What are the precautions for summer pruning of grapes?
Summer weather is hot and the climate is dry, but it is also an important period for the growth and ripening of grape berries. Once managed improperly, it is very easy for them to be attacked by pests. Pruning grapes in summer is one of the common management tasks, so what precautions are there?
1. What precautions are there for summer pruning of grapes?
1. Bud removal and shoot thinning
Bud removal. Removing buds before the young shoots grow to 5 cm is called bud removal. Mainly remove overly dense buds as well as the weak buds among twin buds, so that the remaining new shoots have enough growth space and more nutrient supply. The principle of bud removal is: keep sparse, not dense; keep strong, not weak. During the first bud removal, keep 30% more spare buds to prevent accidental breakage.
Shoot thinning. When the new shoots grow to 10-20 cm and unfold 4-5 leaves, carry out shoot thinning once more. When new shoots on a single trellis are tied vertically, leave one new shoot about every 10-15 cm; for a small trellis, keep about 15-20 new shoots per sq m of trellis surface. When leaving shoots, note that the ratio of fruiting shoots to vegetative shoots should preferably be 2:1.
2. Flower cluster thinning
Flower cluster thinning. Flower cluster thinning can be carried out from when the length of the fruiting shoot reaches 20 cm until just before flowering. According to tree vigor and the strength of the fruiting shoots, thin out excess flower clusters. Generally each fruiting shoot keeps 1 cluster, a few strong shoots may keep 2 clusters, and weak shoots keep no fruit clusters.
Pinching off the flower cluster tip. One week before flowering, pinch off with the fingers 1/4 or 1/5 of the total length of the flower cluster tip. After the number of flower buds on the cluster is reduced, the fruit cluster can be more compact and the berries more uniform in size.
3. Removing tendrils and tying new shoots
Removing tendrils. If grape tendrils are not removed, they will cause inconvenience for later operations such as tying new shoots, harvesting, winter pruning, and taking the vines on and off the trellis, and they also waste nutrients, so tendrils should be removed regularly.
Tying. When new shoots grow to about 40 cm, they need to be tied onto the trellis surface. By changing the direction in which the new shoots extend, adjust the growth vigor of the new shoots. Weak shoots can be tied upright to enhance their growth vigor. New shoots of moderate vigor can be tied at an angle, and overly strong new shoots should be tied as horizontally as possible.
4. Pinching
Pinching means removing about 5-10 cm from the top of the new shoot together with several young leaves. Pinching supplies more nutrients to the flower clusters, thereby increasing the fruit-setting rate and yield.
5. Pruning after harvest
After the grapes are harvested (from the end of May to before mid-June), carry out heavy short-cut pruning of all new shoots back to 1-3 buds to stimulate the winter buds to sprout in the same year, but do not keep fruit clusters; instead, cultivate new branches as fruiting mother branches for the following year. Before pruning, because of the heavy application of post-harvest fertilizer, use Mengli 28 + Hamm Hongyun high-phosphorus water-soluble fertilizer, applied by flushing with water or drip irrigation, which helps restore tree vigor and promote flower bud differentiation for next year. After the winter buds sprout, fertilize as appropriate according to the tree's vigor, spraying Mengli Guolishuang on the leaves once every 15-20 days to enlarge leaf area, leaf thickness and brightness as quickly as possible, promote better photosynthesis, and protect the leaves from pathogen infection.
2. Key points of summer grape management
1. Water management
In late June, as the temperature continues to rise, the berries grow to the size of soybean grains, and the new shoots also grow vigorously. Leaf water evaporation becomes greater and greater, and nutrients and water are urgently needed. Therefore, at this time, combine the application of fruit-promoting fertilizer with irrigation of fruit-promoting water.
2. Timely intertillage
In the later stage of grape growth and development, rainy weather is often encountered. Timely intertillage and weeding can prevent waterlogging and improve the root growth environment, and can promptly eliminate weeds and reduce pest and disease damage. It is better to compost the removed weeds into organic fertilizer. In the rainy season, shallow intertillage should be carried out to a depth of about 5 cm, mainly to eliminate weeds; after the rainy season, carry out deep intertillage. The cultivation depth is 10-15 cm; be careful not to damage the plant roots.
3. Fertilizing after harvest
After the grapes are harvested, the root system enters a new peak growth period. Organic fertilizer should be applied in time as a base fertilizer to help promote new roots and growth the following year. Apply per plant 5-8 kg of Genguo Liangpin organic fertilizer + 2-3 kg of biological bacterial fertilizer + 1-2 kg of compound fertilizer + 0.5-1 kg of medium and trace element microbial agent, applied in a furrow between rows 30 cm from the main trunk, with a furrow depth of 30-40 cm, and irrigate after fertilizing. This gives the grape plants sufficient time to rest and recuperate and lays the foundation for growth and development the following year.