Wheat is blighted at Two Seasons; First, when in the Blossom; and then its Generation is prevented and many of the Husks are empty in the Ear, the Grains not being impregnated.
Secondly, Wheat is blighted, when the Grains are brought to the time of their Maturity, but are light, and of little Value for making of Bread; because they are not well filled with Flour.
The First cannot happen in England by the Frost because the Winters do not suffer it to grow so much, as to come into Blossom before the Month of June; but they are long continual Rains that rot or chill the Blossoms, and prevent their Fertility. Yet this is what seldom happens to any great Degree. Wheat that grows in open Fields has some Advantage from the Wind, that dislodges the Water sooner from the Ears, than it can do in sheltry Places; and Lammas Wheat does not hold the Drops of Rain so long as the Bearded (or Cone) Wheat, which received very great Damage by this sort of Blight in the Year 1725, the like never having been heard of before.
The Second sort of Blight, viz. from light Ears, is that which is most frequent, and more general: This brings the greatest Scarcity of Wheat. The Cause is plainly Want of Nourishment to perfect the Grain, by whatever means that Want is occasioned.
Several Accidents kill the Plants, or injure their Health, and then the Grains are not filled; as Lightning, the Effects whereof may be observed by the blackish Spots and Patches in Fields of Wheat, especially in such Years as have more of it than usual. Against this there is no Defence.
The other Causes of the Blight, which are most general, and do the most Damage, may, in some measure, be prevented.
One Cause is the lodging or falling of Corn; for then the Stalks are broken near the Ground, whereby many of the Vessels are so pressed, that the Juices cannot pass them; and then the free Circulation is hindered; the Chyle cannot mount in sufficient Quantity to be purified, and turned into Sap; the Defect whereof makes the Plants become languid, and only just able to live; they have Strength enough to linger on to the time of their Period, as in very old Age, but not to bring their Fruit, which is the Grain, to its natural Bulk, nor to fill it with Flour: and the sooner the Stalks fall, the less and thinner the Grain will be.
Hence it often happens, that when Tillage, Dung, and good Land have brought a Crop of Wheat, that in the Months of April and May promise to yield the Owner Five or Six Quarters on an Acre, then in June it falls down, and scarce affords Five or Six Bushels; and that perhaps is so thin and lank, that the Expence of reaping and threshing it may overbalance its Value.
That the falling down of Wheat does cause the Ruin of the Crop, is well known; but what causes it to fall, is not so plain.
And, without knowing the true Causes, ’tis not likely that a Remedy should be found against the Disease.
I take this Weakness of the Stalks, which occasions their falling, to proceed from want of Nourishment, want of Air, want of the Sun’s Rays, or of all Three.
One Argument, that it lodges for want of Nourishment, is, that a rich Acre has maintain’d a Crop of Five Quarters standing, when another poorer Acre was not able to support a Crop from falling, which was but large enough to have brought Three Quarters, if it had stood: and this in the same Year, and on the same Situation. And ’tis very plain, that if one Acre was twice as rich as the other, it must be able to nourish Five Quarters better than the other could nourish Three Quarters.
Air is necessary to the Life and Health of all Plants, tho’ in very different Degrees: Aquatics, which live under Water, are content with as little Air, as their Companions the Fishes.
But Wheat, being a terrestrial Plant, (tho’ in Winter it will live many Days under Water, whilst the slow Motion of its Sap gives it little or no Increase), requires a free open Air, and does not succeed so well in low sheltery Places, as upon higher and opener Situations; where the Air has a greater Motion, and can more easily carry off the Recrements from the Leaves, after it has shaken off the Dews and Rains, which would otherwise suffocate the Plants; and therefore the Leaves are made so susceptible of Motion from the Air, which frees them from the Dews, that would stop in the Recrements at the Vesiculæ of the Leaves, but shaken down will nourish the Plants at the Roots: The want of this Motion weakening the Wheat, ’tis (as Animals in the like sickly Case are) the more unable to stand, and the more liable to be press’d down by the Weight of Rain-water, and more unable to rise up again when down: All which Evils are remov’d by the free Motion of the Air, which shakes off both Dews and Rains, and thus contributes to prevent the falling (or lodging) of Wheat.
