OABBOT FLY. 13 



in case the ground might be foul, but always with the same result, 

 failure."— (J. S.) 



So far as I can tell, it appears that unless care is taken in 

 cultivation, and in the various common-sense measures which suggest 

 themselves to all (such as not sowing on previously infested ground), 

 infestation is much more likely than not to appear ; and that even ivith 

 every precaution, if proper measures are not used at thinning time, the 

 crop may be ruined by the " Rust " maggot. 



We have notes of failure on good land, on fresh land where the 

 ground could not have been previously infested, and also where care 

 had been taken in preparation and manuring of the ground. 



Bruising the young plants by careless treatment (as by treading 

 among them) will also bring attack, as I found in my own garden in 

 1890. Large clumps of Scarlet-runner Beans happened to be placed 

 at distances along one side of a long border of Carrots. The man em- 

 ployed to stake the Beans carelessly trampled the Carrots close by, and 

 shortly the discoloured leafage showed the mischief had begun in front 

 of the Bean clumps, which gradually spread on each side of the injured 

 spots, so that the border was very obviously alternated by the cross 

 stripes of good and bad Carrots. 



The fact of attack following exactly on thinning operations was well 

 shown in a note sent from near Dingwall, N.B., where, in 1880, it was 

 observed that on beginning thinning, the grub began too, " and within 

 three weeks spoiled them for use." .... "Late ones alongside 

 escaped until we began to use them ; but by keeping to the side the grub 

 was on, it kept up to, but did not advance beyond, the damaged part." 



How far the Rust Fly may be attracted by the smell of the bruised 

 Carrots cannot surely be known with certainty ; but it is strongly 

 advised to remove all dead and dying plants, and broken pieces of root 

 or leaves, after thinning. Copious watering after thinning (unless 

 weather is such as to make it undesirable) acts well, both by closing 

 the disturbed soil and preventing the growth of the disturbed plants 

 being checked. 



In garden cultivation this may often be done simply by the use of a 

 garden watering-can. Where there is water supply and a hose, I have 

 found sending a single jet of water from it very hard, in a straight line 

 between or beside the rows, to answer well for slight earthing up. The 

 force of the water tears a shallow furrow, and sends the earth flying on 

 both sides of it on to the plants to be protected, and also gets rid of 

 insect vermin that may be about. Any application, mixed with the 

 water, which is beneficial to plant growth and objectionable to insects, 

 is of course desirable. 



For refreshment of the plants themselves, where there may be a 

 larger extent of Carrot beds to be attended to, the use of the Eclair 



