Science and Practice in Farm Cultivation Part 23

1. The _Slug_ may be described as a houseless snail. There are several species, but the milky slug (_Limax agrestis_) and the black slug (_L.

ater_) are those most common to our corn crops, and are more especially mischievous to wheat; for, as this crop usually succeeds clover or "seeds," in which they breed most rapidly, so, the older the clover lea, the more eggs will be ready to hatch in the wheat crop, and this all the more readily as the wheat is nearly always put in with a single ploughing, and with as little cultivation as possible.

The best remedy will be found in encouraging insectivorous birds-the lark, rook, starling, peewit, and others, eating them either in the egg or young state with great avidity; a good a.s.sistance to whose labours may be supplied in a few broods of ducks from the farmyard, which it will pay well to have tended by a good boy-where such can be found-as these birds are most efficient as destroyers of slugs and caterpillars.

Store pigs turned into old leas, where they can do no mischief, will get no bad living where snails and insects abound.

_Wire-worms._-The several species of beetle which produce the wire-worm belong to the genus _Elater_. They are of a long oval shape: about half the length belongs to the head and thorax, and the other to the abdomen.

Every schoolboy knows that when he holds the insect on its back it elevates the abdominal portion, and again lets it fall so as to make a beating sound; and hence its generic name, and also its common name of click-and-hammer beetle. If he remove his finger when in this position, the creature immediately skips up and turns on its feet, from which action it has got the name of "skipjack."

Curtis has estimated nearly seventy species of click-beetles as producing wire-worms in this country; but the three following are those generally met with-_Elater lineatus_, _E. obscurus_, and _E.

ruficaudis_. These all attack corn and almost every other kind of vegetable.

The larvae of these are very much alike, being hard, leathery, wiry caterpillars, which vary in length to about three-quarters of an inch, according to age. These are mostly smooth, and have six feet on their thoracic segments, and a false foot or _proleg_ in the middle of the underpart of the terminal section of the abdomen-characters by which wire-worms may be distinguished from all others. Their length varies with age; as they live for some years in the larva state, so the different sizes mark so many broods, which in some fields are annually provided for. It should here be observed that the wire-worm does not breed; these larvae can only be hatched from the eggs of the female click-beetle: hence, then, destroying the worms prevents the development of their parent.

Now, as we have seen whole fields of wheat destroyed by wire-worms, it becomes important to examine the nature of this attack, with a view to point out a remedy. If, then, we go into a corn field in early spring, and see the young wheat blades looking yellow and sickly, we shall seldom be long in finding the wire-worm, on carefully taking up some of the affected plants. Its position will be at the base of the plant, sometimes eating its way into its centre, and so eating out its very heart; or perhaps it may nibble away the outer coat of the young stem, and so prevent any nutriment pa.s.sing into the blade. One worm will be enough to kill a single blade; but, alas! it frequently happens that he either visits all the blades, or is a.s.sisted by many individuals to each plant. This abundance we have observed more particularly on the breaking up of old pastures, old seeds, or saintfoin _lea_, in which not only have we many broods of wire-worms, but the eggs of a fresh lot, which hatch in time to eat the spring wheats. Again, this large increase we have ever observed in districts where rooks are few or much molested.

The rook is a constant visitor to the clover field; but when the plant is young he is driven off, because the farmer "cannot think what else he can come for but the clover buds;" and when he sees some of these strewing the ground where the birds have been, he is confirmed in his opinion: but, if he carefully looked at the buds themselves, he would find them of a sickly hue, however recent the attack, and, if he looked deeper he might find the real enemy.

Fortified, then, with repeated observations of this kind, if asked how best to keep under wire-worms, we say most unhesitatingly, encourage the rook: he is one of the farmer's best labourers; and though, like John, and d.i.c.k, and Hodge, he will sometimes run into mischief, it is surely better to inst.i.tute a judicious police than to condemn and execute without very strong evidence.

