524 



THE TROPICAL AGRICULTURIST. 



[Janttary I, 1884. 



be brought to a fine tilth. It is not absolutely 

 necessary that the soil be turned up to any great 

 depth, practically, four inches is enough, but it is 

 absolutely neoeesary for full crops, and good healthy 

 plants, that the subsoil be loosened and stirred, and 

 that as dei-'p as ever it can be done. An iron plough 

 followed by a nugra country plough would do this. 

 " Shortly before sowing, the surfaci soil should be 

 brought into as fine a tilth as is possible, to receive 

 the seed. When the requisite degree of fineness has 

 been obtained, the surface should be rolled down in 

 order to render it sufficiently compact and even, to 

 prevent tlie seed, which shoxild always be sown in 

 lines to admit of after cultivation, from being buried 

 too deeply; in fact, probahly half an inch deep ia 

 amply sufficient for so small a seed, and were it not 

 that the sun is, whenever it appears, so powerful, 

 scorching, and destructive to young plants, it might 

 be sown with advantage on the surface and only 

 covered, as clover is, with a brush harrow." 



No h.ird and fast rule though should be adopted 

 as to tlie proper depth to sow the indigo seed. It 

 should depend on the nature of the soil ; a quarter 

 of an inch deep in some soibs, would be equal to an 

 inch in others ; as a rule, the indigo seed is sown 

 much too deep. In sowing indigo, as well as other 

 small seeds, it should never be forgotten that the 

 nearer the seed is to the surface, aud kent moist 

 enough to germinate, the stronger as a rule' wdl the 

 plants be. "To know just the depth the ground will 

 be moist enough to sprout the seed requires more 

 than an ordinary amount of intt-lligence. On light 

 sandy loam it is safe to plant much deeper than if 

 the land be low, and moist, aud heavy. The smaller 

 the setd the nearer the surface " should be the rule. 

 Indigo seed planted too deep exhausts a large portion 

 of its vitality, aud will not make that vigoious growth 

 it would if planted at the right depth, or even on 

 the surface. No rigid rule shuuld be made, the cou- 

 dilion, texture, and nature of the soil, and the state of the 

 weather, should be taken into consideration, and 

 the seed be sown just deep enough to germinate ; just 

 deep enough to keep the aeed sufficiently moist to 

 germinate. W. 



INSECTICIDES. 



Notwithst.andiug the immense variety of substances 

 known to be destructive of animal life, aud the large 

 number of preparations offered as insecticides, the 

 gardener, the orchardist and the fanner remain very 

 much at the mercy of their numerous insect foes ; they 

 have the means of killing them, but the difficulty lies 

 in the application of those means ; the materials for 

 the warlare ure sufficiently abundant, but the foe will 

 not '* come and be killed/' he lives and increases in 

 all sorts of out of the way places, and frequently a 

 large amount of time and ingenuity have 10 be ex- 

 pended before an opportunity is found of comiug to 

 close quarters ; even when the insects are visible in 

 thousands on plants or trees, it is an almost endless 

 task to get rid of them. The only principle of 

 action that ia efficient and economical of time aud the 

 munitions of war is to take them early, if possible, in 

 the first stages of their existence, or, if that ia unat- 

 tainable, then before they have had time to breed 

 and thus increase their numbers. 



Insecticides are found in both the mineral and the 

 vegetable kingdoms, the latter being much the more 

 numerous. Among the former, arsenic is a deadly 

 poison to all insects to which it can be applied ; it is 

 .generally used as a preparation known a» Paris green, 

 which 13 infused or partly dissolved in water and 

 applied with a sjringe or watering pot. It is much 

 used in the United States on potatoes infested with 

 the bug, for which it is a perfect remedy. In that 



case, being applied only to the tops of the potatoes, 

 its use is not at all dangerous ; but there are many 

 cases to which, on that account, it could not be applied. 

 It has been recommended as a preventive of or remedy 

 for the Codlin Moth, though we have not seen a 

 statement of how the efi'ect is produced. The re- 

 commendation is that it should be syringed over the 

 trees when in blossom, but whether that prevents the 

 parent moth from laying her eggs in tlie blossoms, 

 or poisors the wovmo after they are hatched, does 

 not appear. At any rate, it would be well if some 

 of our orchardists would try it by way of experiment, 

 and probaldy they may deem it prudent to dress 

 some of their least valuable trees, though we do not 

 anticipate that any harm would ensue from an outward 

 application, while the quantity would be too small to 

 have any effect tipon the roots; neither is there likely 

 to be any danger of the poison remaining on the 

 fruit till it is fit for use, as the quantity that falls 

 on the incipient fruit would bs infiuitesim.al. Sulphur 

 is another mineral that exercises a ileleterious influence 

 upon certain insect?^, though not in its crude state, 

 in which it has no more powirtban as much sand; 

 but a slight det^ree of heat suffices to cause decnmpsilion, 

 when sulphurous acid is produced, and that is a deadly 

 poison to both animal and vegetable life, therefore re- 

 quiring to bfl used with caution ; fortun^ately a pro- 

 portion in the air that is destructive to red spider 

 aud the lower vegetable parasites — fungi — has no per- . 

 ceptible eft'ect upon plants, though a slightly larger 

 amount would prove very injurious, as many in- 

 experienced persons have found, when, in their anxiety 

 to produce a .sufficient amount of the gas, they have 

 placed the sulphur on hot smoke flues in iheir vineries 

 or other houses, to the destruction of both plants and 

 insects. In the open air and merely under the in- 

 fluence of the sun the amount of gas generated, though 

 sufficient for the desired purpose, producis no ill eflect 

 on the vines or others plants to which it may be 

 applied. Petroleum, either crude or in the refined 

 from of kerosene, is qiiiclily aud entirely fatal to in- 

 sect life, and is jf such a nature that it searches into 

 every crevice where au insect can penvtrate, and also 

 takes instant effect upon the mealy bug and others 

 that are covered with a downy substance impenetrable 

 to many other liquids. Though this substance pro- 

 duces little or no ill elTeot upon the bark or other 

 hard parts of plants it is destructive of nearly all 

 young or tender parts, and therefore requires to be 

 used with great cintion and to be washed off im- 

 mediately, which, fortunately, can be done without 

 its efficacy being at all impaired, for a touch of it ia 

 death to any insect of whatever kind. It is difficult 

 to apply with moderation, as it will not combine with 

 water, but an emulsion, soluble in water, may be 

 made with soft soap or milk. Professor Riley, the 

 celebrated American entomologist, gives the following 

 recipe for its preparation : — Ketined kerosene, two 

 parts ; sour milk, one part ; or, if milk cannot be ob- 

 tained, then condensed milk is employed, as in the 

 following formula : — Kerosene, one gill ; condensed 

 miik, a pint iind a half; water, three pints. First 

 mix the milk and water, then add the oil, and churn 

 till a sort of butter is produced. When required for 

 use this is diluted witn twelve to sixteen times its 

 bulk of water, so that the emulsion resembles milk, 

 and it may in this state be employed with safety. 

 Ammoniacal gas is also thoroughly destructive of in- 

 sect life, aud may be at tbe same time beneficial aa 

 a manure, Ammoniacal liquor from gasworks forms a 

 powerlul insecticide. 



Of all vegetable substances, tobacco ia one of the 

 most potent, whether used in powder or hs smoke ; 

 still there are some insects, such as mealy bug, upon 

 which it produces little or no eft'eot. Pyrethrum pow- 

 der has recently obtained a great name as an insecticide 



