Manual of American Grape-Growing Part 9

"The general plan of the tests was much like that at Fredonia in most of the vineyards, with the additions of plats for stable manure and for leguminous and non-leguminous cover crops with and without lime.

From two to six check plats were left for comparison in each vineyard.

As already stated the results were often inconsistent in duplicate plats in the same vineyard, and if one test appeared to point definitely in a certain direction, the indication would be negatived by results in other vineyards. In these experiments the yield of fruit was the only index to the effect of treatments as it was not possible to weigh leaves or pruned wood, or to count the canes left.

"Nitrogen and pota.s.sium in combination, which gave the largest gains and greatest profit in the Station vineyard at Fredonia, showed a 13 per ct. increase in yield on one plat in the Jennings vineyard and a 9 per ct. decrease on the other; in the Miner vineyard this combination apparently resulted in a 25 per ct. increase; in the Lee vineyard in a 2-1/2 per ct. loss; in the Hamilton vineyard a 17 per ct. gain; and in the Grandin vineyard neither gain nor loss. In only two of the five vineyards in which this combination was tested was the gain great enough to pay the cost of the fertilizer applied. Similar discrepancies, or absence of profitable gain, mark the use of the other fertilizer combinations.

"Even stable manure, the standby of the farmer and fruit-grower, when applied at the rate of five tons per acre each spring, and plowed in, did not, on the average, pay for itself. Indeed, there were few instances among the 60 comparisons possible, in which more than a very moderate profit could be credited to manure. The average increase in yield following the application of manure alone was less than a quarter of a ton of grapes to the acre; while the use of lime with the manure increased the gain to one-third of a ton per acre. The ton of lime to the acre annually would not be paid for by the gain of 175 pounds of grapes. Cover-crops were used in five of the six cooperative experiments and proved even less adapted to increasing crop yields than did the manure. There was no appreciable gain, on the average, from the use of mammoth clover; indeed, a slight loss must be recorded for the clover except upon the plats which were also limed, and even with the lime the average yields on check plats and mammoth clover plats differed by only one one-hundredth of a ton. Wheat or barley with cow-horn turnips made a slightly better showing, as the plats on which these crops were turned under, without lime, averaged about one-twentieth of a ton to the acre better than the checks. With these non-legumes, lime was apparently a detriment, as the plants with the lime yielded a tenth of a ton less, on the average, than those without it."

_Practical lessons from the Fredonia experiment._

From this experiment it becomes clear that the use of fertilizers in a vineyard is a local problem. General advice is of little value. It is evident also that the fertilization of vineyards is so involved with other factors that only carefully planned and long continued work will give reliable information as to the needs of vines. Indeed, field experiments even in carefully selected vineyards, as the cooperative experiments show, may be so contradictory and misleading as to be worse than useless, if deductions are made from the results of a few seasons. The experiment, however, has brought forth information about fertilizing vineyards that ought to be most helpful to grape-growers.

Thus, the results suggest:

_Only vineyards in good condition respond to fertilizers._

It is usually waste to make applications of fertilizers in poorly drained vineyards, in such as suffer from winter cold or spring frosts, where insect pests are epidemic and uncontrolled or where good care is lacking. The experiments furnish several examples of inertness, ineffectiveness or failure to produce profit when the fertilizers were applied under any of the conditions named. They emphasize the importance of paying attention to all of the factors on which plant growth is dependent. Moisture, soil temperature, aeration, the texture of the soil, freedom from pests, cold and frosts, as well as the supply of food may limit the yield of grapes.

_A vineyard soil may have a one-sided wear._

It is certain in some of the experiments and strongly indicated in others that the soil is having a one-sided wear--that only one or a very few of the elements of fertility are lacking. The element most frequently lacking is nitrogen. Exception will probably be found in very light sands or gravels which are often deficient in potash and the phosphates; or on soils so shallow or of such mechanical texture that the root range of the vine is limited; or in soils so wet or so dry as to limit the root range or prevent biological activities. These exceptions mean, as a rule, that the soils possessing the unfavorable qualities are unfitted for grape-growing. The grape-grower should try to discover which of the fertilizing elements his soil lacks and not waste by using elements not needed.

_Grape soils are often uneven._

The marked unevenness of the soil in the seven vineyards in which these experiments were carried on, as indicated by the crops and the effects of the fertilizers, furnishes food for thought to grape-growers. Maximum profits cannot be approached in vineyards in which the soil is as uneven as in these, which were in every case selected because there was an appearance of uniformity. A problem before grape-growers is to make uniform all conditions in their vineyards, and the vines must be kept free from pests if fertilizers are to be profitably used.

