Technology for repairing young and fruiting vineyards

When establishing vineyards, some plants usually fail to take root, and among those that do, some turn out to be a cultivar mixture. Given this, effective measures are taken in the very first year of vineyard establishment to repair young plantations — filling in empty spots and eliminating the cultivar mixture.

The most common causes of plant losses include:

• Low quality of planting material: weak development of the root system of nursery plants and their aerial part, poor graft union in grafted nursery plants, and damage by low temperatures during storage and transportation.
• Poor-quality planting: unsatisfactory soil preparation, lack of contact between the root system of the nursery plant and the soil, or planting the vineyard in dry or waterlogged soil.
• Poor care for young plantations: lack of or delayed irrigation in irrigated viticulture zones, poor covering of bushes for the winter in regions with cover culture, and poor-quality weed control, soil tillage, or vine management.
• Damage caused to bushes during mechanized cultivation of rows and inter-rows.

Plant losses are eliminated in various ways. In young vineyards, aged 1–2 years, replanting of nursery plants is carried out.

In vineyards older than three years, attempts to fill empty spots by replanting usually end in failure, as young plants are severely suppressed by adult bushes: they are shaded and suffer from poorer water and nutrient availability. Therefore, in vineyards entering fruiting or already fruiting, it is advisable to fill losses with layers from neighboring bushes.

When carrying out vineyard repair by replanting nursery plants, a reserve fund of nursery plants of the same cultivar used to establish the vineyard is created on-site to address gaps. Nursery plants are replanted at the end of the first year of establishment in autumn or the following spring.

Replanting is carried out using the same technology as for vineyard establishment. A post-hole digger can be used to mechanize the labor-intensive process of digging holes. A mandatory condition for repair is meeting high requirements for planting material. Nursery plants must be true-to-type, well-developed, and in a good physiological state. To better guarantee their survival, individual care (irrigation, soil loosening, bush training) is provided after planting.

When repairing a vineyard using layers, bushes located next to the missing ones are used. A strong shoot is grown toward the location of the missing bush, and at its upper end, a foundation for the future bush is created using lateral shoots (suckers). The length of the shoot must correspond to the distance between bushes in the row adopted for the given site.

Typically, layers are laid in a specially dug trench. In regions with grafted crops, air or ground layers are used.

The most common method is layering with a lignified vine. It can be used both on own-rooted and grafted vineyards.

In own-rooted vineyards, the rooted layers are separated from the mother bushes 1–2 years after laying. In grafted plantations, the layers are not separated from the mother bushes.

Preparation of the trench for laying the layer:

• trench depth and width — 60 cm;
• the bottom of the trench is loosened;
• fertilizer is applied per bush: 5–6 kg of humus and 150–200 g of superphosphate;
• fertilizers are thoroughly mixed with the soil.

Planting and care:

• the layer is carefully placed at the bottom of the trench;
• the top with the foundation for the future form is led out to the location of the dead bush and tied to a support;
• after filling the trench with soil and compacting it, irrigation is carried out;
• if layering is performed in autumn in a region requiring winter cover, the shoot is covered with a mound of soil.

With good care, the layers begin to provide a harvest in the second or third year. In areas with a long growing season and high heat availability, thanks to early development and vigorous growth of the bushes, layering is carried out using green shoots, which reach the required length in late June or early July. The technique for performing this operation is the same as that for layering with a lignified shoot.

Air or ground layers are used less frequently. For this purpose, elongated arms of neighboring grapevine bushes are usually used, which are directed away from the existing bush and tied to the lower wire of the trellis.

In viticulture practice, the method of layering an entire bush — katavlak — is used. This method is most acceptable for zones of own-rooted viticulture.

Essence of the method:

1. Only shoots intended for layers (no more than four) are left on the mother bush, while the rest are removed.
2. A hole is dug around the mother bush, the bottom of which should be below the main roots.
3. The underground trunk of the bush is carefully bent along the bottom of the hole and pinned down.
4. For the remaining shoots, trenches are dug toward the missing bushes to a depth of 45–50 cm, in which the layer shoots are placed.
5. Then the shoots are covered with soil, leaving the tips outside at the spots where the losses are to be filled, which are then tied to stakes.

Katavlak can also be used to change the spatial orientation of a vine and for its rejuvenation.

