A Detailed Guide to Summer Black Grape Cultivation Techniques and Management Methods

Summer Black grape originated in Japan and is a descendant of Kyoho. It is an early-maturing European-American variety. In Yunnan, Summer Black grapes ripen as early as March, with Summer Black from Quanshan, Yunnan being the main type. Its characteristics are early maturity, seedlessness, high sugar and low acid, rich aroma, fine and crisp flesh, medium firmness, and it is relatively firm among European-American grapes.

Cultivation and Management of Summer Black Grape

1. This variety is early-maturing and high-quality, disease-resistant, high-yielding, and has good storage and transport tolerance. Summer Black is a triploid variety, and its berries are small under natural growth, so gibberellin treatment is needed, which can increase berry size by more than 1 times. Regarding treatment concentration and timing, thorough trials should be carried out in each region to summarize reliable treatment concentrations and methods.

Summer Black matures early and does not drop fruit easily, so it is suitable for forcing cultivation in protected facilities. Trellis choices vary from region to region. The north mostly uses hedge trellises, while the south mostly uses single-trunk V-shaped or overhead trellises. Summer Black grape can use any trellis type.

The author advocates hedge trellis cultivation with natural fan-shaped pruning, row spacing of 1.7 m, plant spacing of 0.8 m, and 500 plants per 667 sq m. In areas requiring soil mounding for cold protection, row spacing can be 2 m, plant spacing 0.8 m, and 420 plants per 667 sq m.

In places with a lot of rain, the distance between the first wire above ground and the ground should be more than 80 cm to prevent rain-splashed mud and sand from contaminating the fruit surface. This trellis type helps make full use of land, wind, and light, and is especially beneficial for early high yield. Under ordinary management, yield per 667 sq m can reach more than 2000 kg in the second year.

2. Cluster trimming and berry thinning Summer Black grape clusters are neat, mostly without shouldered branches, with occasional double clusters. It is recommended that when double clusters occur, one be removed. If a cluster is too long, pinch off 1/5-1/4 of the cluster tip 10 days before flowering.

On average, only 1 cluster is retained per fruiting shoot. In practice, follow the principle of "strong shoots 2, medium shoots 1, weak shoots none": namely, vigorous shoots at the upper end (front end) of the trellis may retain 2 clusters as appropriate, medium-vigor new shoots retain 1 cluster, and weak shoots and training shoots retain no fruit clusters. Retain about 4000 clusters per 667 sq m in total.

Summer Black berries are tightly set, so berry thinning is recommended. Manual thinning is too time-consuming, so during full bloom and fruit set, lightly irrigate with a small amount of water, or when spraying fungicides, deliberately spray the clusters to promote moderate flower and fruit drop. Alternatively, during full bloom and fruit set, moderately shaking or striking the vine can also play a role in flower and fruit thinning.

3. Berry enlargement treatment At present, in the domestic grape market, large berries are still favored. Fruit enlargement helps increase yield and improve commercial value. Summer Black grape grows small berries naturally, which is common to seedless grapes, so enlargement treatment is recommended.

That is, 15 days after flower drop, use a 45-50 mg/kg gibberellin solution to dip or spray the clusters, then repeat once after 12-15 days. Alternatively, when berries are as large as soybean grains, use a 45 mg/kg gibberellin solution, with 10 ml of forchlorfenuron per 1-1.5 kg plus Gaoshou (a stalk-hardening inhibitor), to spray or dip the clusters; one application is sufficient.

4. Fruit bagging Grape bagging has many benefits: it prevents disease, pests, bird damage, and contamination, and protects yield and quality. The berries produced are not only attractive but also taste good. It is recommended that whether for open-field production or greenhouse cultivation, every effort be made to bag all clusters.

5. Water and fertilizer management As with other grape varieties, it is recommended in Summer Black grape production to apply heavy organic fertilizer. When establishing the planting site, apply 5000 kg of organic fertilizer per 667 sq m. After that, every other year, expand outward along one side of the planting trench, open a trench, and apply organic fertilizer once, at 4000-5000 kg per 667 sq m. In spring, apply a quick-acting nitrogen fertilizer once to promote bud break and encourage large clusters.

Apply a high-nitrogen three-element fertilizer once for the enlargement fertilizer. Apply a potassium fertilizer once before fruit ripening. The amount is hard to generalize and should be determined according to soil fertility, yield, and tree vigor.

6. Scientific winter pruning Winter pruning is very important and directly affects the next year's grape yield. Summer Black grape has good flower bud differentiation, a high sprouting rate, and a high fruiting shoot rate. Therefore, for general tree vigor, mainly short-cane pruning should be used, while vigorous shoots can be pruned to medium canes. For mature orchards with hedge trellis cultivation and natural fan-shaped pruning, it is recommended to retain 1500-1800 fruiting shoots per 667 sq m.