_How a grape-grower may know when his vines need fertilizers._

A grape-grower may a.s.sume that his vines do not need fertilizers if they are vigorous and making a fair annual growth. When the vineyard is found to be failing in vigor, the first step to be taken is to make sure that the drainage is good; the second step, to control insect and fungous pests; the third, to give tillage and good care; and the fourth step is to apply fertilizers if they be found necessary. Few vineyards will be found to require a complete fertilizer. What the special requirements of a vineyard are can be ascertained only by experiment and are probably not ascertainable by a.n.a.lyses of the soil.

This experiment furnishes suggestions as to how the grape-grower may test the value of fertilizers in his own vineyard.

_Applying fertilizers._

When it is certain that vines need fertilization, and what is wanted is known, the fertilizers should be put on in the spring and be worked in by the spring cultivation. Stable manure should be plowed under.

Grape roots forage throughout the whole top layer of soil so that the land should be covered with the fertilizer, whether chemical or barnyard manure. Applications of commercial fertilizers are generally spread broadcast, though it is better to drill them in if the foliage is out on the vines and thus avoid possible injury to tender foliage.

Commercial fertilizers should be mixed thoroughly and in a finely divided state. In leachy soils, nitrate of soda ought not to be applied too early in the season, as it will quickly wash down out of reach of the grape roots.

[Ill.u.s.tration: PLATE VIII.--Brighton (2/3).]

_Over-rich soils._

Some soils are too rich for the grape. On these the growth is over-luxuriant, the wood does not mature in the autumn, fruit-buds do not form and the fruit is poor in quality. Certain varieties can stand a richer soil than others. Over-richness is a trouble that may cure itself as the vines come in full bearing and make greater demands on the soil for food. It is well, however, on a soil that is suspected of being too rich or so proved by the behavior of the vines, to provide an extra wire on the trellis, to prune little and thus take care of the rampant growth. Some soils, however, and this is often the case, are so rich that the grape cannot be made to thrive in them; the vines waste their substance in riotous living, producing luxuriant foliage and l.u.s.ty wood but little or no fruit.

CHAPTER VII

PRUNING THE GRAPE IN EASTERN AMERICA

The inexperienced look on pruning as a difficult operation in grape-growing. But once a few fundamentals are grasped, grape-pruning is not difficult. There is much less perplexity in pruning the grape than in pruning tree-fruits. Pruning follows accepted patterns in every grape region, and when the pattern is learned the difficulties are easily overcome. The inexperienced are confused by the array of "principles," "types," "methods," "systems" and the many technical terms that enter into discussions of grape-pruning. Some of the technicalities come from European practices, and others originated in the infancy of grape-growing in this country when there was great diversity in pruning. Divested of much that is but jargon, an inexperienced man can easily learn in a few lessons, from word of mouth or printed page, how to prune grapes.

The simplicity of pruning has led to slighting the work in commercial vineyards, by too often trusting it to unskilled hands. Then, too, in this age of power-propelled tools, pride in hand labor has been left behind, and few grape-growers now take time and trouble to become expert in pruning. Simple as the work may seem to those long accustomed to it, he who wants to put into his pruning painstaking intelligence and to taste the joy of a task well done finds in this vineyard operation an ample field for pleasure and for the development of greater profits. The price to be paid by those who would thus attempt perfection in pruning the vine is forward vision, the mechanic's eye, the gardener's touch, patience, and pride in handicraft.

Simple as pruning is, the pruner soon learns that it is an art in which perfection is better known in mind than followed in deed. The theory is easy but there are some stumbling blocks to make its consummation difficult. It is an art in which rules do not suffice, for no two vineyards can be pruned alike in amount or method, and every grape-grower finds his vineyard a proper field for the gratification of his taste in pruning. Happily, however, enlightened theory and sound practice are in perfect accord in grape-pruning, so that specific advice is well founded on governing principles.

One cannot, of course, learn to prune unless he understands the habit of the grape-vine and is familiar with the terms applied to the different parts of the vine. As a preliminary to this chapter, therefore, knowledge of Chapter XVII, in which the structure of the grape-vine is discussed, is necessary. The next step is to distinguish between pruning and training.

PRUNING AND TRAINING DISTINGUISHED

The grape is pruned to increase in various ways the economic value of the plant by increasing the quant.i.ty and value of the crop. This is pruning proper. Or grapes are pruned to make well-proportioned plants with the parts so disposed that the vines are to the highest degree manageable in the vineyard. This is training. To repeat, the grape-plant is pruned to regulate the crop; it is trained to regulate the vine. Grape-growers usually speak of both operations as "pruning,"

but it is better to keep in mind the two conceptions. The distinctions between pruning and training must be made more apparent by setting forth in greater detail the results attained by the two operations.

