

 ginned and baled ready for the market at a cost of Id. per ft). 



on the lint. (The Board qt Trade Journal, October 14, 1915.) 



According to the Dominica Chronicle for November I 1 ', 

 ill -.ports ot lime products from Dominica up to October 31 

 v..i as follows: raw lime juice, 598,565 gallons; conceit 



lime juice, 89*293 gallons; ami lime juice cordial, 1,500 



gallons. Tin 1 figures lor tie corresponding period of 1914 

 were 304,503, II 1,497 and 3,622, respectively. During the 



same period, 717 cut. of citrate of lime was exported as 



against 1,540 cwt. in 1914. The exports of Hi il, both 



ecuelled and distilled, declined also, and there is also 



a general reduction in the exports of fruit such as coco nuts. 



linn s, bananas and oranges. 