A great Quantity also of the Sun’s Rays is necessary to keep Wheat strong, and in Health; and in Egypt, and other hot Countries, it is not so apt to fall, as it is when sown in Northern Climates, tho’ the Produce of the South be the greatest[152].
[152]This proves that the Crop doth not lodge on account of its Bigness.
It may be observ’d, that every Leaf is inserted into a Sort of Knot, which probably delivers the Sap to be depurated at the Vesiculæ of the Leaves, and then receives it back again for the Nourishment of the Plant, doing for that Purpose the Office of an Heart: But the Sun with his Rays supplies the Part of Pulse, to keep the Sap in Motion, and carry on its Circulation, instead of the Heart’s Systole and Diastole. Wheat, being doubtless originally a Native of a hot Country, requires by its Constitution a considerable Degree of Heat to bring it to Perfection; and if much of that Degree be wanting, the Wheat will be the weaker; and when the Solar Rays cannot reach the lower Parts of the Stalks, the lowest Leaves and Knots cannot do their Office; for which Reason the Chyle must mount higher before it be made into Sap, and there must be then a greater Mixture of crude Chyle next to the Ground, as by the white Colour it appears[153]. By this Means that Part, which, if it had a due Share of the Sun’s Influence, would be harden’d like a Bone or Spring, for the Support of the Stalks, for lack of that, becomes more like to a Cartilage, soft and weak, unable to sustain the Weight of the bending Ear, which, having its greatest Impetus against this Part, which is most feeble to resist it, it yields, and lets it fall to the Ground; and then the Grain will be blighted.
[153]But now I suspect this to be a Mistake, it being more likely, that the white Colour of the Rind is owing to the Absence of the Sun and free Air, than to the Chyle, as the Skin of those Parts of our own Bodies that are concealed from them, is whiter than of those which are exposed to them, though no Chyle-vessel comes near our Skin.
There is also another Cause of the Blight; and that is, the Wheat’s coming too late into Blossom. The usual Time is the Beginning of June; and if it be later, the Days shorten so fast after the Solstice, that the Autumn of the Year hastening the Autumn of the Wheat’s Life, the full Time of its Pregnancy[154] is not accomplish’d; and then its Fruit, which is the Grain, becomes as it were abortive, and not full-grown. This Time betwixt the Generation, Blossoming, and the Maturity of the Grain, is, or ought to be, about Two Months.
[154]Ut enim Mulieres habent ad Partum Dies certos, sic Arbores ac Fruges. Varro, Lib. 1. Cap. 44.
Mense Maio florent; sic Frumenta, & Ordeum, & quæ sunt Seminis singularis, Octo diebus florebunt, & deinde per Dies 40. grandescunt Flore deposito usque ad Maturitatis Eventum. Palladius, Pag. 114, 115.
Quindecim Diebus esse in Vaginis, Quindecim florere, Quindecim exarescere, cum sit maturum Frumentum. Varro, Lib. 1. Cap. 32.
But the different Heat that there is in different Climates, may alter both the Time that Plants continue in Blossom, and the Time betwixt the Blossoming and the Ripening.
Therefore ’tis advantageous to hasten, what we can, the Time of Blossoming, and to protract the Time of Ripening: And ’tis observ’d, that the earliest sown Wheat generally escapes the Blight the best, because it comes first into Blossom.
Feeding down the Wheat with Sheep prevents the Blight, by doing what the Blight wou’d do, if the Wheat fell down, i. e. causes the Ears to be light[155].