_Results attained in pruning to regulate the crop._

Proper pruning of vines in their first year in the vineyard, which, as we have seen, consists of cutting the young plants back severely, brings the vines in productive bearing a year or two years earlier than they would have borne had the pruning been neglected. This early pruning, since it is done with an eye to the vigor of each vine, insures greater uniformity in the growth and productiveness of the vineyard. Uniformity thus brought about is important not only for the time being, but for the future development of the vines, since weak vines, if unpruned, are stunted and may require years to overtake more vigorous vines in the vineyard.

The quality of the crop may be regulated by pruning. When vines bear too heavily, the grapes are small, and wine-makers have found that they seldom develop sugar and flavor as do grapes on vines not over-bearing. Grapes on vines too heavily laden seldom ripen or color well. Not only are the grapes on poorly pruned and unpruned vines poor in quality but the grapes on such vines are usually not well distributed and therefore ripen and color unevenly. The results just mentioned follow because the bunches in a poorly distributed crop receive varying amounts of light and heat depending on the distance from the ground, the distance from the trunk and on the amount of shade.

Pruning may be used to regulate the quant.i.ty of grapes borne in a vineyard and so be made somewhat helpful in preventing alternate bearing. Abnormally large crops are usually followed by partial crop failure and biennial bearing sometimes sets in, but the large crop may be reduced by pruning and the evil consequences wholly or partly avoided. It follows that pruning must depend much on the vigor of the vine; for a weak vine may be so pruned as to cause it to overbear; and, on the other hand, a vigorous vine pruned in the same way might not bear at all.

_Results attained in pruning to regulate the vine._

It is necessary to regulate the shape of the vine by training so that tilling, spraying, pruning and harvesting can be easily performed and the crop be kept off the ground. The cost of production is always less in a well-pruned vineyard because all vineyard operations are more easily carried out.

The life of a vineyard is lengthened when the vines are well trained, because when the parts of a vine are properly disposed on trellis or stake the plants are less often injured in vineyard operations.

Moreover, not infrequently vines die from over-production and consequent breaking of canes or trunks which might have been prevented by pruning to shape the vine. Suckers and water-sprouts are less common on well-trained vines. It is necessary, too, by training to keep the bunches away from trunk, canes and other bunches and so prevent injury to the grapes.

Lastly, fashion, taste or a more or less abnormal use of the grapes, may prescribe the form in which a vine is trained. Fashion and taste run from very simple or natural styles to exceedingly complex, formal ones, depending, often, on the variety, the environment or other condition, but just as often on the whim of the grape-grower. The grape is a favorite ornamental for fences, arbors and to cover buildings; for all of these purposes the vines must be trained as occasion calls.

SOME PRINCIPLES OF PRUNING

Leaving the shaping of the plant out of consideration and having in mind pruning proper, all efforts in pruning are directed toward two objects: (1) The production of leafy shoots to increase the vigor of the plant. (2) The promotion of the formation of fruit-buds. The first, in common parlance, is pruning for wood; the second, pruning for fruit.

_Pruning for wood._

Some grapes, in common with varieties of all fruits, produce excessive crops of fruit so that the plants exhaust themselves, to their permanent injury and to the detriment of the crop. Something must be done to restore and increase vegetative vigor. The most natural procedure is to lessen the struggle for existence among the parts of the plant. The richer and the more abundant the supply of the food solution, the greater the vegetative activity, the larger the leaves and the larger and stouter the internodes. Obviously, the supply of food solution for each bud may be increased by decreasing the number of buds. The weaker the plants, therefore, the more the vine should be cut. The severe pruning in the first two years of the vine's existence is an example of pruning for wood. The vine is pruned for wood in the resting period between the fall of leaf and the swelling of buds the following spring.

_Pruning for fruit._

Growers of all fruits soon learn that excessive vegetative vigor is not usually accompanied by fruitfulness. Too great vigor is indicated by long, leafy, unbranching shoots. Some fruit-growers go so far as to say that fruitfulness is inversely proportionate to vegetative vigor.

There are several methods of diminishing the vigor of the vine; as, withholding water and fertilizers, stopping tillage, the method of training and by pruning. Pruning is used to decrease the vigor of the vine, in theory at least, for the practice is not always so successful, by pruning the roots or by summer-pruning the shoots.

Root-pruning the grape at intervals of several years is a regular practice with some varieties in warm countries, Europe more especially, but is seldom or never practiced in America except when planting and when roots arise from the cion above the union of stock and cion.

Summer-pruning to induce fruitfulness consists in removing new shoots with newly developed leaves. These young shoots have been developed from reserve material stored up the preceding season, and until they are so far developed that they can perform the functions of leaves they are to be counted as parasites. When, therefore, these shoots are pruned or pinched away, the plant is robbed of the material used by the l.u.s.ty shoot which up to this time has given nothing in return. The vigor of the plant is thus checked and fruitfulness increased.

Summer-pruning may become harmful if delayed too long. The time to prune is past with the grape when the leaves have pa.s.sed from the light green color of new growth to the dark green of mature leaves.