Science and Practice in Farm Cultivation Part 22

_Bunt._ _Ear-c.o.c.kle._

Grain smooth externally, sometimes Grain c.o.c.kled and irregular in appearing black from blackened shape, purple externally, skin interior grains showing through thickened, interior of the grains the thin epidermis (bran). These stuffed with a white cottony corns easily crush beneath the substance, not compressible by finger, emitting the black fungi. the finger; but being opened, and the interior magnified, exhibits the living wheat-eels.

As regards the ear-c.o.c.kle, we incline to the belief that a damp atmosphere and cold soil are chiefly concerned in its spread, if not in its production. As we have shown the difference between it and bunt, we now proceed to offer a few remarks upon the production of the latter, and its remedies.

Bunt is mainly produced by defective seed. It occurs on all kinds of soils-sands, clays, and limestones-and is not peculiar to any climate.

Professor Henslow believes the disease to be wholly propagated by the spores of the fungus adhering to the wheat-seed. He says, "It has been clearly proved that wheat plants may be easily infected, and the disease thus propagated, by simply rubbing the seeds before they are sown with the black powder or spores of the fungus. It is also clearly ascertained that if seeds thus tainted be thoroughly cleansed, the plants raised from them will not be infected;" and he deduces from this a proof in favour of steeping; for he says, "This fact is now so well established, that the practice of was.h.i.+ng or steeping seed wheat in certain solutions almost universally prevails."[17]

[17] See an essay on _Diseases of Wheat_, in the _Journal of the Royal Agricultural Society_ for 1841, by the Rev. Professor Henslow.

Our own experiments, however, recorded in the "Journal of the Royal Agricultural Society" for 1856, led us to conclude that the success derived from pickling wheat in different caustic and corrosive solutions arose from the fact of diseased grain being destroyed in the process; and we extract the following record of experiments made in 1853, as explaining this view of the matter.

Four plots of wheat, all from the same sample, were sown in the following order:-

1. 2. 3. 4.

+---------------++---------------++---------------++---------------+ Much diseased Much diseased; Perfect picked Perfect picked wheat, treated with seed, seed, with without pickle. sulphate of without pickle. sulphate of copper. copper. +---------------++---------------++---------------++---------------+

The results of these were as under:-

Plot 1. Most of the seed germinated, but the crop was much blighted, both in straw and grain; in fact, scarcely a perfect ear of the latter.

Plot 2. A small quant.i.ty of the seed germinated; the few resulting ears were free from blight.

Plot 3. Germinated, with a good and clean resulting crop.

Plot 4. The same result as Plot 3.

These experiments seemed to show that the pickling of wheat destroys the seed, so as to prevent germination when the seed is diseased or ill-formed; but if perfect seed be always employed, no pickling at all is necessary, it being strictly true that a diseased progeny must result from an imperfect stock in plants no less than in animals.

We have said that bunt is not peculiar to any climate; we have, however, always observed that employing seed from a warm district on a cold one, or using the finer white wheats in cold, exposed, or ill-drained situations, is sure to produce a large quant.i.ty of this fungus.

Autumn-sown wheat, too, is less liable to the infection than spring wheat, which we attribute to the fact that many of the weaker plants will succ.u.mb to the cold rain and frost.

3. _Uredo rubigo_ (Red-rust, Red-rag, Red-robin) makes its appearance in the inside of the chaff-scales, and ultimately in the green epidermis of the growing grains of wheat. Its first appearance is that of oval pustules, caused by the raising of the skin, which, ultimately bursting, shows the orange-coloured spores of the epiphyte. This must not be confounded with _Cecidomyia tritici_ (wheat-midge), the larvae of which are of a bright orange-colour; in the latter, the living moving worms may be easily detected by any common pocket lens or magnifying gla.s.s.

Both these pests, to which we would apply the distinctive terms of _Uredo rubigo_ (red-rust) and _Cecidomyia tritici_ (red-gum), are exceedingly common in some seasons, and not unfrequently in the same crop. Good deep cultivation is the best remedy for the rust; but the treatment of the fly is a different matter. We would suggest the burning of smother-heaps on calm days, just as the wheat is bursting into ear, as smoke is decidedly obnoxious to these small insects, which in some seasons may be seen in thousands about the bursting wheat.

