First, the reasons for falling
1. Variety characteristics. For example, Kyoho cultivar has genetically incompletely developed ovules, and the ovule abnormality rate is as high as 48%, and its filaments are recoiling to the back, which is not conducive to pollination. Some species are defective in female flower structure, and some are degraded in stamens. Unreasonable allocation of pollinating trees in female flower varieties can cause flower drop and fruit drop.
2. The tree stores insufficient nutrition. The lack of nutrients in the storage of the grapes during the early growth period of the grapes causes incomplete flowering period, poor embryonic development, and low pollen germination rate, resulting in fruit drop. Due to the large amount of flowers in the grapes, the consumption of water and nutrients is also very large. When trace elements, especially potassium, phosphorus, boron and other elements are missing during the flowering period of grapes, the fertilization ability of the flowers will be reduced, resulting in fruit drop and fruit drop.
3. Improper cultivation and management measures. The fertilization scheme was unreasonable. The excessive nitrogen fertilizer before flowering, excessive watering during flowering, improper pruning, new shoot binding, picking up the heart, and whole plantation were improperly implemented. The contradiction between vegetative growth and reproductive growth in the flowering period was aggravated, resulting in fruit drop and fruit drop. Spraying flowers during flowering can burn the stigma and affect fertilization, resulting in fruit drop.
4. Weather factors. 1 flowering temperature. The optimal temperature for grape flowering is 20-25°C. If the temperature is lower than 10°C before flowering, it will affect the normal differentiation of flower buds; the flowering temperature is lower than 14°C, the flowering device will be stunted and fall off; the flowering temperature will exceed 35°C, which will easily cause wilting and necrosis of flowers. . 2 flowering rainfall. During the flowering season, even the rainy weather makes it difficult for the corolla to fall off, and the anthers do not normally loosen the powder. 3 Insufficient sunshine. The continuous oligosity before flowering reduced the assimilation of shoots, and the supply of nutrients in the ear during the flowering period was tight.
5. Physiological fruit drop. When the grape's fruit grows to 3-4 mm in size, part of the fruit will fall off due to malnutrition and it will be called a physiological fruit drop.
Second, preventive measures
1. Choose a good variety. Select disease-resistant grape varieties with better flower development and female flower varieties should be equipped with pollination trees.
2. Supplement tree nutrients. Most of the nutrient supply of the grapes is completed in the early growth stage. The best time for nutrient replenishment is after harvesting and before cold-proofing. Generally, early and mid-maturing grapes are harvested, and late-maturing grapes are harvested before harvesting. The latest is in early October. . Human feces and urine, livestock and poultry excrement, compost, and manure were the main components. Two-thirds of the total amount of nitrogen fertilizer and half of the total amount of phosphate fertilizer and potash fertilizer were used as base fertilizer.
3. Reasonable application of nitrogen fertilizer. The internal conditions of the tree that cause flowering and fruit drop are high water-soluble nitrogen content in shoots and low carbohydrate content during flowering, which induces vigorous growth of new shoots. Therefore, nitrogen fertilizer should be reasonably applied. Before flowering (as far as possible), no nitrogen fertilizer and early base fertilizer should be applied. Grapes like fertilizer and water, require more application of organic fertilizer, enhance tree vigor, but some varieties such as Kyoho is very sensitive to nitrogen, once too much nitrogen, especially after a large number of nitrogen after flowering, easily lead to shoots prosperous, causing falling flowers and falling fruit, so the flowering No nitrogen fertilizer is applied before, and after the young fruit is settled and after the harvest in autumn, nitrogen fertilizer is applied. The spring fertilizer is applied early before germination. Therefore, top-dressing should grasp three crucial periods before germination, end of physiological fruiting, and berry coloring. The first two were mainly nitrogen, phosphorus and potassium, and the third was phosphorus and potassium fertilizers. In order to prevent sprouting after sprouting, germinating fertilizer may be exempted under sufficient conditions of basal fertilizer.
The irrigation should be controlled from 3-5 days before flowering to the flowering period. Drought or flooding should be avoided during the flowering period, otherwise it is easy to cause flowering and fruit drop. After you spend it, you must use reasonable irrigation.
