THE TURNIP FLY.

Waikato Times, Volume XVII, Issue 1437, 17 September 1881, Page 4

THE TURNIP FLY.

The " turnip fly " has ever been ono of our most destructive pests, and its ravages is fit present general over all Scotland. The uudernoted has been written in the hope that it may prove of some service 'in averting this evil in future, and be th 6 means of in some light degree mitigating th^ injury our crops are at present bitstaining. The volume from which theso notes have been taken (at present in the press, and its issue may be shortly expected) is entitled, A M«iuml of Injurious Insects, ami Jfitlioih of I'levoitioii, by E. A. Ormeiod, F.M S., Ibleworth, a^ laborious and painstaking worker in the field o f entomology, who has during the last four years been in communication with over 400 observers in all parts of the country, who report to her all insect attacks upon our food crops, forest trees, and fruit ; and the modes of prevention or remedies that have been adopted to meet the evil. Theso remedies are therefore such as have undergone the test of practical experiment, and have been compiled from notes forwarded by trustworthy observers. With these preliminary remarks I now place before your readers a few extracts from the proofs of the book, which I have had the privilege of perusing :—: — " During winter tho turnip fly beetles may be found sheltered under bark, fallen leaves, clods of earth, and the like places ; also amongst stubble, and especially in heaps of long strawy manure left on the fields ; and onjpnrticularly fino Jays ihey may be seen coming out to sun themselves. " On the return of spring warmth they begin woilc, and, till the crops tire ready for them. .11 c (Specially to be found on woods of tho h.imo family as tho turnip and cabbage, such as charlock, hhopheul's pursg, and .(..ck-by-thc-hcd-rc. " When tho attack begins on the turnip tho female lays her egg 1 -, which aie few in number, for successive days on the under side of the rough leaf. The maggots which hatch from these in ten days are white or yellowish, fleshy, and cylindrical, with three pairs of feet in fiont, and a sucker-foot at the end of the tail. Tho head is furnished with cutting jaws, arid has laige dark eyes. Diiectly they] are hatched thoy gnaw through the lower fikin into tho pulp of the leaf, and make their way onwatds, forming winding buriows inside it. Hero they feed foi about hiv d.iyh, then they come out and bury themselves not quite 2 inches deep in the ground, when they turn into thp chrysalis stage, from which the ' turnip fly ' or ' flea beetle' comes up in about fourteen days. "It is in this .state that the so-called ' fly ' does most mischief. It gn.iwn the seed leaves, and the young plant when it fust springs, and thus often totally destroys it ; and also gnaws the rough leaves, forming largo holos through the leaf "There may be five or fix bioods in a Beason — (' Farm Insects ') •' I'm ml 'Km a i'il llnm d 'if. —The points that need particular attention aie— lst, dcai ing off sii'jii weeds as tho fly feeds on till the turnips aie leady for it , 2nd, such a method of <-ulti\atiou and manuung as shall give .1 fine, deep, clean, and moist seed-bed, nch in .lv.uhble plant food, so that a healthy and lapid growth may be promoted. ,md all point*, of shelter or harbourage for the fly bo reduced to the lowest limit ; 3rd, available means of applying moisture in diy seasons ; 4th, applications and special treatment to destroy the fly when it is !>oldly infesting- a ciop. '' With regard to weeds :— The fly frequents wild plants of the cabbage tiibe, as shepherd's pnrso, J.ick-bv-the-hcdge, and is especially fond of chailock. It has been observed a-* unusually numcious where this has been plentiful in the previous ycai, and also to spiead (as from it contie) to the neighbouring emps fiom a chii lock-infested field It is often suppoitcd in the spiing by these or other weeds till the hi. mips aio largo enough for it to attack, and theiefoic means should bo taken to get rid of them beforehand from tho autumn stubbles In the case of chailock a double turn of the haiaow over the stubble is of use. small weedi miv be cleared by broad-sharing , the seed-, aie thus coveted sufhcicnUy to induce immediate goimiuation, and the spi outing weeds, ,is well as roots in the .soil, will be cleaned bv tlie legular processes of cnltnation fuithcr on. Waste ppots of land <md hedge-sides shoald also be attended to ; the lust is often ovenun with shepheid's pmi-c; the second is often infested with the tall, l.n ge-baved, onion-like smelling pLmt with w hite iloweis. the shape of the c liarlock blossom, known as 'Jack-by-tho- hedge.' "A deep culthaUon that will turn down A\eeds and deshoy inserts is very serviceable, ,md care' should be taken that ail inanuie fiom the yazd-> or sheds should be completely buiied. Any long strawy lumps left on the mi 1 face will shelter tho fly, and fiom these it will come out to tho distinction of the crop. "The thiee requisites for healthy gernnnition aie waimth, moisture, and some amount af air , and it is (mlv by .seeming these thai a rapid and healthy development of Iho plant can be obtained It has Iheiefoie been recommrnded, when tho hintace is piepaied foi dulling, to leave it undisturbed for thuo weeks ; also, on the other hand, when partly lotted farm manure is ploughed in 111 spiing, to sow immediately. In each case the reason is the same' — that is, to .secure the moisture in the ground— in one instance by not opening the pulverised e.uth more than can be helped, and in the other way by putting the seed above the halt-rotted dung, befoio the moistuie and warmth accompanying decomposition has gone from it. 11 Thick sowing is advised by various growers, ■who state that thus, in case of hot dry weather, the plants will thrive better for the protection they give to each other (being tbu« moderatply damp, with the roots shaded), and that some may be reckoned on to escape tho fly. This, however, needs careful looking to, or the lesult will only bo a worthless drawn growth. " With regard to swedes, it lias been found, fiom the preference of the fly for the white turnip, that if the seed is mixed in the proportion ol one-quarter white to three-quarters suede, or again, if one diill of white is put in at intoivals umongst the swedes, that the fly will be attracted to the white, and thus allow , the swedes to get well ahead, This plan was found to answer well by several ■ years' experience in East Lothian and , elsewhere. ! "The turnip fly is'active in blight dry , weather; and when the thermometer ; stands at 7odeg-. in the shade it has been observed on the wing in great numbers ; when the weather, on the contrary is . cold and wet, it is sluggish ; and in rain . or heavy dew these beetles cannot leap, \ from the moisture clogging < their legs, and thus preventing the powerful springs with which they customarily leap out Of the way of attack. i "This circumstance has much to do i With the very different circumstances^ of exactly the same remedy. A dressing that is put on early in the morning-, 1 ■whilst the dew is still heavy on the plant fi has a very different effect tojwhat it has s either on a morning that ia dew-lens or in the middle of the day, when the fly has I every chance to protect itself under clods a of earth, &c.,, before the dressing reaches t it ; and, though the- reason, ia not given, 3