4 and 5. _Uredo linearis_; _Puccinia graminis_ (Straw-rust and Mildew).-We refer to these epiphytes under one heading, as there can be but little doubt that the latter is a more advanced state of the former.

They both occur in oblong patches on the leaves and straw of wheats and other gra.s.ses: in the _uredo_ stage, of a dull red colour; in the _puccinia_ stage, of a blackish hue. They are both, as, indeed, are all these fungi, interesting microscopic objects; but our object now is to describe them popularly. Both will always be found in abundance in cold poor soils, and more especially if the finer wheats be grown in such situations. The application of a dressing of salt to the soil is said to be a preventive. Be this as it may, the disease is said to be rarer in Ches.h.i.+re, where salt is so much used by the farmer, than in any other county, in as far as we have observed.

Here, again, we incline to think that these are morbid affections of the plant. They are, indeed, viewed as such by Unger, in his "Die Exantheme Pflanzen," in which the very t.i.tle cla.s.ses them with eruptive diseases of animals. Berkeley and Henslow, the two great authorities, however, do not accord with this view: the former remarks in reference to it-"Surely these plants are too distinctly, too regularly, and too beautifully organized to be the products of disease like warts or purulent matter in animals." As, however, the microscope demonstrates that warts and eruptive diseases have also their special and curiously formed organisms, such a mode of reasoning is not conclusive.

Weeds have a great influence in producing mildew, which perhaps may be accounted for from the fact that weeds are in active growth as the wheat-stalks decline in vigour; and hence the constant evaporation of moisture from the weeds to the wheat is continually re-moistening an ever-drying surface-a most fertile source of mildew and moulds of several descriptions.

6. _Puccinia fabae_ (Bean-rust).[18]-The brown pustular rust-looking spots on the foliage of beans, and, indeed, occasionally on the stems and pods of beans, are sometimes common to this crop. They are usually accompanied by a lessening both in quant.i.ty and quality of this pulse, both in the garden and in field culture, but certainly more generally in the latter. Too gross manuring without well mixing the dung with the soil would seem to be a constant source of the evil. In fact, highly nitrogenized manures appear to favour the development of all this cla.s.s of epiphytes, just as too much meat might bring about different forms of rash or eruptions in the animal. Weeds, which are too much permitted in beans, here aid in perfecting the mischief; hence, then, we may perhaps take it for granted that the mention of the causes of mischief suggests the remedy.

[18] This blight is mentioned here on account of its affinity to the former.

7. _aecidium berberidis_ (Barberry-rust) is here referred to, from the opinion prevailing that it is the cause of rust and mildew in wheat. We can no more believe that the barberry-rust would produce rust in wheat, than the rust of any other plant would do so; for nearly all plants are affected with some kind or other of rust. This epiphyte, too, is very different in structure from wheat-rust. Still, that wheat growing under a barberry hedge may be more blighted than in the rest of the field is quite true; and so it is with wheat grown under any kind of hedge. High fences are known to favour wheat blights; open, exposed, well-cultivated positions, when not too elevated, and without trees or hedges, being those in which the best wheats are grown.

8. _Cladosporium herbarum_ (Corn-ear Mould) is a brown-coloured mildew, mostly occurring on the exterior of the chaff-scales of wheat, but common to many plants in a state of decadence. It consists of greenish or blackish tufts, which appear on the outside of the chaff-scales of wheat under the two following conditions:-

On wet soils, where the ears appear to have been prematurely starved.

On dry sands, where long-continued drought has caused some ears to wither and die before the seed was fully formed.

In both these cases we see that the plant has been previously injured.

The decay commences under alternations of moisture and drying, and hence the fungoid attack. Here, then, the conditions necessary for preventing will be deep cultivation and a due pulverization and mixture of the soils.