The varietal purity of a vineyard directly determines its productivity. Varietal mixtures and impurities reduce the overall profitability of the plantings, so their identification and replacement begin in the very first year of establishment. To do this, specialists perform field inspections of the leaves, marking mixed vines with tags or paint. In the first 2 years, the varietal mixture is removed by grubbing, planting nursery plants of the main cultivar. On fruiting sites, it is more rational to use the already developed root system and perform top-grafting.

Spring top-grafting: cleft grafting and whip-and-tongue grafting methods

Cleft grafting is performed in early spring, at the moment of active sap flow. This method allows for the rapid replacement of a cultivar and returning the vine to production. After the growth of the scion shoots begins, it is important to timely perform shoot tipping and removal of excess shoots. The vigorous growth of the vine under the influence of a powerful root system is directed towards the accelerated formation of the vine and the initiation of generative organs in the buds.

• Depth of trunk excavation — 30–40 cm
• Depth of rootstock split — 5–6 cm
• Height of the protective mound — 5–6 cm
• Survival rate of cleft grafts — up to 95%

Procedure for performing cleft grafting:

1. The underground trunk of the vine is excavated to a depth of 30–40 cm.
2. A split is made to a depth of 5–6 cm.
3. Two-bud scion cuttings with a slanted cut on the lower part are inserted so that the bud at the base of the cut faces outward.
4. The gap in the trunk between the cuttings is filled with a piece of cane of suitable thickness.
5. The trunk is tightened with twine, the hole is filled with soil, and a protective mound is formed above the top buds using black sand or a mixture of loose soil and sawdust.

In the second year after grafting, the vines produce a full harvest. According to field trial data, the productivity of cultivars is restored very quickly. With timely and high-quality care, the survival rate of cleft grafts reaches 95%.

For the repair of one- to two-year-old rootstock vines in grafted vineyards, whip-and-tongue grafting is applied. One- to two-bud cuttings are used as the scion. Work begins in spring, immediately after the grape "bleeding" ends.

Procedure for performing whip-and-tongue grafting:

1. 5–6 days before grafting, the rootstock is cut off at the soil level or 2–3 cm above it.
2. Grafting is performed using a slanted cut with a tongue.
3. The junction is wrapped with raffia or PVC tape and earthed up with loose, moist soil.

Green grafting and restoration of damaged vines

Green grafting is used on vines where the spring scion did not take, on young rootstocks to eliminate gaps, and on own-rooted vines. With proper care, the survival rate of the method reaches 90–95%. The restoration of vines after severe frost damage to the above-ground part can also be carried out using the underground trunk. If the roots are not damaged, a "black head" cut is applied.

Procedure for performing green grafting:

1. In early spring, before bud break, the vine is cut to a "black head" and earthed up with moist soil.
2. From the emerging sucker shoots, only the required number is left for grafting, and the rest are removed.
3. Wait until both the scion and the rootstock reach a herbaceous (green) state.
4. For the scion shoot, the tip, tendrils, and half of each leaf blade are removed (preserving the side shoots), and its lower end is placed in water.
5. One-bud cuttings are prepared immediately before grafting.
6. Slanted cuts are made at the base of the rootstock shoot at soil level (upon appearance of sap) and on the scion cutting of equal thickness.
7. The components are joined by simple grafting and tightly wrapped with thread or polyethylene film.
8. As the shoots grow, the binding is loosened, the vine is tied to a support, and treated with Bordeaux mixture.

If frosts or spring freezes have destroyed the above-ground part of the vine in own-rooted vineyards, but the trunk and roots are healthy, the vines are restored by cutting to a "black head". New arms and canopy are formed from sucker shoots, which grow back quickly thanks to the preserved powerful root system. This method allows for the complete renewal of the vine with minimal time loss.

• In early spring, a pit 25–30 cm deep and 50–60 cm wide is dug around the vine trunk.
• The head of the vine is sawn off with a hacksaw 5–10 cm below the soil level, followed by smoothing the cut with a sharp knife.
• Then, the pit is filled with loose and moist soil so that a mound 4–5 cm high forms over the trunk cut.
• From the dormant buds located on the underground trunk, sucker shoots develop, from which the necessary vine shape is created.

This method is also used for rejuvenating bushes when their above-ground part needs replacement, while the root system is healthy and functioning well.