Yarrell, in his beautiful "British Birds," has the following remarks upon this highly-important subject:-

The attempts occasionally made by man to interfere with the balance of powers as arranged and sustained by Nature, are seldom successful. An extensive experiment appears to have been made in some of the agricultural districts on the Continent, the result of which has been the opinion that farmers do wrong in destroying rooks, jays, sparrows, and, indeed, birds in general on their farms, particularly where there are orchards. In our own country, particularly on some very large farms in Devons.h.i.+re, the proprietors determined, a few summers ago, to try the result of offering a great reward for heads of rooks; but the issue proved destructive to the farms, for nearly the whole of the crops failed for three successive years, and they have since been forced to import rooks and other birds to stock their farms with. A similar experiment was made a few years ago in a northern county, particularly in reference to rooks, but with no better success; the farmers were obliged to reinstate the rooks to save their crops.

But as, perhaps, the most interesting account of the value of rooks will be found in an extract from the _Magazine of Natural History_, vol. vi.

p. 142, we cannot do better than transcribe it:-

"In the neighbourhood of my native place (in the county of York),"

says the writer, Mr. T. c.l.i.thero, "is a rookery belonging to W.

Vavasour, Esq., of Weston, in Wharfdale, in which it is estimated that there are 10,000 rooks; that 1 lb. of food a week is a very moderate allowance for each bird, and that nine-tenths of their food consists of worms, insects, and their larvae; for, although they do considerable damage to the fields for a few weeks in seed-time, and a few weeks in harvest, particularly in backward seasons, yet a very large proportion of their food, even at these seasons, consists of insects and worms, which (if we except a few acorns and walnuts in autumn) compose at all other times the whole of their subsistence. Here, then, if my data be correct, there is the enormous quant.i.ty of 468,000 lb., or 209 tons, of worms, insects, and their larvae, destroyed by the rooks of a single rookery in one year. To everyone who knows how very destructive to vegetation are the larvae of the tribes of insects, as well as worms, fed upon by rooks, some slight idea may be formed of the devastation which rooks are the means of preventing."

Let this, then, suffice for the rooks; but starlings, wagtails, larks, and other birds, are also helpmates to the farmer; and therefore the wanton destruction of these will certainly bring, nay, has already brought, a great amount of trouble upon the cultivator of the soil.

The destruction we speak of has been committed by clubs and societies established for the purpose; but, as their members are mostly filled up with all sorts of prejudices-few being naturalists, or even accurate observers-it becomes daily a matter of more pressing importance that middle-cla.s.s education, if not National-school teaching, should recognise the value of the natural sciences.

2. The _Gout-fly_ (_Chlorops glabra_) and the _Saw-fly_ (_Sirex pygmaeus_) both lay their eggs below the first node or knot of the young plant, which, as soon as they hatch, form maggots that eat out the substance of the stems and the nodes, which thus become weakened and ultimately break off, or, if left standing, the ears of corn as they appear will be dried, whitened, and infertile.

In these, as in most cases of insect attacks, we have an occasional blight of such extent as to destroy whole crops, against which we are almost powerless, as we know so little of the economy of the creatures by whom the mischief is caused; still, there can be little doubt but that their periodical appearance, to the extent to cause them to be recognised as _blights_, is due to the thinning of their enemies; and we have always observed that a paucity of the _Hirundines_-the swallow tribe of birds, their greatest enemies-is coupled with a great increase of the smaller insects which it is the vocation of swallows, bats, and others of the hawking insectivorous creatures, to take on the wing.

3. The _Wheat-midge_ (_Cecidomyia tritici_), also called the Hessian-fly, is sometimes very destructive to the wheat crop. In 1860 we observed the effects of this creature to a greater extent than we have before known, in not a few instances rendering the crop scarcely worth reaping. Upon this creature we sent the following notice to the _Agricultural Gazette_ for August 30, 1862:-

The wheat-midge (_Cecidomyia tritici_) has been so destructive for the last two or three years, that every fact connected with its history ought to be of great interest. Curtis tells us that "in Scotland one-third of the crop was lost, and the farmers suffered severely in 1828 and the three following years;" whilst "in Suffolk the yield[19] of wheat was one-third less in some districts in 1841 than was expected."

[19] We believe this creature to be one of the most common causes of deficient yield, so that a knowledge of its history is all-important in estimating the value of a crop, which, as a rule, we should always put lower in the seasons when this blight abounds.

The presence or absence of this insect is so important as affecting the yield, that we now never fail to look for it in every crop upon which we would offer a judgment in this respect.

It is easily detected in the larva state on opening some of the chaff-scales-pales-of affected crops, as in the interior of these will be found some minute larvae (maggots) of a bright yellow or orange colour. In the earlier period of the blossom these larvae will be found about the stamens and pistils; later, upon the grain, which is always shrivelled and lost where the attack has been made.

