How should management work be done well before grape harvest?
Grapes are one of the common fruits in daily life, with a very wide range of varieties. In recent years, the economic benefits of grape cultivation have improved somewhat. Every time the critical period of management before grape harvest arrives, good management can promote nutrient accumulation in the grape vine, enhance stress resistance, and promote fruit coloring, sugar increase, and improved fruit maturity.So what management work should be done well before grape harvest?What problems easily arise when fertilizing after harvest?
1. What management work should be done well before grape harvest?
1. Reasonable leaf retention and yield control
The yield and quality of grapes depend on leaf area. According to research, when the leaf area available to each cluster of grapes is less than 2280 sq cm, the fruit grows slowly. When grape yield per mu is controlled at 1250 kg, each cluster has 25 leaves, the sugar content at maturity reaches 16%-17%, coloring is good, the fruit is elastic and firm, the sugar-acid ratio is moderate, and the flavor is very good.
In management, thinning the fruit so that each new shoot retains one cluster, with cluster weight around 500 grams, ensures that each new shoot retains about 25 leaves under this cluster standard; leave 6 leaves above the flower cluster and top it, and below the top, pinch each lateral shoot after retaining 1 leaf.
During the fruit coloring stage, top the vines by cutting off tender leaves and new shoots that have not yet matured, so that the fruit receives sufficient nutrients, colors evenly, has high sugar content, and suffers fewer diseases.
2. Apply potassium fertilizer during the fruit coloring stage
Grapes are a fruit tree that “likes potassium,” and potassium increases sugar and reduces acid. Fruit quality depends to a large extent on the types and amounts of sugars contained in the fruit. The hard-core softening stage is the peak period for potassium absorption in grapes. During this period, applying 30-40 kg of potassium fertilizer per mu makes grape fruit color quickly, increases sugar content by 2-3 degrees, and gives the fruit high fructose content and a very sweet flavor.
In addition, the root system of grapes begins to decline in the middle and late stages, so fertilization should mainly be water-soluble fertilizer: 100 jin of water + 1.5 kg of potassium sulfate + 10% calcium superphosphate leaching clear liquid. Apply 5 kg of fertilizer solution per plant, once every seven days, for 2-3 consecutive applications.
3. Supplement calcium fertilizer and control water in the later stage
When the nitrogen-to-calcium ratio is 10, calcium deficiency generally does not occur; when it is greater than 30, calcium deficiency occurs. That is to say, when 25 kg of urea is applied per mu, 10 kg of quicklime must be applied so that grapes do not show calcium deficiency; supplement calcium through the leaves during the grape softening and coloring stage.
At this stage, calcium absorbed by the root system can no longer meet the fruit's demand for calcium. If calcium fertilizer is not applied to the leaves, the fruit will show late-stage calcium symptoms. Generally, a mixture of 0.3-0.4% calcium chloride or calcium nitrate and 0.1% boric acid can be selected and sprayed on leaves and fruit clusters, once every 7-10 days, for 2-3 consecutive sprays.
Remove the bags 10-15 days before maturity, and irrigate once 15 days before removing the bags to ensure the soil is moist and promote calcium transport within the grape plant; from the coloring stage to the maturity stage, irrigation should be strictly controlled, and irrigation should stop 20 days before harvest, which helps increase fruit firmness and sugar content at maturity, especially for grapes grown under rain-shelter cultivation.
In the later stage, black plastic film should be used to cover the bed surface to ensure that soil moisture does not change much and to prevent the soil from alternately drying and wetting before and after rain. After rain, drain water from the vineyard promptly to prevent fruit cracking during the grape maturity period.
2. What problems easily arise when fertilizing after grape harvest?
1. Not applying autumn fertilizer or applying it at the wrong time
Although we have always emphasized the importance of autumn fertilization, many growers are busy selling grapes in autumn, so they simply skip autumn fertilizer, while some apply it very late or wait until spring. Here it is emphasized again that no matter how busy you are, autumn fertilizer for grapes must be applied, and it should be applied as early as possible after grape harvest, so that absorption and utilization rates are high.
2. The manure (organic fertilizer) applied is not decomposed or is applied in the wrong place
Whether it is chicken manure, pig manure, or sheep manure, it must be fully fermented and decomposed when applied; otherwise, a series of problems such as root burn and breeding of root diseases and pests will occur. In addition, autumn fertilization must be done by trenching or hole application, and manure must not be directly broadcast on the soil surface.