[155]Heavy Ears never fall. If they did, that would not make them light. Wheat falls sometimes whilst ’tis in Grass, and before it comes into Ear; so far are the Ears from causing it to fall. This was proved by my whole Crop the last Harvest, and particularly by the Measured Acre, the Ears of which, tho’ prodigious large and heavy, were none of them lodg’d, when those of sown Wheat on the other Side of the Hedge were fallen down flat, and lodg’d on the Ground.
And we find, that those who practise this Method of feeding their Wheat with Sheep in the Spring, to prevent the lodging of it, have most commonly their Straw weak, and Ears light.
These, instead of making the Stalks strong enough to support heavy Ears, make the Ears light enough to be supported by weak Stalks. They know that heavy Ears make the greatest Crop; and yet they still hope to have it from light ones.
They cause the Blight by the very means they make use of to cure it.
This feeding of Wheat much retards the Time of its blossoming; and that it may blossom early, is one chief End of sowing it early, to prevent the Blight. But when it is fed, what the Plants send up next is but a Sort of second or latter Crop, which has longer to stand than the first would have required, and is always weaker than the first Crop would have been; and the longer time it has to continue on the Ground, the more Nourishment is required to maintain it; and yet, as has been shewn, the longer it has been sown, the more the Earth has lost of its Nourishment; and consequently, the Crop will be yet weaker, and in more Danger of the starving Blight[156].
[156]I am sure, that whenever Sheep break into my drill’d Wheat in the Spring, it lessens my Crop half, just as far as they eat the Rows. There are several Reasons why Sheep are more injurious to drilled Wheat than sown; I would not therefore be understood to decry the Practice of seeding sown Wheat, when the Thickness and Irregularity of its Plants make it necessary: I have only endeavoured to shew, that that Practice is founded upon a false Theory. For, if Wheat fell down by reason of the Luxuriance of it; a Plant of it would be more likely to fall when single, and at a great Distance from every other Plant, than when near to other Plants, because such a single Plant is (cæteris paribus) always the most luxuriant; and I have not seen such a one fall (except Birds pull down the Ears), but have observed the contrary, though its Ears are the largest.
The Subject I write on is Drilling and Hoeing, and of whatsoever else I think relates to the Practice or Theory thereof; which obliges me to advise against Drilling too thick upon any Sort of Land; but more especially upon very rich Land: For though I have no such Land, yet I apprehend, that a too great Number of Plants may overstock the Rows, and cause them to be liable to some of the Inconveniences of sown Wheat; and in such a Case, perhaps, Sheep may be rather useful than prejudicial to the drilled Wheat; but of this I have had no Experience: And if it should be too thick, it will be owing to the Fault of the Manager or Driller; but, I suppose, it might be a better Remedy to cut out the superfluous Plants by the Hand-hoe, in the manner that superfluous Turneps are hoed out.
The most effectual Remedy against the Blight is that which removes all its Causes (except such extraordinary ones as Lightning); as,
The Horse-hoe will, in wide Intervals, give Wheat, throughout all the Stages of its Life, as much Nourishment as the discreet Hoer pleases.
Air, being a Fluid, moves most freely in a right or strait Line; for there the fewest of its Parts meet with any Resistance; as a strait River runs swifter than a crooked one, from an equal Declivity; because more of the Water strikes against the Banks at the Turnings, and is there somewhat retarded: and the rest moving no faster than in the strait River, the whole Stream of the crooked must be slower in its Course, than that of the strait River.
The Air cannot pass thro’ sown Corn in a direct Line, because it must strike against, and go round every Plant, they standing all in the Way of its Course, which must stop its Current near the Earth.