The colour of the maggots is so much like that of the red-rust as often to be mistaken for it; the difference, however, between the bunches of minute granular fungi and living worms will be made apparent to the most careless observer by the a.s.sistance of a common pocket lens. We find two terms in use for these yellow appearances-namely, red-rust and red-gum; and as we have so often found them employed indiscriminately, we would restrict the former to the fungus,[20] thus-_Uredo rubigo_, red-rust; and _Cecidomyia tritici_, red-gum. Our observations on the latter this year have chiefly been made in the counties of Suss.e.x and Gloucester, in both of which we have seen this insidious enemy at work to an alarming extent. In the former county, with a very limited extent of red-rust; in the latter, the later and more delicate wheats have both red-rust and red-gum in the same crop: and the interest of the subject will be the more forcibly apprehended when we say that in some crops, which, from a first glance at the straw and ears, we should have put down as somewhere about thirty bushels per acre, we have, after a more minute inspection of the ears, estimated at less than twenty bushels; and, indeed, in one field which we have examined during the last week (August, 1862), affected by the _Cladosporium_, _Uredo_, and _Cecidomyia_, there will scarcely be a yield in good grains of the amount of the seed sown.

[20] See _ante_, p. 185.

The fly which lays the eggs from which these yellow larvae are derived is of about the size of a gnat, and usually takes the wing in the evening, in which case, if its enemies the bats are not numerous, smother fires lighted towards sundown on the wind side of the fields are not only destructive to large numbers, but act as an offensive notice to quit to others. Curtis says:-

With regard to the Hessian-fly, even if its presence could be ascertained in the early stages, it does not seem possible to devise any means of destroying the eggs or young larvae, unless feeding off the blade with sheep would effect the object; and when their progress is detected by their mischievous works, at a more advanced period, nothing, I apprehend, but sacrificing the crop would arrest them. It appears, therefore, to be an evil to which we must occasionally submit; but, to guard against its immediate recurrence, it will only be necessary to collect and burn the stubble after the corn is reaped, by which means the larvae and pupae which are concealed at the base of the stalk will, of course, be destroyed.

Now, in reference to wheat stubbles, we would remark that the old-fas.h.i.+oned plan of leaving them long as a protection, and, we may add, a preserve of food for partridges, had its good effects in an agricultural point of view; but if this be done, we advocate the burning of the stubs on the soil, as they will thus act better as a manure, while the destruction of insects by the process must be enormous. All concur that modern agriculture suffers increasingly from insects; hence, then, an extended study of their habits seems daily more desirable: and we boldly a.s.sert that if our country schoolmasters would teach their pupils to observe insect life, they may be doing more good to agriculture than all our present so-called agricultural colleges and schools put together.

4. The _Aphis flea_ (_Aphis granaria_) is a creature destructive to the grain by "sucking the verdure out on't." We have this year (1864) seen this insect, more especially the _apterous_-wingless-females, sticking on to the green wheat ears to such an extent as to render a walk into the crop a disgustingly dirty process. It would seem that a continuous dry and warm season favours the increase of these creatures; but, as we have always observed that the earlier sown wheats nearly always escape, from their coming into ear and advancing to ripeness before the aphis has increased its countless broods; so then we should recommend early wheat sowing, wherever and whenever practicable, as a preventive of the pest; in fact, the being in good time with all farm work has every advantage.

5. The two affections of the grain in our table are widely different in their modes of attack, but both tend to lessen the quant.i.ty of produce.

The first, the Ear-c.o.c.kle (_Vitrio tritici_) is an affection of the grain, which at starting it will be well to distinguish from s.m.u.t or bunt. In the latter, the grain is filled with what appears a black powder, the grains of which the microscope shows to be a fungus;[21]

whilst in the c.o.c.kle the seed, which is purple externally-hence called "purples"-is filled with what appears to be white cotton wool. This, under the microscope, has the appearance of a mult.i.tude of eels. These are, indeed, minute infusorial worms, and are exceedingly curious; the smallest portion of the cottony substance taken on a pin's point and just moistened with water, often showing thousands of the eels under a good instrument; for drawings and descriptions of which and good drawings (after Bauer), we should recommend the reader to consult "Curtis's Farm Insects." A damp season favours the production of these; hence drainage and such conditions as increase the effects of damp and cold are to be guarded against.

