204 On the Insects affecting the Turnip Croj). 



long manure harbours the beetle^ and if turnips be sown on a 

 stubble-crop, they are often completely destroyed. I see Mr. 

 Webb Hall states that he has had to sow stubble- crops three 

 times over, and seed sown on stubble late in August has been 

 taken off by the beetle in more than one instance. Whether this 

 arises from the hollow straws affording a retreat for the beetles, or 

 that the weeds had supported them or the maggots, so that the 

 chrysalides were lying undisturbed in the land, is not easily ex- 

 plained. 



Mr, Linton and many others recommend drilling-in, not less 

 than three or even four pounds of seed to the acre, and six or seven 

 pounds broadcast ; for he very justly observes, that thick sowing 

 causes the plants to grow much more rapidly when young than 

 thin sowing ; and by drilling in with the seed a peculiar compost, 

 containing the strongest animal manures, the fly, he says, has never 

 yet disappointed him of obtaining a good crop.'^ I think it pro- 

 bable that the ammonia in this potent manure may be disagree- 

 able, if not destructive, to the insect, and the rapid growth of the 

 plant, from its stimulating effects, defies their attacks. The vege- 

 tation of the seed may be accelerated by steeping it in water for 

 twenty-four hours ; and the surest way to obtain a strong crop is 

 to sow seed of the same age, otherwise the plants do not come up 

 simultaneously, and the fly will attack and destroy the crop in 

 detail. 



Mr. Linton also adds that he has found more benefit from the 

 manure he describes in the succeeding crops of clover-seeds than 

 from three or four chaldrons of lime to the acre. With regard to 

 the use of lime, a great deal must depend upon the soil on which 

 it is used, which may account for the conflicting opinions respect- 

 ing its effects in protecting the turnips against the fly. From six 

 to eight bushels of quicklime per acre may be sown over the 

 young plants successfully in dry weather ; but it must be repeated 

 after rain or dew ; and this, as well as soot, requires to be regu- 

 larly and evenly dusted over the plants. Mr. Birk says that he 

 used slaked lime with perfect success ; and although profusely, 

 it did not at all injure the plants. It should be slaked at the 

 time of use, and ought to be spread in the very hot state^ when it 

 burns the fly. Some danger to the plant seems to attend this 

 process, arising from the heat generated by the lime ; at least so 

 I presume ; but some little explanation is required in these state- 

 ments to distinguish clearly between slaked and quick or un- 

 slaked lime. Very different were the results from Mr. Le Keux's 

 experiments. Forty bushels of lime per acre were spread, he 

 says, immediately before the seeds were sown, and did no good ; 



* Journal of Royal Agr. Sec, vol. i. p. 452. 



