Manual of American Grape-Growing Part 18

Of black grapes, Black Hamburg carries the palm of merit because it is most easily grown, best stands neglect, is a heavy producer, sets its fruit well, the grapes mature early; and, in particular, it meets the requirements of the unskilled gardener better than any other grape.

The cl.u.s.ters are not as large and the flavor not as good as that of some other sorts.

Muscat of Alexandria is the best of the white varieties. It is, however, a hard grape to handle since it requires a high temperature to bring it to perfection, is a little shy in setting fruit and the grapes are not very certain in coming to maturity; it also requires a long season. A good quality is that it may be kept long after cutting, much longer than Black Hamburg.

For an earlier white grape, Buckland Sweet.w.a.ter has much to recommend it; it ripens from two to three weeks earlier than Muscat of Alexandria and is much more easily grown. It is good in quality but not of high quality. Buckland Sweet.w.a.ter may be well grown in the house with Black Hamburg, whereas it is almost impossible to grow Muscat of Alexandria in the same house with Black Hamburg.

Muscat Hamburg is a cross between Black Hamburg and Muscat of Alexandria, and is an intermediate in most fruit characters between these two standard sorts. It is not, however, very generally grown, although it well deserves to be because of its large, beautiful, tapering cl.u.s.ters of black grapes of finest quality.

Grizzly Frontignan adds novelty to luxury in the list of indoor grapes. The fruits are mottled pink in color, deepening sometimes to a dark shade of pink, and are borne in long, slender cl.u.s.ters. The grapes ripen early and are unsurpa.s.sed in quality but are, all in all, rather difficult to grow.

Barbarossa and Gros Colman are the two best late black grapes, especially for those who are ambitious to grow cl.u.s.ters of large size with large berries. Both are very good in quality. Neither of the two is particularly easy to grow, since they require a long time to ripen; but, to offset this, both keep longer than any other sorts after ripening. Because of the large size of the berries, thinning must begin early and must be rather more severe than with other grapes.

This variety is now largely grown in England for exportation to this country in early spring.

White Nice and Syrian are two white sorts which attain largest size in cl.u.s.ters, specimens weighing thirty pounds being not infrequent, but are coa.r.s.e and poor in quality and are, therefore, hardly worth growing.

Alicante is a black sort often grown for the sake of variety, since it departs from the Vinifera type rather markedly in flavor. The grapes have very thick skins and may be kept longer than those of any other variety.

Lady Downs is another late-keeping black grape of highest quality, but difficult to grow. The bunches and berries are small in comparison with other standard sorts, characters that do not commend the variety to most gardeners.

Perhaps a dozen more sorts might be named worthy of trial in American graperies, but the list given covers the needs of commercial establishments and will meet the wants of most amateur growers.

PLANTING AND TRAINING

Two-year-old vines are most commonly planted. The vines are set inside the house at least a foot from the walls and four feet apart. The grapery must be built on piers with s.p.a.ces of at least two feet between, and the vines are placed opposite these openings in the foundation. When planted, the vines are cut back to two or three buds, and when these start the strongest are selected for training, the others being rubbed off. The grapery must be strung with wires running lengthwise of the house at about fifteen inches from the gla.s.s. Greenhouse supply merchants furnish at a low price cast iron brackets to be fastened to the rafters to hold these wires. As the growing vines reach one wire after another, they are tied with raffia to hold them in place. Usually, young vines will reach the peak of the house by midsummer, and as soon as this goal is attained must be pinched so that the cane may thicken up and store food in the lateral buds for the coming season. When the wood is well matured, the vine is cut back to half or one-third its length, depending on the variety, laid on the ground and covered for the winter. An item of no small importance in winter care is to keep out mice, this pest being inordinately fond of grape buds, and once the buds are destroyed the vines are ruined for the coming season.

The second year's work is largely a repet.i.tion of that of the first.

The vines are permitted to reach the peak of the house and are again stopped by pinching. A considerable number of laterals spring up on each side of the main vine, and these must be thinned as they develop to stand at the distance apart of the wires to which they are fastened. This is pre-supposing that the gardener has chosen the spur method of pruning, the method generally used in America and the one, all things considered, which gives best results. The selection of the laterals the second year, therefore, is a matter of much importance since spurs are to be developed from them. Care should be taken to have these spurs regularly distributed over the length of the vine.

This second year, grapes must not be permitted to develop on the terminal shoots, but a few cl.u.s.ters may be taken from the laterals in which case the laterals are pinched two buds beyond the cl.u.s.ter, the pinching continuing throughout the season if the laterals persist in breaking, as they will do in most cases. At the end of the season, the terminal is shortened at least one-half, and the laterals are pinched back to a bud as close as possible to the main stem. The vines are then put down for the winter as at the close of the first season.