And the Air amongst sown Corn is like Water amongst Reeds or Osiers in the Side of a River; it is so stopp’d in its Course, that it almost becomes an Eddy; and since Air is about Eight hundred Times lighter than Water, we may suppose its Current thro’ the Corn is more easily retarded, especially near the Earth, where the Corn has occasion for the greatest Quantity of Air to pass: For, tho’ the upper Part of the Wheat be not able to stop a slow Current of Air, yet it does so much raise even a swift one, as to throw it off from the Ground, and hinder it from reaching the lower Parts of the Stalks, where the Air must therefore remain, in a manner, stagnant; and the thicker the Wheat is, where it stands promiscuously, the less Change of Air can it have, tho’ the greater the Number of the Stalks is, the more fresh Air they must require.
But the confused Manner in which the Plants of sown Wheat stand, is such, that they must all oppose the free Entrance of Air amongst them, from whatever Point of the Compass it comes.
Now it is quite otherwise with Wheat drill’d regularly with wide Intervals; for therein the Current of Air may pass freely (like Water in a strait River, where there is no Resistance), and communicate its Nitre to the lower as well as upper Leaves, and carry off the Recrements they emit, not suffering the Plants to be weakened, as an Animal is, when his Lungs are forc’d to take back their own Expirations, if debarr’d from a sufficient Supply of fresh untainted Air. And this Benefit of fresh Air is plentifully, and pretty equally, distributed to every Row in a Field of ho’d Wheat.
Sown Wheat-plants, by their irregular Position, may be said to stand in one another’s Light, for want of which they are apt to fall.
’Tis true the whole Field of Plants receive the same Quantity of Sun-beams amongst them, whether they stand confusedly, or in Order: But there is a vast Difference in the Distribution of them; for none or the very least Share of Beams is obtain’d by those Parts which need the greatest Share, in the confused Plants. And when the crural Parts, that should support the whole Body of every Plant, are depriv’d of their due Share of what is so necessary to strengthen them, the Plants (like Animals in the same Case) are unable to stand.
But in drill’d Wheat, where the Plants stand in a regular Order, the Sun-beams are more duly distributed to all Parts of the Plants in the Ranks; for which Way soever the Rows are directed, if they be strait, the Rays must, some time of the Day, fall on the Intervals, and be reflected by the Ground, whence the lower Parts of the Wheat-stalks must receive the greater Share of Heat, being nearest to the Point of Incidence, having no Weeds to shadow them.
As to that Cause of the Blight, viz. the Wheat’s dying before the full Time of its Pregnancy be accomplish’d; the Hoe removes all the Objections against planting early, and then it will blossom the earlier: And it has visibly kept Wheat green a whole Week longer, than unho’d Wheat adjoining to it, planted the same Day.
The Antients were perfect Masters of the Vine-Husbandry, which seems to have so engross’d their rural Studies, that it did not allow them so much Reflection, as to apply the Use of those Methods to the Increase of Bread, which they had discover’d to be most beneficial for the Increase of Wine. One Method was, to hoe the Vines after they had blossom’d, in order to fill the Fruit, as in Columella, Lib. iv. Cap. 28. Convenit tum crebris Fossionibus implere: nam fit ulterior Pulverationibus. And if what Palladius says, Tit. ix. be true of the Sarritions and Sarculations in the Month of January, and that if Beans do twice undergo that scratching Operation, they will produce much Fruit, and so large as to fill the Bushel almost as full when shal’d as unshal’d.
Faba, si bis sarculetur, proficiet, & multum Fructum & maximum afferet, ut ad Mensuram Modii complendi fresa propemodum sicut Integra respondeat.
This is to be done when Beans are Four Fingers high, and Corn when it has Four or Five Leaves to a Plant; even then the Harrowing-work, tho’ it tore up some of the Plants, yet it was observ’d to do Good against the Blight.
Si siccas Segetes sarculaveris, aliquid contra Rubiginem præstitisti, maxime si Ordeum siccum sarrietur.
When the Antients observ’d this, ’tis a Wonder they did not plant their Corn so as to be capable of receiving this Benefit in Perfection. They might have imagin’d, that what was effectual against the Blight, when the Corn was in Grass, must, in all Probability, be much more effectual when in Ear.
