How to prevent grapes from falling flowers and fruits? What's the reason? What kind of medicine should I take?

The flower buds of grapes one week before flowering and the ovary after flowering fall off into falling flowers and fruits, and the rate of falling flowers and fruits is more than 80%, which is called falling flower and fruit drop disease. Then how to prevent grapes from falling flowers and fruits? What's the reason? What kind of medicine should I take? What kind of medicine should I take?

How to prevent grapes from falling flowers and fruits?

1. Select good varieties. In order to select the disease-resistant grape varieties with sound floral organ development, the female flower varieties should allocate pollination trees reasonably.

two。 Replenish the nutrition of the tree. Most of the nutrient supply of grapes is completed in the early growth stage, and the best time to supplement nutrients is from harvest to cold protection, generally early and middle ripening grapes are harvested, and late ripening grapes are applied before harvest, and the latest is in early October. Human feces and urine, livestock and poultry manure, compost and barnyard manure were mainly used, and the total amount of nitrogen fertilizer and half of the total amount of phosphate and potash fertilizer were applied as base fertilizer.

3. Rational application of nitrogen fertilizer. The internal condition of the tree leading to flower and fruit drop is that the content of water-soluble nitrogen in the new shoot is high and the carbohydrate content is low during flowering, which induces the vigorous growth of the new shoot. Therefore, nitrogen fertilizer should be applied reasonably, no nitrogen fertilizer should be applied before flowering and base fertilizer should be applied as early as possible. Grapes like fertilizer and water, and require more organic fertilizer to enhance the tree potential, but some varieties, such as Jufeng, are very sensitive to nitrogen. Once there is too much nitrogen fertilizer, especially a large amount of nitrogen topdressing before flowering, it is easy to cause shoot vines to grow, causing flowers and fruits to fall, so no nitrogen fertilizer is applied before flowering. Nitrogen fertilizer should be applied after young fruit setting and autumn harvest, and topdressing in spring should be applied as early as before germination. Therefore, topdressing should grasp the three key periods before budding, the end of physiological fruit drop and the coloring period of berries. The first two times are mainly nitrogen, phosphorus and potassium, and the third time is phosphorus and potassium fertilizer. In order to prevent the vigorous growth of fruiting branches after germination, sprouting fertilizer can be avoided under the condition of sufficient base fertilizer.

Control irrigation from 3-5 days before flowering to flowering, and avoid drought or heavy irrigation during flowering, otherwise it is easy to cause falling flowers and fruits. Irrigation should be more reasonable after flowering.

4. Boron spray on the leaves. Boron can promote pollen germination and pollen tube elongation, facilitate the completion of pollination and fertilization, and make the Corolla fall off normally, thus increasing the fruit setting rate. 0.3% boric acid solution was sprayed once at flower bud stage, early flowering stage and full flowering stage, and the effect was better if 0.3% potassium dihydrogen phosphate was sprayed. However, in order to prevent drug damage, the same weight of lime can be added to boric acid. For those with serious boron deficiency, 1 kg of borax and 25 kg of fine soil can be mixed well around the plant before early spring grape germination.

5. Scientific pruning. Unreasonable pruning will cause the branches to be too strong or too weak, which is also one of the reasons for falling flowers and fruits. It is necessary to scientifically sparse flowers and fruits, keep branches and fruits reasonably, load reasonably, and maintain a stable tree potential. In line with the principle of light cutting of strong branches and heavy cutting of weak branches, easing the strong, supporting the weak, and maintaining the principle of moderation, can we effectively prevent flowers and fruits from falling.

⑴ sprouts. The principle is the re-erasing of weak trees and the light wiping of strong trees. Divided into two stages, the first time, the earlier the better, after the bud expansion, the second time in the leaf expansion, erase double buds, small buds, deformed buds, diseased buds, and retain round head full buds.

⑵ thinning. The principle is to go to the small to stay big, to the weak to stay strong. It is carried out in two stages, the first when the new shoot is about 10 cm long, and the second when the new shoot is about 20 cm long. But also according to the size of the space of the shelf surface, the growth of the main side vines and fruiting mother branches to thinning. There are about 1 new shoot every 10 cm in the hedge cultivation and 20 new shoots per square meter in the scaffolding cultivation. The main side branch and fruiting branch ring with strong growth can leave more fruiting branches appropriately; the sturdy fruiting mother branch can leave 2-3 fruiting branches per branch, the moderate one can leave 1-2 fruiting branches, and the weak one can leave only one fruiting branch or pinch off the inflorescence to change into a vegetative branch.