[21] See _ante_, p. 183.

The _Corn Moth_ is best known by the presence of a small, slightly hairy maggot, which is found to eat the flour from the grain; this is the larva of a small moth, probably the _Butalis cerealella_. It is easily found in the chaff scales; and during the summer of 1861 we saw as many as six in a single ear, and it was, indeed, one of the causes of the bad yield of that year. We know of no remedy for this evil; but, perhaps, if we were better acquainted with the habits of the moth itself, means might be devised for taking it before the eggs are laid in the young ear of corn.

6. The _Corn or Granary Weevil_ (_Calandra granaria_) and others.-These attack corn in store, and probably differ in species according to the kind of corn. This is a small beetle, the female of which makes a hole in the grain and deposits an egg, which soon hatches into the maggot; this eats out the grain with great a.s.siduity until its partial period of rest in the pupa state; which pa.s.sed, the beetle finishes the work, and may frequently be found in the interior of wheat.

The usual structures of granaries and corn-stores contribute to the increase of this pest, as they are mostly dark and ill-ventilated chambers. The best remedy is to expose the grain to the greatest possible amount of cold, by spreading it on the floors in hard frosts, and letting in light and air. Curtis quotes the "Bulletin des Sciences Agriculture" for July, 1826, for the following plan:-"Lay fleeces of wool, which have not been scoured, on the grain; the oily matter attracts the insects amongst the wool, where they soon die, from what cause is not exactly known. M. B. C. Payrandeau related to the Philomatic Society of Paris that his father had made the discovery in 1811, and had since practised it on a large scale."

7. The moth that visits granaries (_Tinia granella_) may here be adverted to. The presence of the larvae of the little grain moth may soon be ascertained in the granary, when one finds several grains of corn united by a web, to which will be attached bunches of small granules, which are the exuviae of the one or two caterpillars belonging to each group of corns.

The best method of preventing this is thorough cleanliness, light, and ventilation in the granary. If, however, the moth has got possession, then we recommend sulphur to be burnt in iron pans-old saucepan lids are as good as anything-stopping up all the crevices. This will be an effectual remedy, not only for the moth, but for the weevils and other insect pests; and if a pound of sulphur be occasionally burnt in the barn, even rats must succ.u.mb to the gas which is generated.

8. The _Meal-worm Beetle_ (_Tenebrio molitor_), which generates commonly in the meal-bins of this country, and the _T. obscurus_, which has been introduced in American flour, are two forms of beetle, the larvae of which are "meal-worms." These are best prevented by not keeping too large a store of flour, always having this dry and in the best condition, and storing, as far as possible, in a clean, light, and airy position. Indeed, as Curtis remarks, "Cleanliness is the best guard against these insects;" and we cannot better conclude this chapter than by further quoting the following from this excellent author:-

In looking back to the variety of insects that feed upon corn, and the mult.i.tudes that are often congregated in one heap, there can be no doubt that a very large portion must be occasionally ground up with the corn and consumed by the public. This is not only a disagreeable fact, but it may be the source of very serious consequences, for I think it not improbable that many diseases might be traced to the insects which are converted with the infested flour into bread, amounting to such a large percentage, that if they have the slightest medicinal or deleterious qualities, it is impossible to deny the influence they must exercise upon the human system. I have known bushels of cocoa-nuts, which were every one worm-eaten and full of maggots, with their webs, excrement, cast-off skins, pupae, and coc.o.o.ns, all ground down to make chocolate, flavoured, I suppose, with vanilla!

CHAPTER x.x.x.

SCIENCE IN THE CULTIVATION OF CORN.

The object of the present chapter will be to point out the principles concerned in the more immediate acts connected with the cultivation of corn. In so doing in the present case, as in the discussion of the preceding subjects, it may not be out of place here to state that it has not, nor will it be, our object to enter into the every-day practical details of crop-management, but to dwell more particularly upon those points in cultivation which may be said to belong more especially to the science of the subject.

This chapter, then, will be more especially devoted to the consideration of the three following subjects:-

1st. On the uses of special manures for corn crops.

2nd. On the quality and quant.i.ty of corn to be used for seed.

3rd. On the period for harvesting corn.