l84 TUENIPS. 



supply of manure, depreciation of price of stock, &c. ; so that 

 it is almost impossible to say bow far the loss extends. 



Tbe names of counties infested, and otber details by Avbicli 

 to work out the calculations, are given in my Eeport above re- 

 ferred to, but I give the abstract now as an example of how, 

 under circumstances favourable to its development, one of our 

 commonest crop infestations may, by its unproductive outlay, 

 and the losses following in its train, become in the fullest 

 sense a national calamity. 



Prevention and Eemedies. — Some of the points that need 

 particular attention are 1st, clearing off such weeds as the fly 

 feeds on till the Turnips are ready for it ; 2nd, such a method 

 of cultivation and manuring as shall give a fine, deep, clean, 

 and moist seed-bed, rich in available plant-food, so that a 

 healthy and rapid growth may be promoted, and all points of 

 shelter or harbourage for the " Fly " be reduced to the lowest 

 limit ; and 3rd, applications and special treatment to destroy 

 the fly when it is badly infesting a crop. 



With regard to weeds : — The fly frequents wild plants of the 

 Cabbage tribe, as Shepherd's Purse, Jack-by-the-Hedge, and 

 is especially fond of Charlock. It has been observed as 

 unusually numerous where this weed has been plentiful in the 

 previous year, and also to spread (as from a centre) to the 

 neighbouring crops from a Charlock-infested field. It is often 

 supported in the spring by these or other weeds till the 

 Turnips are large enough for it to attack, and therefore means 

 should be taken to get rid of them beforehand from the 

 autumn stubbles. In the case of Charlock a double turn of 

 the harrow over the stubble is of use ; small weeds may be 

 cleared by broad-sharing; the seeds are thus covered suffi- 

 ciently to induce immediate germination, and the sprouting 

 weeds as well as roots in the soil will be cleaned by the 

 regular processes of cultivation further on. Waste spots of 

 land and hedge-sides should also be attended to ; the first is 

 often overrun with Shepherd's Purse ; the second is often in- 

 fested with the tall, large-leaved, onion-like smelling plant 

 with white flowers the shape of the Charlock-blossom, known 

 as " Jack-by-the-Hedge." 



Tlie methods of cultivation recorded as successful in ordinary 

 years, or in helping to bring a fair amount at least of the 

 plants through attack in bad seasons, will be found to be 

 based on knowledge of the ^vants of the Turnip-plant and the 

 hahits of the Turnip Fly. 



The Turnip is very succulent, and needs plenty of food and 

 moisture, and moderate warmth to press on growth ; and the 

 attacks of the Turnip Fly are most serious in heat and drought, 