But the most general Blight that happens to Wheat in cold Climates, is caused by Insects, which (some think) are brought in the Air by an East Wind accompanied with Moisture, a little before the Grain is filling with that milky Juice, which afterwards hardens into Flour. These Insects deposit their Eggs within the outer Skin (or Rind) of the Stalks; and when the young ones are hatched, they feed on the Parenchyma, and eat off many of the Vessels which should make and convey this Juice; and then the Grain will be more or less thin, in Proportion to the Number of Vessels eaten, and as the Insects happen to come earlier or later; for sometimes they come so late, that the Grain is sufficiently fill’d with the said milky Juice before the Vessels are eaten; and then, tho’ the Straw appear thro’ a Microscope to have its Vessels very much eaten and torn, and to be full of black Spots (which Spots are nothing else but the Excrements of those young Insects), yet the Grain is plump, and not blighted, there being an Observation, That the early sown Wheat generally escapes this Blight. And it has been seen, where one Part of a Field is sown earlier than the other Part, without any other Difference than the Time of sowing, that the Grain of the latest sown has been much blighted, and the Grain of the earlier has escaped the Blight, tho’ the Straw of both were equally eaten by the Insects. Hence it may be inferr’d, that the Milk in the one had receiv’d all the Nourishment necessary to its due Consistence, before the Vessels were destroy’d; but, in the other, the Vessels, which should have continued the Supply of Nourishment for thickening the Milk, being spoil’d before they have finish’d that Office, it remains too thin; and then the Grain, when it hardeneth, shrinks up, and is blighted; yet the Grain of one and the other are equally plump until they become hard: The Difference therefore is only in the Thickness of the Milk, that in the blighted being more watery than the other.
The chief Argument to prove, that these Insects are brought by an East Wind, is, that the Wheat on the East Sides of Hedges are much blighted, when that on the West Sides is not hurt: And as to the Objection, that they are bred in the Earth, and crawl thence up the Stalks of the Wheat, because some Land is much more subject to produce blighted Wheat than other Land is; perhaps this Difference may be chiefly owing to the different Situation of those Lands, as they are opposed to the East, or to the West.
Another Cause why some Wheat is more blighted than other Wheat on the same Land, is, the different Condition in which the Insects find it; for the Rind of that which is very strong and flourishing[157] is soft and tender; into this they can easily penetrate to lay their Eggs; but the Wheat that is poor and yellow, has an hard tough skin (or Rind), into which the Insects are not able to bore for the Intromission of their Eggs, and therefore can do it no Mischief. It would be in vain to advise to prevent the Blight, by striving to make the Wheat poor; for tho’ Poverty may preserve Wheat from this Blight, as well as it does People from the Gout, yet that is a Remedy which few take willingly against either of these Diseases: But this, I think, might be possible to remedy it, if we could, from the strongest Wheat, take away so much Nourishment as to turn its Colour[158] a little yellowish just before the Insects come[159] which I suppose to be in June, after the Ear is out, or at least fully formed.
[157]Some Sort of Land is more subject to this Blight than others; in such, Lammas Wheat must by no means be drill’d late, and too thin, lest it should not tiller till late in the Spring; and then, for want of a sufficient Quantity of Stalks to dispense with all the Nourishment rais’d by the Hoe, may become too vigorous and luxuriant, and be the more liable to the Injury of the Blight of Insects.
[158]But this is a very difficult Matter.
[159]Whither those Insects go, or where they reside, from the Time of their eating their Way out of the Straw, until they return the next Year, I cannot learn.
Yet this can only be done in wide Intervals; for, unless the fine Earth can be thrust to some considerable Distance from the Roots after they are cut off, they will soon shoot out again, and reach it, becoming more vigorous thereby.
In dry Summers this Misfortune seldom happens, much Heat, and very little Moisture, being most agreeable to the Constitution of Wheat; for then its Rind is more firm and hard, as it is, on the contrary, made more soft and spongy by too much Moisture.
