188 



THE AGRICULTURAL NEWS. 



April 23, 190-t. 



INSECT NOTES. 



The Fumigation of Imported Plants. 



The necessity for adopting jd-eventive measures against 

 the introduction of insect i)ests lias ah-eady Ijeen dealt with 

 in the Agricultural Neu's (Vol. Ill, p. 74). In that article 

 it was mentioned that Jamaica had for .some time been 

 enforcing the fumigation of imported plants and that British 

 Guiana had recently enacted a law for the same purpose. 



Of the Lesser Antilles, Dominica is the first to make 

 a positive start in this matter. Fumigating chambers have 

 lieen built and materials for fumigating have been procured. 

 The fumigating chambers are of two sizes — one, 8 feet by 6 

 feet by 6 feet inside, and the other 2 feet by 2 feet by 2], 

 feet. They are built of matched i!-inch pine (deal) boards, 

 double boarded with a sheet of building paper between, and 

 made as nearly air-tight as possible. 



The fumigation is accomiilished by means of hydrocyanic 

 acid gas. This is produced by the addition of potassium 

 cyanide to a mixture of sul[ihuric acid and water. The 

 cyanide should be 'miner's fused', of a strength of 98 to 99 

 per cent., and the sulphuric acid, a good grade of commercial 

 acid, with a specific gravity of not less than 1 ■8.'3. 



For use in a box or chamber I oz. of cyanide should be 

 used for each .'500 feet (cubic content), and for generating 

 the gas a vessel of wood, glass or earthenware, but never 

 metal. The amount of acid should be one and a half times 

 the amount of cyanide and tliat of water one and a half times 

 as nmch as of acid. The amounts for the large fumigating 

 chamber mentioned above would then be : cyanide, 1 oz.; acid, 

 li oz. ; water, '2\ oz. ; and for the smaller box, cyanide, 1 

 gramme ; acid, \\ cc. ; water, 2^ cc. 



An arrangement should be made so that after the 

 mixture of acid and water is placed in the generating vessel, 

 the cyanide, loosely wrapped in soft paper, can be added, 

 after all door.s, etc , are closed. This is accomplished liy 

 means of a string through a hole in the side of the chamber. 

 The plants or fruits are put in place, the water and acid in 

 the generator and the charge of cyanide suspended aliove the 

 generator by the string. 'When all is .seouely closed, the 

 cyanide islowcred intothe generator, and the smallhole through 

 which the string passes closed by means of a cork or wooden 

 plug. When the cyanide is dropped into the acid and water, a 

 violent bubbling takes place and a cloud of steam is given 

 off ; this steam is mixed with the jioisonous hydrocyanic gas, 

 which contimies to be given off till the cyanide is used uji. 



As hydrocyanic gas is extremely jioisonous, the greatest 

 care is necessary on the part of the oiierators not to breathe 

 it. It is nearly colourless, with a strong odour of burnt 

 almonds, which is easily detected by one familiar with it, 

 even when jiresent in small quantity. 



For ordinary jilants, the time recjuired in funngating is 

 one hour, but more tender jilants may be exposed for a 

 shorter time, or the amount of the material used may be 

 decreased. At the end of the required time, the doors and 

 ventilators should be opened and the fumigating chamber 

 allowed to become free from the gas. Not less than fifteen 

 minutes should be allowed to pass before anj-one should enter 

 or breathe the air at the door or window. 



The Mealie Grub. 



The Transvaal A;/rirulfural Jottrual for .January 190-t 

 contains an interesting article on the Mealie Grub (Sesamia 

 fusra). The insect is one of the Noctuid moths and its 

 hal>it of feeding in the mealie (maize) plant is very similar to 

 the habit «i the Moth-borer of the Sugar-cane {Dlatrcea 

 sarcharalis) of the West Indies. 



The eggs are laid on the leaf and the young caterijillar 

 works its way down into the heart and stem of the plant, 

 seriously injuring or killing the plant. 



The remedies suggested are — (1) Taking out the affected 

 plants and destroying them ; (2) rotation of crops ; (.3) late 

 planting ; and (4) fall i.loughing or burning of stalks. 



It may be of interest to note that the Mealie (irub of the 

 Transvaal is the Sugar-cane borer of Mauritius, while the 

 Moth-borer of the sugar-cane in the West Indies is known in 

 the I'nited States and other places as the Larger Corn-stalk 

 borer. 



LEEWARD ISLAXDS: REPORT ON SUdAR- 

 CAXE EXPERIMENTS, lUO^-S. Part II. I!y Franci.s^ 

 Watts, r..Sc., F.I.C., F.C.S., Government Analytical and 

 Agricultural Chemist. Price !«. 



This part of the report deals with the experiments that 

 have been carried out during the year in the Leeward Islands 

 to ascertain the manurial reijuirements of the .sugar-cane. 



It is proved that the use of artificial manures is not 

 renumerative with plant canes, the use of jien manure and 

 the jiroper preparation of the land being all that is necessary 

 to give maximum crops : with ratoons, on the other hand, 

 artificial manures are decidedly remunerative. For these 

 nitrogen, in a raj>idly acting form, must be used. Th& 

 experiments also bring out the desirability of applying the 

 nitrogen in one dose rather than in divided doses. 



An ai)pendix to this report deals with the relationship 

 between the tonnage of cane and the pounds of sucrose in 

 the juice — a question of great importance in connexion with 

 experiments of this nature. Mr. Watts states : 'It is probable 

 that we shall in the future make our comparisons in 

 mamu'ial experiments on the basis of tons of canes, rather 

 than of pounds of sucrose.' 



LECTURES OX AGRICULTURAL SCIEXCE: By 



Longfiekl Smith, B.Sc. (Edin.), Ph.D. (Leipzig), Lecturer 

 in Agricultural Science at Barbados. Price 3(/. 



This is a summary of the lectures that were delivered 

 by Dr. Longfield Smith at Barbados in 1902 and 1903 and 

 in Bermuda in 1904. In these lectures a wide range is 

 covered, as elementary facts in chemistry, physics and biology, 

 directly or indirectly connected with agriculture, are discussed. 



This publication is likely to be of considerable use to 

 officers of the Department and others in connexion •svith 

 lectures to teachers. 