the advice is conßtaijtl^ £he/same in observations on remedies— apply whilst the dew. is on. ''With regard 'to 1 the dressing when the fly is prescht-<-sprifc, lime, rond diißt, and others of the u«unl applications have been found useful, and may all bo serviceable if applied when the dew is on ; but the remedy that' appears 'the best | nvoved is the one noted by Mr Fisher Hobbs as having never failed during the eight years in which he made use of it. I give the recipe and pas Sago at length from his statement madd before the Council of the Royal Agricultural Society, quoted in fcho Of/nteiia's' Ohronirh', and Aqneullard Gazette^ for May 28, 1559, p. 173 :- " Ono bushel offwhite gas-ashea' (gaslime) ' fresh from the gas-house, i buj-h. I of fresh lime from the kiln, 61b of sulphur, and 10 lb. of soot, well mixed together and got to as fine a powder as possible, so that it may adhere to the young 1 plant. The above is sufficient, for 2 acies, when drilled at 27 inches. It should be applied very early in the morning when the dew is on the leaf, a broadcast machine being the most expeditious mode of distributing it ; or it may be sprinkled with tho hand, carefully over the rows. If the fly' continues troublesome, tho process should be repeated ; by this means 200 to 220 acres of turnips, bwedes, and rape, have been grown on my farm annually for eight or nine years without a rod of ground losing plants. Tho above is a strong dressing, to be used when the fly is very numerous and has never failed when applied at night. Numerous experiments have been tiied, and amongst them I recommend the following in ordinary cases. • • • Fourteen pounds of sulphur, one bushel of fie«h lime, and two bushels of roadscT.ipins:3 per acre, mixed together a few ilriy.s before it h used, and applied at night, either by means of a small drill of strewed along the rows by hand. I have known sulphur mixed with water applied vi a liquid hUto by means of watcrenrts during the night, and tho horse-hoe immediately following the watercatt. This h.vs succeeded admirably" — George Biown in the Agt icuUiaal Gozvltc,