The most easy and sure Remedy, that I have yet found against the Injury of these Insects, is, to plant a Sort of Wheat that is least liable to be hurt by them; viz. The White-cone (or bearded) Wheat, which has its Stalk or Straw like a Rush, not hollow, but full of Pith (except near the lower Part, and there ’tis very thick and strong): ’Tis probable it has Sap-Vessels that lie deeper, so as the young Insects cannot totally destroy them, as they do in other Wheat: For when the Straw has the black Spots, which shew that the Insects have been there bred, yet the Grain is plump, when the Grey-cone and Lammas Wheat mixt with it are blighted. This Difference might have been from the different times of ripening, this being ripe about a Week earlier than the Grey-cone, and later than the Lammas: But its being planted together both early and late, and at all Times of the Wheat-seed Time, and this White-cone always escaping with its Grain unhurt, is an Argument, that ’tis naturally fortify’d against the Injury of these Insects, which in wet Summers are so pernicious to other Sorts of Wheat; and I can impute it to no other Cause than the different Deepness of the Vessels, the Straw of other Wheat being very much thinner, and hollow from Top to Bottom; this having a small Hollow at Bottom, and there the Thickness betwixt the outer Skin and the Cavity is more than double to that in other Sorts of Wheat; so that I imagine, the Insects reach only the outermost Vessels, and enough of the inner Vessels are left untouch’d to supply the Grain.
This Wheat makes very good Bread, if the Miller does not grind it too small, or the Baker make his Dough too hard, it requiring to be made softer than that of other Flour.
A Bushel of this White-cone Wheat will make more Bread than a Bushel of Lammas, and of the same Goodness; but it gives a little yellow Cast to the Bread.
Another Sort of lodging Blight there is, which some call Moar-Loore, and mostly happens on light Land. This is when the Earth, sinking away from the Roots, leaves the Bottom of the Stalk higher than the subsided Ground; and then the Plant, having only these naked Roots to support it (for which they are too weak), falls down to the Earth.
To remedy this, turn a shallow Furrow against the Rows, when they are strong enough to bear it, and when the Mould is very fine and dry; then the Motion of the Stalks by the Wind will cause such Earth to run through the Rows, and settle about the Roots, and cover them[160].
[160]Some Land is very subject to the Misfortune of exposing the Roots, and therefore is less proper for Wheat; for when the Roots are left bare to the Air, they will be shrivelled, and unable to support the Plants: And on such Land the Wheat plants have all fallen down, though in Number and Bigness not sufficient to have produced the Fourth Part of a tolerable Crop, if they had stood. I am inclined to believe, that a thorough Tillage might be a Remedy to such a loose hollow Soil; for ’tis certain to a Demonstration, that it would render it more dense, and increase its specific Gravity: But to enrich it sufficiently without Manure, the Tillage must pulverize it much more minutely, and expose it longer, than is required for the strongest Land: The Fold also will be very helpful on such hollow Land.
I have never seen any drill’d Wheat so much spoil’d by falling, as sewn Wheat sometimes is. The drill’d never falls so close to the Ground, but that the Air enters into Hollows that are under it, and the Wind keeps the Ears in Motion. Notwithstanding all the Precaution that can be used, in some unseasonable Years Wheat will be blighted: I have known such a general Blight, when some of my Lammas Wheat, planted late on blighting Land, was blighted, amongst the rest of my Neighbours, by the Insects, but the Grain of the sown Wheat was vastly more injured than that of the drill’d: The former was so light, that the greatest Part was blown away in winnowing, and the Remainder so bad, that it was not fit to make Bread: The drill’d made as good Bread, and had as much Flour in it, as the sown Wheat had, that was not blighted; for the Grains of the drill’d were much larger than those of the sown; being form’d to have been twice as big as the Grains of Wheat generally are, had they not been blighted.