Manual of American Grape-Growing. U. P. Hedrick
rye and buckwheat. Combinations of these usually make the seed too costly or the trouble of sowing too great. Yet some combinations of a leguminous and non-leguminous crop would seem to make the best green crop for the grape. Thus, a bushel of oats or barley plus ten pounds of clover or twenty pounds of winter vetch, a combination often used in orchards, should prove satisfactory in the vineyard. Or, doubling the amount of seed for each, these crops could be alternated, with a change in the rotation every four or six years, with cow-horn turnip or rape. Turnip and rape require at least three pounds of seed to the acre.
The cover-crop is sown in midsummer, about the first of August in northern latitudes, and should be plowed under in the fall or early spring. Under no circumstances should the green crop be permitted to stand in the vineyard late in the spring to rob the vines of food and moisture. The weather map must be watched at sowing time to make sure of a moist seed-bed. Plate III illustrates two vineyards with well-grown cover-crops.
Tillage
Grape-growers are not in the fog that befuddles growers of tree-fruits in regard to tillage. He is a sloven, indeed, who permits his vines to stand a season in unbroken ground, and there are no growers who recommend sod or any of the modified sod-mulches for the grape. Tillage is difficult in hilly regions and the operation is often neglected in hillside vineyards, as in the Central Lakes region of New York, but even here some sort of tillage is universal. The skip of a single season in tilling stunts the vines, and two or three skips in successive seasons ruin a vineyard. No one complains that grapes suffer from over-tilling as one frequently hears of tree-fruits. There is no tonic for the grape that compares with cultivation when the leaves lack color and hang limp and the vine has an indefinable air of depression; and there is nothing better than cultivation to rouse latent vigor in a scorching summer, or when drought lays heavy on the land.
Tillage tools.
The tools to be used in tilling grapes vary with the topography of the vineyard, the kind of soil and the preferences of the vineyardist. The best tool is the one with which the ground can be well fitted at least expense. Good work in the vineyard requires at least two plows, a single-horse and a two-horse plow. The latter, except on very hilly land, should be a gang-plow. For commercial vineyards of any considerable size, several cultivators are necessary for different seasons and conditions of the soil. Thus, every vineyard should have a spring-tooth and a disc harrow, one of the several types of weeders, a one-horse and a sulky cultivator. If weeds abound, it is necessary to have some cutting tool, or an attachment to one of the cultivators, to slide over the ground and cut off large weeds. Another indispensable tool in a large vineyard is a one-horse grape-hoe, to supplement the work of which there must be heavy hand-hoes. Very often the surface soil must be pulverized, and a clod-crusher, roller or a float becomes a necessity. A full complement of bright, sharp tools at the command of the grape-grower goes far toward success in his business.
Tillage methods.
There are several reliable guides indicating when the vineyard needs to be tilled. The vineyardist who is but a casual observer of the relation of vineyard operations to the life events and the welfare of his vines will take the crop of weeds as his guide. It is, of course, necessary to keep down the weeds, but the man who waits until weeds force him to till will make a poor showing in his vineyard. The amount of moisture in the soil is a better guide. The chief function of tillage is to save moisture by checking evaporation and to put the soil in such condition that its water-holding capacity is increased. The physical condition of the land is another guide. Tilling when the soil needs pulverizing furnishes a greater feeding surface for the roots.
Tillage begins with plowing in early spring. Whether provided with a cover-crop to be turned under or hard and bare, the land must be broken each spring with the plow. Plowing is best done by running a single furrow with a one-horse plow up to or away from the vines as occasion calls and then following with a two-horse or a gang-plow. Some growers use a disc harrow instead of the plow to break the land in the spring, but this is a doubtful procedure in most vineyards and is impossible when a heavy green-crop covers the land. Tillage with harrow, cultivator, weeder or roller then proceeds at such intervals as conditions demand, seldom less than once a fortnight, until time to sow the cover-crop in midsummer. About the time grapes blossom, the grape-hoe should be used to level down the furrow turned up to the vines in the spring plowing. Tillage should always follow a heavy rain to prevent the formation of a soil crust, this being a time when he who tills quickly tills twice. The number of times a vineyard should be tilled depends on the soil and the season. Ten times over with the cultivator in one vineyard or season may not be as effective as five times in another vineyard or another season. In some regions, as in New York, the grower is so often at the mercy of wet weather in early spring that the plowing is best done in the fall, and spring operations must then open with harrowing with some tool that will break the land thoroughly.
The depth to till is governed by the nature of the soil and the season. Heavy soils need deep tilling; light soils, shallow tilling; in wet weather, till deeply; in dry weather, lightly. Grape roots are well down in the soil and there is little danger of injuring them in deep tillage. The depth of plowing and cultivating should be varied somewhat from season to season to avoid the formation of a plow-sole. In some regions plowing and cultivating may be made a means of combating insects and fungi, and this regulates the depth of tillage. Thus, in the Chautauqua grape-belt of western New York, the pupa of the root-worm, a scourge of the grape in this region, is thrown out and destroyed by the grape-hoe just as it is about ready to emerge as an adult to lay its eggs on the vines. In all regions, leaves and mummied grapes bearing countless myriads of spores of the mildews, black-rot and other fungi are interned by the plow and cannot scatter disease.
The time in the season to stop tillage depends on the locality, the season and the variety. It is a good rule to cease cultivation a few weeks before the grapes attain full size and begin to color, for by this time they will have weighted down the vines so that fruit and foliage will be in the way of the cultivator. In the North, cultivation ceases in the ordinary season about the first of August, earlier the farther south. Rank-growing sorts, as Concord or Clinton, do not need to be cultivated as late as those of smaller growth and scantier foliage, as Delaware or Diamond. The cover-crop seed is covered the last time over with the cultivator. Plate IV shows a well-tilled vineyard of Concords.
Irrigation
The grape, as a rule, withstands drought very well, several species growing wild on the desert's edge. Even in the semi-arid regions of the far West, where other fruits must always be irrigated, the grape often grows well without artificial watering. Irrigation is practiced in vineyards in the United States only on the Pacific slope and here the practice is not as general as with other fruit crops. Whether the grape shall be grown under irrigation or not is a local and often an individual question answered with regard to several conditions; as the local rainfall, the depth and character of the soil, the cost of water and ease of irrigation. These conditions are all correlated and make about the most complex and difficult problem the growers of grapes in semi-arid regions have to solve. As long, however, as the grape-grower can grow fairly vigorous vines and harvest a fairly bountiful crop by natural rainfall, he should not irrigate; for, even though the crop offsets the cost, there are several objections to growing grapes under irrigation. The vines are subject to more diseases and physiological troubles; the fruit is said to lack aroma and flavor; grapes grown on irrigated land do not stand shipment well, the unduly inflated grapes often bursting; wine-makers do not like irrigated grapes as well as those from non-irrigated lands; and watery grapes from irrigated lands make inferior raisins. It is maintained, however, with a show of reason, that grapes suffer in irrigated vineyards in the ways set forth only when the vines are over-or improperly irrigated.
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