What to do about uneven grape berry size? These control measures you need to master

Grape is a widely loved fruit and is widely cultivated, but during its growth it is prone to uneven berry size, which affects economic returns, so what should be done about this situation? What control measures are there? First you need to understand what causes this situation.

1. Causes of uneven grape berry size

1. Uncontrolled fertilizer and water management: too much nitrogen fertilizer applied and too large a water supply.

2. Light plant load: the corresponding yield is not reached and the shoots grow excessively.

3. Only chemical fertilizers are applied while organic fertilizer application is neglected.

4. The timing of shoot tipping and vine bending during the flowering period is too early and too few leaves are retained.

5. During the flowering period the trellis surface is too dense with too many branches, causing poor ventilation and light penetration at the trellis surface during flowering, resulting in flower abortion, a low fruit-setting rate, and loose, scattered clusters.

6. Single or double vines that are too short and a trellis surface that is too low both cause the plant to grow too vigorously, especially in grafted seedlings where it is even more obvious.

2. Control measures

1. Water control: before flowering, if the soil 10 cm below the surface can be formed into a ball when squeezed by hand, it is suitable; generally 2 waterings before flowering, or 1 watering or irrigation for low-lying land or heavy clay soil.

2. Fertilizer control: before flowering apply less nitrogen fertilizer or apply organic fertilizer; when the berries set and grow to the size of a soybean, heavy fertilizer and heavy water are needed; from the pit-hardening stage to the coloring stage, more phosphorus and potassium fertilizer should be applied.

3. Reasonably adjust the plant load: grapevines 4 years and older should all be about 10 kg; during the flowering period, fruiting branches are sufficient; if 20 cm long, retain more than 20 cm; if the thickness is above 1 cm, retain double clusters; especially at the bends of the vertical trellis and on strong shoots at the tips, double clusters or double branches with a single cluster to press the branch should be retained.

4. Reasonable pruning: strong branches (referring to branches above 1.2 cm thick) within 25 cm of a fruiting branch should be thinned out; where the distance between fruiting branches exceeds 20 cm, multi-bud pruning should be adopted to fill empty positions; when bud rubbing and shoot setting are done in the following spring, keep both ends and remove the middle; the branch spacing must be well controlled; when the branch spacing is about 25 cm, retain 3 buds for pruning; in the following spring when rubbing buds and setting shoots, rub out the terminal bud and retain 1-2 buds; strong fruiting branches retain double clusters; when the fruiting branch spacing is 15-20 cm, retain the basal bud for fruiting and rub out the rest; maintain moderate tree vigor.

5. Shoot tipping and vine bending: the time for shoot tipping and vine bending should not be too early; 3-5 days before flowering is suitable; for double-bud fruiting branch groups, when tipping retain long and short shoots; short branches 6-8 leaves, long branches (strong branches) 8-10 leaves; when the cluster is below 10 cm, tip or tip less; at about 20 cm, tip off 1/5.

6. Cutting surface roots: for Kyoho grapevines 4 years and older that have already produced uneven berry size, the surface roots all need to be cut; the method: before vines are taken down in autumn, cut the surface roots cleanly with a shovel; the distance for cutting roots from the base of the plant should not exceed 10 cm, otherwise it will not be effective; after root cutting, spring growth is slightly slower and leaves turn yellow; fertilizer and water management should be strengthened to quickly restore tree vigor.

7. Twisting branches: 3-4 days before flowering, twist and bend or twist flat the upper part of overly strong fruiting branches.

8. Using secondary branches for fruiting: when the grapes are nearly the size of soybeans and uneven berry size is already clearly visible, cut off the upper branches and leaves at 5-6 leaves and use secondary branches for fruiting; this should be done before June 20; it is suitable because it gives a high fruit-setting rate and uniform clusters, but the ripening period is 7-10 days later.

9. Using swelling agents: when uneven berry size is already clearly visible in Kyoho grapes (about 15 days after flowering), dip the clusters once (or spray evenly); the berries will have elasticity; if cracking is found from the coloring stage, water should be controlled in time or drainage should be done after rain.

10. Use of the new tree growth promoter-controller PBO: it has the characteristics of promoting larger grapes, correct color, early ripening, crack prevention, and increased yield; the dosage should be determined according to tree vigor; the first application is 1-2 days before flowering by soil application; for vigorous trees, watering application is suitable at 5-7 grams per plant; for strong trees, apply 2.5-3 grams per plant; for trellis frames, about 250 grams per mu, and for hedge frames 250-500 grams; the second application is about 25 days after flowering by spraying at a concentration of 100-250 times; practice has proved that using PBO on vigorous Kyoho trees significantly increases fruit setting; nitrogen fertilizer should be controlled; in early April apply urea by watering at 100-150 grams per plant; at budding, add urea together with pesticide spraying; in mid-June potassium fertilizer is mainly used as foliar fertilizer; harvesting cannot be interrupted; immediately apply production fertilizer twice and irrigate; from late September to early October, apply more than 3000 kg of farmyard manure and irrigate twice.