The work of the third season is a repet.i.tion of that of the second, with the exception that the vine is permitted to fruit throughout its whole length, although not more than one pound of fruit to a foot of main vine is permitted. The plants are now established and the only pruning in this and succeeding years is to cut the laterals at the close of each season close to the main stem, leaving strong healthy buds of which at least one, usually more, will be found close to the stem. If more than one bud starts, only the strongest is chosen, although often an extra one is needed to fill a vacancy on the opposite side. After the third or fourth season, depending somewhat on the variety, two pounds of fruit or more to the foot of the main stem can be permitted. The novice, however, is likely to permit his vines to overbear with the result that the crop is cast, or the berries rattle, or the fruit turns sour before ripening. From the beginning to the finish of the season, in this method of pruning, much pinching of laterals is required. No hard and fast rule can be laid down for this pinching, but, roughly speaking, all new growth beyond the second joint from the cl.u.s.ter should be pinched out as fast as it shows. With most varieties, this means that the lateral is kept about eighteen inches from the main stem. After a few years, well-developed spurs form at the base of the original laterals, and from these spurs the new wood comes year after year.

An alternative method of pruning is to permit the new canes to grow up from a bud near the ground each season. When the vine is well established, this new cane is fruited throughout its entire length, the laterals being pinched as described under the spur method. This method of pruning is known as "the long cane method." Gardeners hold that they can grow better fruit with this than with the spur method, but the difficulties are greater and the crop is not as large.

CARE OF THE VINES

With the cultivation of all varieties indoors, more cl.u.s.ters set than the vines can carry. This means that a part of the cl.u.s.ters must be removed, an operation that depends on the variety and one that requires experience and judgment on the part of the gardener. Roughly speaking, half the cl.u.s.ters are taken, leaving the other half as evenly distributed on each side of the vine as possible. The time to take these cl.u.s.ters is also a delicate matter, since some sorts are shy in setting and the cl.u.s.ters must not be taken until the berries are formed and it can be seen how large the crop will be. As a rule, however, this thinning of cl.u.s.ters may be begun as soon as the form of the cl.u.s.ter can be seen.

It is very necessary also, especially with all sorts bearing large berries, that grapes be thinned in the cl.u.s.ter. The time to thin the cl.u.s.ter varies with the variety. Sorts which set fruit freely can be thinned sooner than those which are shy in setting. On the one hand, the thinning must not be done too soon as it cannot be told until the berries are of fair size which have set seed and which have not; however, if thinning is neglected too long, the berries become over-crowded and the task becomes difficult. The thinning is performed with slender scissors, and the bunches must not be touched with the hand, as touching impairs the bloom and disfigures the fruit. The cl.u.s.ters are turned and steadied by a small piece of pencil-shaped wood. Thinning is practiced not only to permit the berries to attain their full size but also to permit the bunches to attain as great size as possible. If too severely thinned, the cl.u.s.ters flatten out after maturity. This is especially the case when too many berries are taken from the center of the bunch. A large cl.u.s.ter of grapes is made up of several small cl.u.s.ters, making it necessary to tie up the upper cl.u.s.ters or shoulders of the bunch to permit the berries to swell without being thinned too severely. Grapes intended for long keeping require more thinning than those to be used at once after picking, since, in keeping, the berries mold or damp-off in the center of the bunch if it is too compact.

The vines in the grapery must be watered with considerable care. The amount of water to be used depends on the composition of the borders and the season of growth. If the border is loose and well-drained, the supply of water must be large; if close and retentive, but a small amount of moisture is required. Watering must not be done during the period of blossoming, since dry air is necessary for proper pollination. When the grapes begin to show color, the vines are heavily watered, after which little if any water is applied. Some gardeners mulch the vines with hay to retain the moisture in the house and keep the atmosphere dry.

Ventilating the grapery is another important detail of the season's work. Proper ventilation is difficult to secure in the early spring months when the dryness of the sun on the one hand, and cold air on the other, make it difficult to avoid draughts and regulate the temperature. Another troublesome time is when the grapes begin to color, as it is then necessary for the grapery to have air at night; but when too much air enters, there is danger from mildew. Towards the end of the season, all parts of the plant become harder in texture and the grapery may then be more generously aired. After the fruit is cut, the houses are ventilated in full so that the wood may ripen properly.

PESTS

Several pests vex the gardener in growing grapes indoors. Of these, mealy-bug, red-spider, thrips and mildew are most troublesome. In a well-conducted grapery, there is never an intermission in the warfare against these pests.

Mealy-bug is usually a sign of sloth on the part of the gardener. In a grapery devoted exclusively to grape-growing, it should never be seen, but, since gardeners must often grow other plants in the grapery, mealy-bug sooner or later appears and is often hard to dislodge. It is best repelled by removing the loose bark on the trunks which harbor the pest and then was.h.i.+ng with kerosene emulsion. When this becomes necessary, not only the vines but the rafters and all parts of the house should be sprayed with the emulsion.

Red-spider is another pest usually found in the grapery, but it thrives only in a dry atmosphere and is easily gotten rid of by syringing. As soon as red-spider appears in a house its appearance is usually known by the reddish tinge on the foliage; syringing should be kept up until the pest is disposed of, keeping the house damp in all except dull weather. Syringing is done only when plenty of air can be given and when it can be followed by sunlight so that the water remains on the vines as short a time as possible.

Thrips, another small insect, is sometimes troublesome but not often and is now easily controlled by applications of nicotine. Much care must be taken in the application of nicotine late in the season, otherwise the fruit will be injured.

