Key Techniques for Fertilizer and Water Management of Grapes in the High-Temperature Season
Summer is an important period for the vegetative growth of the grapevine and the growth and ripening of the fruit. This stage coincides with the tree's nutrient transition, a time when the vine's shoots, leaves, flowers, fruit and roots all grow rapidly, so when planting grapes, attention should be paid to fertilizer and water management in the high-temperature season.
I. Fertilizer and Water Management of Grapes in the High-Temperature Season
1. Fertilizer Section
(1) Pre-flowering stage: 10 days before flowering, apply a topdressing of quick-acting nitrogen fertilizer together with a 300-fold dilution of Sea Elf biostimulant root-application type, to boost the tree's nutrition and promote grape flowering. 7 days before flowering, spray the foliage once with a 1000-fold dilution of Boron Source Library plus an 800-fold dilution of Sea Elf biostimulant foliar type, to increase the fruit-setting rate.
(2) Flowering stage: spray once each at the flowering stage and after flower drop with an 800-fold dilution of Sea Elf biostimulant foliar type plus a 1000-fold dilution of Boron Source Library, to further stabilize fruit set.
(3) Fruit-swelling stage: after fruit set, apply a fruit-swelling fertilizer as a topdressing, 10 jin of potassium nitrate calcium per mu together with a 300-fold dilution of Sea Elf biostimulant root-application type, applied in a ring-shaped trench dug about 1 m from the plant, to enhance nutrition, protect the fruit and strengthen the roots.
(4) Veraison stage: apply about 100 g of potassium sulfate fertilizer per plant, together with a drench of Sea Elf biostimulant; during the grape ripening period, spray the foliage once every 7~10 days with an 800-fold dilution of Phosphorus-Potassium Source Library, to promote fruit coloring, prevent fruit cracking and increase the sugar content of the fruit.
2. Water Section
Irrigate once 1 week before flowering. From the flowering stage to the fruit-setting stage, irrigation is prohibited to prevent flower and fruit drop. During the berry coloring stage, generally do not water. After harvest, irrigate thoroughly once together with the application of base fertilizer. Water promptly after fertilizing.
3. Soil Section
For varieties prone to fruit cracking, use measures such as ground mulching with film or straw as much as possible to maintain a balanced supply of soil moisture.
After irrigation or rainfall, cultivate and weed promptly to keep the soil loose and airy, promote microbial activity, increase the accumulation of available nutrients and reduce the occurrence of pests and diseases.
The depth of cultivation and weeding is about 10 cm, to prevent damaging the roots by going too deep.
II. Pruning of Grapes in the High-Temperature Season
Summer pruning of grapevines is a supplement to winter pruning and is carried out during the vigorous growth period from May to August, generally requiring 4~5 prunings. Its purpose is to regulate the conflict between growth and fruiting, control apical dominance, reduce ineffective consumption, improve the ventilation and light environment, and promote fruit development and flower bud differentiation.
1. Bud rubbing
Grapevines sprout many buds in early spring, and some nodes send out double shoots; rubbing off excess buds can save the tree's nutrients.
When the sprouts are 1~2 cm long, remove the basal sprouts below 50 cm from the ground, and rub off weak buds, diseased and pest-damaged buds, overly dense buds, etc. Where 2~3 buds sprout at one node, keep 1 bud; keep the main bud and remove the secondary bud; keep vigorous buds and remove weak ones.
2. Pinching
Pinching is generally carried out from 3~5 days before flowering to the beginning of flowering. The pinching point should preferably be 2~3 tender leaves below the growing point, and it should not be too light or too heavy.
(1) Vegetative shoots: pinch leaving 16~20 leaves; reserve shoots leave 9~13 leaves for pinching; when growth is excessively vigorous, pinch several times to control their growth.
(2) Fruiting shoots: the timing of pinching depends on tree vigor, variety and flower-drop characteristics; generally pinch leaving 5~7 leaves above the inflorescence. For varieties with heavy flower and fruit drop, pinching should be early, generally carried out 4~5 days before flowering, and at the same time the intensity should be greater, leaving 4~5 leaves above the inflorescence or even leaving only 1~2 leaves when pinching. For varieties with a high fruit-setting rate, pinch at the flowering stage or after heavy flower drop, and the pinching intensity is relatively lighter