9-12. _Botrytis_, _&c._ (Mildew).-Under this head we include a mult.i.tude of epiphytes, to which the terms mildew, mealdew, mehlthau (Germ.) are applicable. They appear to the naked eye as patches of white dust or meal on the leaves and stems of the affected plants. With the microscope we see that they are beautifully-organized plants, having a kind of rootlet (mycelium) or sp.a.w.n entering the tissues of the living plants on which they grow, and delicate pedicels supporting spores at the externally visible portion of the plant. The botrytis of the potato and turnip, the erysiphe or odium of the hop, vine, and other plants, are only different forms of mildew, which in some shape or another will be found on most plants. That these attack living tissues is quite certain; but in the case of the potato, the turnip, and the vine, there is reason to believe that they result, to a very considerable extent, from diseased action in their tissues. For example: the botrytis of the potato seems to attack a crop much over-cultivated, on the approach of wet and cold nights after a prosperous growth in warm suns.h.i.+ne. So, the odium seems to us to be most abundant on renewed growth after a season of dry weather. Again: mildew in turnips is sure to follow that check which a long season of dry weather brings after a prosperous and vigorous growth. All these circ.u.mstances at least show how these attacks are favoured by the conditions which bring disease. So much, indeed, is this the case, that we found, upon experimenting with some cuc.u.mbers in a warm stove, that as long as we regularly watered the plants and gave them the requisite air, they kept healthy; but, by neglecting these conditions for a few days, we obtained mildew with the greatest certainty.

The remedies against mildew are-to obtain as healthy a growth as possible, and to maintain this with as great regularity as circ.u.mstances will permit. Of late years, both the mildew of the vine and the hop have been treated with flowers of sulphur. Dusting the affected hop-leaves with sulphur certainly arrests the mildew in an incredibly short time; and we found that by dusting sulphur from a fine sieve on our cuc.u.mber plants, the disease was immediately arrested in its progress. We therefore look upon this as an invaluable remedy in these states of mildew, whether occurring on the vine, the hop, the turnip, the cuc.u.mber, or on other plants, as we have frequently seen it in hothouses-a circ.u.mstance which shows the near affinity of all those forms of epiphytes, which, perhaps, after all, only vary with the variations in the structure and economy of the different plants on which they occur.

13. _Odium abortifaciens_ (Ergot); _Secale cornutum_ (Ergot of Rye).-The black horn-looking spur which occurs in rye and other gra.s.ses was formerly looked upon as a distinct fungus; now, however, it is known to be a diseased or malformed condition of the grain or seed, resulting from an attack by an odium on the immature seed.

Most of the cereal and even the meadow gra.s.ses are liable to attacks of ergot, which is increased by cold damp fogs and a moist condition of the atmosphere, the difference of the size of the spur being in accordance with the size of the affected gra.s.s seed. Thus, in rye we have seen spurs more than an inch long, while in the c.o.c.k's-foot gra.s.s it is seldom a quarter of an inch.

The ergot, as it occurs in the rye, is much used by medical men in difficult cases of parturition; and we have had evidence before us, in some cases of abortion in cows, that the constant depasturing on gra.s.ses affected with ergot (and the _Lolium perenne_ in aftermaths is often especially so) has been the predisposing cause.

CHAPTER XXIX.

INSECTS (ANIMAL BLIGHTS) AFFECTING CORN CROPS.

The different families and species of insects affecting the various kinds of corn crops in all their stages of growth are so numerous, that a detailed list of them would occupy greater s.p.a.ce than we can devote to this chapter.

In this position of affairs we have thought it wise to confine our remarks to some of the commoner and more mischievous species, choosing those more particularly which are common to the wheat crop, of which the following may be at once introduced as a summary in itself sufficient to show what the farmer may expect at each stage of growth:-

1. { The _Slug_, } Attacking the plants soon after germination.

{ The _Wire-worm_, }

2. { The _Gout Fly_, } That attacks the wheat stems as they begin to { The _Saw Fly_, } form.

3. The _Wheat Midge_-Commencing their injuries in the young flower.

4. The _Aphis Flea_-Which attacks the _rachis_ and floral envelopes.

5. { The _Ear c.o.c.kle_, } Which destroys the growing grain.

{ The _Corn Moth_, }

6. The _Corn Weevil_-Which eats the flower from the grain.

7. The _Little-grain Moth_-Which attacks the grain in store.

8. The _Meal-worm Beetle_-Living upon ground corn or flour.

Now, this list may be said to have reference to eight stages in the growth and preparation of wheat, and they mostly apply to other grains also-namely, 1. The germinating plant; 2. The growing plant; 3. The growing flower; 4. The green ear of corn; 5. The young grain; 6. The perfected grain; 7. The stored grain; and 8. In the state of flour.