The only fungous disease of the grape troublesome in the greenhouse is mildew. Mildew is usually brought on by a sudden change of temperature or by draughts in the grapery. Gardeners are of the opinion that east winds, in particular, give unfavorable conditions for mildew and prefer to open the ventilators to the west. If taken in time, mildew is easily kept in check by preventing the conditions which favor it, and by dusting the vines in dry suns.h.i.+ne with sulfur.

[Ill.u.s.tration: PLATE XVI.--Elvira (2/3).]

CHAPTER XII

GRAPE PESTS AND THEIR CONTROL

In common with other cultivated fruits, grapes are at the mercy of numerous insect and fungous pests unless man intervenes with remedial or preventive treatment. Happily for viticulture, knowledge of the pests of the vine has made such advancement in recent years that practically all are now controlled by remedial or preventive measures.

Possibly no field of agriculture has had greater need, or received greater aid from science in the study and control of insects and diseases than grape-growing. A separate treatise would be required to treat the pathological troubles of the grape fully; only such details of the life histories of the several pests to be discussed as are essential to a proper understanding of the control of the parasites can be given here.

INSECT PESTS

Insects troubling the grapes are numerous, at least 200 having been described in America, most of which have their habitat on the wild prototypes of the cultivated vines of this continent. For this reason, with a few exceptions, the insect pests of the grape in America are widely distributed, abundant, and, therefore, often very destructive to vineyards unless vigorously combated. The many pestiferous species vary greatly in importance, depending on locality, weather and the variety. Phylloxera, however, the country over, is most common and deserves first attention.

_Phylloxera._

This minute sucking insect (_Phylloxera vastatrix_), injures the grape by feeding on its roots. Decay usually follows its work on the roots and is often more injurious than the harm done directly by the parasite. This decay is always much more serious on European vines than on those of our native species. The phylloxera is a native of the United States east of the Rocky Mountains, from whence it was introduced into France and from France into California, where it causes much greater damage than elsewhere in the United States.

Wherever the pest is found, it is more injurious in heavy than in sandy soils. In fact, in very sandy soils the vines are often sufficiently resistant to be practically immune.

[Ill.u.s.tration: FIG. 36. Leaf-galls of the phylloxera.]

The life history of the phylloxera is very complex where the different forms of the insect appear and need not be entered into in detail here. East of the Rockies, the most evident indication of the presence of the pest is great numbers of leaf-galls on the under side of the leaves of the grape as shown in Fig. 36. These galls, however, are seldom to be seen in California and are not present on Concords and some other varieties in the East. The winter egg may be taken as the beginning of the life cycle of the phylloxera. From a single winter egg a colony may arise, the first insect after hatching making its way to the leaves where it becomes a gall-maker and gives rise to a new generation of egg-laying root-feeders. On varieties and in regions where the gall form is not found, the insect probably goes directly from the winter egg to the roots. Once the pest is established on the roots, generation follows generation throughout the growing period of the vines, as many as seven or eight occurring in one season.

From midsummer until the close of the growing season, some of the eggs deposited by the root-feeders develop into nymphs which acquire wings and emerge from the soil to form new colonies from eggs deposited on the under side of the leaf. An individual insect deposits from three to six eggs of two sizes, from the larger of which come the females and these, after fertilization, move to the rough bark of the vine and deposit the winter egg for the renewal of the cycle.

Several methods of control have been employed in Europe and California, as treatment by carbon bisulfide injected in the soil; flooding in vineyards that can be irrigated; confining the vines to sandy soils; and, most important, planting vines grafted on resistant stocks, there being great variation in immunity of species of American grapes to phylloxera. The subject of stocks resistant to this pest has been discussed in Chapter IV and need not be taken up again. East of the Rockies, treatment is not necessary with American grapes.

_The grape root-worm._

The grape root-worm is the most harmful of the insect pests of grapes in the grape-belt along the sh.o.r.es of Lake Erie in Ohio, Pennsylvania and New York. This root-worm (Fig. 37) is the larva of a grayish-brown beetle (_Fidia viticida_), shown in Fig. 38. The worms feed at first on the rootlets and later on the bark of the larger roots of the vines so that the injured plants show roots devoid of rootlets and bark channeled by the pest. So plain is the work of the root-worm that the grower never need be at a loss as to the cause of vines injured by this pest. The worms feed during the latter part of the growing season, reaching full growth at this time. The next June they transform into pupae and in late June or early July emerge as adult beetles.

[Ill.u.s.tration: FIG. 37. The grape root-worm.]

[Ill.u.s.tration: FIG. 38. Root-worm beetle.]

The presence of the adult beetles is more easily detected on the foliage than is that of the larvae on the roots, for the feeding beetles ravenously devour the upper sides of the leaves, leaving chain-like markings, shown in Fig. 39, their destructiveness decreasing somewhat after a few days from their first appearance. A fortnight after the beetles begin their attack on the foliage the female begins laying her eggs, to the number of 200, placing them under the rough bark of trunk and cane. These hatch in late July or August and the young grubs at once seek the roots.