630 



FARMERS' REGISTER, 



[No. n 



this principle is at once a nourishment of plants 

 and animals, and the greatest ravages are com- 

 mitted upon crops in this first stage of their 

 growth. 



The turnip fly, an insect of the colyoplera ge- 

 nus, fixes itself upon the seed-leaves of the turnip 

 at the time that they are beginning to perform 

 their functions; and when the rough leaves of the 

 plume are thrown forth, it is incapable of injuring 

 the plant to any extent. 



Several methods have been proposed for de- 

 stroying the turnip fly. or for preventinnc it from in- 

 juring the crop. It has been proposed to sow 

 radish-seed with the turnip seed, on the idea that 

 the insect is fonder of the seed-leaves of the ra- 

 dish than those of the turnip: it is said that this 

 plan has not been successful, and that the fly feeds 

 indiscriminately on both. 



There are several chemical menstrua which 

 render the process of germination much more 

 rapid, when the seeds have been steeped in them. 

 As in these cases the seed-leaves are quickly pro- 

 duced, and more speedily perform their functions, 

 I proposed it as a subject of experiment to ex- 

 amine whether such menstrua miffht not be use- 

 ful in raising the turnip more speedily to that state 

 in which it would be secure from the fly; but the 

 result proved that the practice was inadmissible; 

 for seeds so treated, though they germina'ed 

 much quicker, did not produce healthy plants, and 

 often died soon alter sprouting. 



I steeped radish-seeds in September, 1807, for 

 12 hours, in a solution of chlorine, and similar 

 seeds in very diluted nitric acid, in very diluted 

 sulphuric acid, in weak solution of oxysulphate of 

 iron, and some in common water. The seeds in 

 solutions of chlorine and oxysulphate of iron threw 

 out the germ in two days, those in nitric acid in 

 three days, in sulphuric acid in five, and those in 

 water in seven days. But in the cases of prema- 

 ture germination, though the plume was very vi- 

 gorous for a sliort time, yet it became at the end 

 of a fortnight weak and s'ickly; and at that period 

 less vigorous in its growth than the sprouts which 

 had been naturally developed, so that there can 

 be scarcely any useful application of these experi- 

 ments. Too rapid growth and premature decay 

 seem invariably connected in organized structures; 

 and it is only by following the slow operations of 

 natural causes, that we are capable of making im- 

 provements. 



There is a number of chemical substances which 

 are very otTensive and even deadly to insects, 

 which do not injure, and some of which even as- 

 sist vegetation. Several of these mixtures have 

 been tried with various success, a mixture of sul- 

 phur and lime, which is very destructive to slugs, 

 does not prevent the ravages of the fly on the 

 young turnip crop. His Grace the Duke of Bed- 

 ford, at my suggestion, was so good as to order 

 the experiment to be tried on a considerable scale 

 at Woburn farm: the mixture of lime and sulphur 

 was strewed over one part of a field sown with 

 turnips; nothing was applied to the other part, but 

 both were attacked nearly in the same manner by 

 the fly. 



iVlixtures of soot and quick-lime, and urine and 

 quick-lime, will probably be more efficacious. The 

 volatile alkali given off by these mixtures is offen- 

 sive to insectsj and they afford nourishment to the 



plant. Mr. T. A. Knight* informs me, that her 

 has tried the method by ammoniacal fumes with 

 success; but more extensive trials are necessary 

 to establish its general efficacy. It may, however, 

 be safely adopted; for if it should fail in destroy- 

 ing the fly, it will at least be a useful manure to 

 the land. 



After the roots and leaves of the infiant plant 

 are formed, the cells and tubes throughout its 

 structure become filled with fluid, which is usually 

 supplied from the soil, and the function of nourish- 

 ment is performed by the action of its organs upon 

 the external elements. The constituent parts of 

 the air are subservient to this process; but, as if 

 might be expected, they act differently under dif- 

 ferent circumstances. 



When a growing plant, the roots of which are 

 supplied with proper nourishment, is exposed iti 

 the presence of solar light to a given quantity of 

 atmospherical air, containing its due proportion of 

 carbonic acid, the carbonic acid after a certain time 

 is destroj^ed, and a certain quantity of oxygen is 

 found in its place. If new quantities of carbonic 

 acid gas be supplied, the same result occurs; so 

 that carbon is added to plants from the air by the 

 proce.ss of vegetation in sunshine; and oxygen is 

 added to the atmosphere. 



This circumstance is proved by a number of 

 experiments made by Drs. Priestley, Ingenhousz, 

 and Woodhouse, and M. T. de Saussure; many 



* Mr. Knight has been so good as to furnish me 

 with the following note on this subject. 



" The experiment which I tried the year before 

 last, and last year, to preserve turnips from the fly, 

 has not been sufficiently often repeated to enable me 

 to speak with any degree of decision; and last year 

 all my turnips succeeded perfectly well. In conse- 

 quence of your suggestion, when I had the pleasure 

 to meet you some years ago at Holkham, that lime 

 slaked with urine might possibly be found to kill, or 

 drive off, the insects from a turnip crop, I tried that 

 preparation in mixture with three parts of soot, which 

 was put into a small barrel, with gimlet holes round 

 it, to permit a certain quantity of the composition, 

 about four bushels to an acre, to pass out, and to fall 

 into the drills with the turnip seeds. Whether it was 

 by affording highly stimulating food to the plant, or 

 giving some flavor which the flies did not like, I can- 

 not tell; but in the year 1811, the adjoining rows were 

 eaten away, and those to which the composition was 

 applied, as above described, were scarcely at all 

 touched. It is my intention in future to drill my crop 

 in, first, with the composition on the top of the ridge; 

 and then to sow at least a pound of seed, broad-cast, 

 over the whole ground. The expense of this will be 

 very trifling, not more than 2s. per acre; and the horse- 

 hoe will instantly sweep away all the supernumeraries 

 between the rows, should those escape the flies, tO' 

 which, however, they will be chiefly attracted; be- 

 cause it will always be found that those insects prefer 

 turnips growing in poor to those in rich ground. One 

 advantage seems to be the acceleration given to the 

 growth of the plants, by the highly stimulative effects 

 of the food they instantly receive, as soon as their 

 growth commences, and long before their radicals have 

 reached the dung. The directions above given apply 

 only to turnips sowed upon ridges, with the manure 

 immediately under them; and I am quite certain, that 

 in all soils turnips should be thus cultivated. The 

 close vicinity of the manure, and the consequent short 

 time required to carry the food into the feaf, and re- 

 turn the organizable matter to the roots, are, in my 

 hypothesis, points of vast importance; and the results 

 in practice are correspondent." 