4. Leaf spray boron. Boron promotes pollen germination and pollen tube elongation, facilitates the completion of pollination and fertilization, and allows the crown to fall off normally, thereby increasing the rate of fruit set. In the bud stage, early flowering stage and full flowering stage, 0.3% boric acid solution was sprayed once. The effect of adding 0.3% potassium dihydrogen phosphate was better. However, to prevent phytotoxicity, the same weight of lime can be added to the boric acid. For severe boron deficiency, apply 1 kg of borax and 25 kg of fine soil around the plants before germination in early spring.
5. Scientific pruning. Unreasonable pruning can cause excessive or excessively weak shoots, which is one of the causes of falling flowers. It is necessary to scientifically spend thinning and fruit thinning, reasonably leave branches and leave fruit, and load reasonably to maintain a stable tree vigor. In order to effectively prevent falling flowers and falling fruits, we must rely on strong branches and light shears, weak branches and heavy cuts, moderate strength, and support for the weak and maintain the principle of the golden mean.
(1) wipe buds. The principle is a re-wiping of the weak tree, and the tree is a strong hand. In two separate sessions, the sooner the better the first time, it can be carried out after the buds have inflated, and the second time it is carried out at the time of leaf development. The double buds, small buds, malformed buds, and diseased buds are erased, and full round buds are preserved.
(2) sparse. The principle is to stay small and stay strong. It is carried out twice. The first time it takes about 10 centimeters when the new shoot grows. The second time it takes about 20 centimeters when the new shoot grows. According to the size of the space on the shelf, the vines on the main side and the growth of the resulting mother branches will be used to lean. A new shoot is left every 10 centimeters for fence cultivation, and 20 new shoots per square foot are planted on scaffolding. Robust growth of the main lateral branch, the result branch ring can be more appropriate to leave the results of the branch; thick results of the mother branch can leave 2-3 results each branch, the mean can stay 1-2 result branches, leaving only a result of the weak branch Or change the inflorescence into vegetative shoots.
(3) Sparse inflorescences. According to the load and the growth condition of new shoots, the redundant inflorescences can be removed timely, and the strong branches can retain two inflorescences. Generally, the fruit branches leave one inflorescence and the weak branches do not stay. 7-10 days before flowering, the tip of the left inflorescence was cut off 1/4 or 1/5, while the spikelets of the spikelets and spikes were also cut off, leaving 10-12 spikelets in the middle of the inflorescence.
(4) Topping up. The focus should be on moderation. The fruiting rate of the strong fruiting branches and the strong topping heart is high, and the fruit quality is also good. For the intermediate fruiting branches, the weakest toppings are the best. 7-10 days before flowering, the shoots of overgrown fresh shoots can be properly postponed for weak development branches. 5-6 days before flowering to implement the results of the topping, in order to retain 5-7 functional leaves above the inflorescence is appropriate, while the removal of the heart should remove the tendrils and erase the secondary shoots, the infraorbital below all eradication of the inflorescence, in addition to the top of the inflorescence Auxiliary shoots leave 5-7 leaves to pick up the heart, while other side shoots leave 1-2 leaves repeatedly topping. Picking should be carried out at a blade size of 1/3. For strong growth potential branches, the upper tip of the inflorescence before flowering can increase the percentage of fruit set by about 20%.
(5) vine girdling. The girdling time is generally 5-6 days before flowering, and the girdling part should be selected in the front 3cm or the previous joint of the fruiting branch, and can be done with a double-edged ring-stripping knife or a bud grafting knife. The stripping width is 2-3 mm and the depth is up to the xylem. After removing the stripping, it can be tightly packed with clean plastic film strips. The girdling is only suitable for the growth of vigorous plants and shoots, and is limited to the use of the results of the branch, should not be carried out on the main vine.
6. Spray conditioner. This point is mainly used for the tetraploid varieties such as Kyoho which are easy to fall and fall, and diploid species are not suitable. Spraying 300 times of B9 or 250-300 times of PBO liquid on the leaves 10 days before flowering can significantly increase the fruit setting rate.
7. Prevent physiological drop. Physiological fruit drop is a natural fruit scramble for nutrition, which can improve the fruit quality of grapes. However, in order to prevent excessive shedding, young shooters should be controlled in time. At this time to less watering, avoid applying nitrogen fertilizer, topdressing phosphate fertilizer and potash fertilizer.
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