⑶ straightens out inflorescences. According to the load and the growth of new shoots, the excess inflorescences can be removed in time, two inflorescences can be left in strong branches, one inflorescence in general fruit branches and no weak branches. 7-10 days before flowering, the tip of the remaining inflorescence was cut off 1 / 4 or 1 / 5, and the spikelets on the accessory spikelet and the shoulder of the spikelet were also cut off, leaving 10-12 spikelets in the middle of the inflorescence.

⑷ picks the heart. For stout fruiting branches, the fruit setting rate of strong coring treatment is high, and the fruit quality is also good. For medium fruiting branches, weak coring treatment is the best. 7-10 days before flowering, the coring of overgrowing new shoots can be postponed appropriately for weakly developed branches. 5-6 days before flowering, it is appropriate to keep 5-7 functional leaves above the inflorescence, remove tendrils and secondary shoots at the same time, erase all the secondary shoots below the inflorescence, and keep 1-2 leaves above the inflorescence except 5-7 leaves above the inflorescence. It is appropriate to pick the heart to the 3-sized leaf of the adult leaf. For the fruiting branches with strong growth potential, twisting the top of the inflorescence before flowering can increase the fruit setting rate by about 20%.

⑸ branches were peeled around. The girdling time is generally 5-6 days before flowering, and the girdling site should be 3 cm in front of the bearing branch or the first Internode, either with a double-edged ring peeling knife or bud grafting knife. The width of the peeling mouth is 2-3 mm, reaching as deep as the xylem. After the peeling is removed, immediately wrap it tightly with a clean plastic film strip. Girdling is only suitable for growing strong plants and branches, and it is only used on fruiting branches, but not on main vines.

6. Spray regulator. This point is mainly used for tetraploid varieties such as Jufeng, which are easy to drop flowers and fruits, but diploid varieties are not applicable. Spraying 300x B9 or 250x-300x PBO solution once 10 days before flowering could significantly increase the fruit setting rate.

7. To prevent physiological fruit drop. Physiological fruit drop is a natural fruit thinning which competes for nutrition, which can improve the fruit quality of grape. However, in order to prevent excessive shedding, the new shoot growth of grapes should be controlled in time. At this time, we should water less, avoid applying nitrogen fertilizer, topdressing phosphate fertilizer and potash fertilizer.

What is the reason for grape falling flower and fruit?

1. Breed characteristics. For example, Jufeng varieties have the characteristic of incomplete ovule development genetically, the abnormal rate of ovule is as high as 48%, and its filaments are rolled back, which is not conducive to pollination. Some varieties have defects in the structure of female flowers, some have degenerated stamens, and the unreasonable configuration of pollination trees of female flower varieties will cause falling flowers and fruits.

two。 The nutrition of tree storage is insufficient. In the early stage of grape growth, the tree storage nutrition is insufficient, which leads to the increase of incomplete florescence, the poor development of embryo plant and the low germination rate of pollen, resulting in fruit drop. Due to the large amount of flowers and the consumption of water and nutrients, when the grapes are lack of trace elements, especially potassium, phosphorus and boron, the fertilization ability of flowers will decrease, resulting in falling flowers and fruits.

3. Improper technical measures of cultivation and management. Unreasonable fertilization scheme, excessive amount of nitrogen fertilizer before flowering, excessive irrigation during flowering, improper implementation of technical measures such as shaping and pruning, new shoot binding, coring, panicle, etc., aggravated the contradiction between vegetative growth and reproductive growth during flowering, resulting in flower and fruit drop. Spraying at flowering stage will burn the stigma, affect fertilization and lead to fruit drop.

4. Meteorological factors. ① flowering temperature. The optimum temperature at flowering stage is 20-25 ℃, if the temperature before flowering is lower than 10 ℃, the normal differentiation of flower bud will be affected; when the temperature is below 14 ℃, the flower organ will fall off; when the temperature at flowering stage is more than 35 ℃, it is easy to cause wilting and necrosis of flower organ. ② rainfall at flowering stage. During the flowering period, the continuous rainy weather makes it difficult for the Corolla to fall off, and the anther can not disperse powder normally. Lack of sunshine in ③. Continuous low light before flowering decreased the assimilation of new shoots, and the nutrient supply of fruit ears was tight at flowering stage.

5. Physiological fruit drop. When the fruit of the grape grows to 3-4 mm, part of the fruit will fall off because of malnutrition and stop developing, which is called the physiological fruit drop of the grape.