Detailed Explanation of Summer Black Grape Cultivation Techniques and Management Methods
First is selection: the north mostly adopts trellis training, while the south mostly adopts single-trunk V-shape or overhead trellis; second is cluster trimming and berry thinning: each fruiting cane on average retains only 1 cluster; third is enlargement treatment, that is, 15 days after flower drop, use 45-50mg/kg gibberellin solution, dip or spray the clusters, and repeat once after 12-15 days; fourth is fruit bagging, and organic fertilizer must be heavily applied; fifth is scientific winter pruning, mainly short-cane pruning, while strong canes may be pruned to medium canes.
1. Trellis selection
The trellis selected varies from place to place. The north mostly adopts trellis training, while the south mostly adopts single-trunk V-shape or overhead trellis. Summer Black grape can use any trellis type. The author advocates trellis cultivation with natural fan-shaped pruning, row spacing 1.7m, plant spacing 0.8m, and 500 plants per 667 sq m. In areas requiring soil burial for cold protection, row spacing can be 2m, plant spacing 0.8m, and 420 plants per 667 sq m. In places with heavy rain, the first wire above ground should be more than 80cm from the ground to prevent rain-splashed mud and sand from contaminating the fruit surface. This trellis type is conducive to fully utilizing land, wind, and light, and is especially conducive to early high yield. Under general management level, the yield per 667 sq m in the second year can reach more than 2000kg.
2. Cluster trimming and berry thinning
Summer Black grape clusters are neat, mostly without shouldered branches, with occasional double clusters. It is recommended that any double clusters have 1 removed. If the cluster is too long, pinch off 1/5-1/4 of the cluster tip 10 days before flowering. Each fruiting cane on average retains only 1 cluster. In actual operation, follow the principle of “strong canes 2, medium canes 1, weak canes none”, that is, vigorous canes at the upper end (front end) of the trellis may retain 2 clusters as appropriate, medium-vigor new shoots retain 1 cluster, and weak canes and training canes retain no clusters. The total number of clusters retained per 667 sq m is about 4000. Summer Black berries are tightly set, so berry thinning is recommended. Manual berry thinning takes too much time, so during full bloom and fruit set, appropriately apply a little water, or combine it with spraying fungicide and consciously spray the clusters to promote moderate flower and fruit drop. Alternatively, during full bloom and fruit set, appropriately shaking or striking the tree can also play a role in flower and fruit thinning.
3. Enlargement treatment
At present, in the domestic grape market, large berries are still favored. Fruit enlargement is conducive to increasing yield and raising commodity value. Summer Black grape grows naturally with small berries; this is a common characteristic of seedless grapes, so enlargement treatment is recommended. That is, 15 days after flower drop, use 45-50mg/kg gibberellin solution, dip or spray the clusters, and repeat once after 12-15 days. Or when the berries are as large as soybean grains, use 45mg/kg gibberellin solution, with every 1-1.5kg mixed with 10ml forchlorfenuron plus Gaoshou (a fruit stem hardening inhibitor) to spray or dip the clusters, once is enough.
4. Fruit bagging
Grape bagging has many benefits: preventing disease, preventing insect pests, preventing bird damage, preventing pollution, ensuring yield, and ensuring quality. The berries produced are not only attractive but also good in taste. It is recommended that whether for field production or greenhouse cultivation, full bagging should be strived for.
5. Water and fertilizer management
As with other grape varieties, it is recommended that in Summer Black grape production, organic fertilizer should be heavily applied. When establishing the planting site, apply 5000kg of organic fertilizer per 667 sq m. After that, every other year, expand outward along one side of the planting trench and apply organic fertilizer once in a trench, applying 4000-5000kg per 667 sq m. In spring, topdress once with quick-acting nitrogen fertilizer to promote budbreak and encourage large clusters. Apply enlargement fertilizer once with a high-nitrogen three-element fertilizer. Topdress once with potassium fertilizer before fruit ripening. The fertilizer amount cannot be generalized and should be determined according to soil fertility, yield, and tree vigor.
6. Scientific winter pruning
Winter pruning is very important and directly relates to the grape yield of the following year. Summer Black grape has good flower bud differentiation, high budbreak rate, and high fruiting cane rate. Therefore, for general tree vigor, mainly short-cane pruning should be used, while strong canes may be pruned to medium canes. For mature vineyards under trellis cultivation with natural fan-shaped pruning, it is recommended to retain 1500-1800 fruiting cane groups per 667 sq m.