What should be sprayed on apple trees that drop flowers and fruit to increase the fruit-setting rate?

During the growth of fruit trees, the phenomenon of flower and fruit drop occurs from time to time, which reduces the yield of the fruit trees and greatly reduces the income of the fruit growers.So what should be done about apple flower and fruit drop? What should be sprayed? How can the fruit-setting rate be increased?

What should be done about apple flower and fruit drop?

1. Vigorously promote autumn application of base fertilizer in orchards to increase the tree's stored nutrients

In recent years, some fruit growers have not paid attention to applying base fertilizer in autumn, and orchard management has been neglected before and after fruit harvest, resulting in a serious shortage of stored nutrients in the trees. In autumn, the roots of fruit trees have a growth peak, and supplementary nutrients must be provided before and after fruit harvest. Autumn base fertilizer is mainly organic fertilizer, at 1.5 jin of organic fertilizer per jin of fruit, with a small amount of chemical fertilizer appropriately applied. The best time to apply base fertilizer is from late September to early October. Because the stored nutrients in fruit trees mainly come from the products of leaf photosynthesis before and after fruit harvest, to increase the tree's stored nutrients, it is necessary to vigorously promote autumn application of base fertilizer in orchards.

2. Improve pollination conditions

1. Set up pollinizer trees or pollinizer branches. In view of the current problem of variety purification, in newly developed orchards, pollinizer trees should be set up at a ratio of 10:2. In orchards that are bearing fruit or about to bear fruit, the method of top grafting to change the head should be used, with 1-2 pollinizer branches per tree to solve the problem of poor pollination. For the Fuji series, New Red Star and Orin are the best pollinizer varieties.

2. Promote mason bee pollination. Mason bee pollination is very effective. Zhaoyang District also promoted it in 2005 and 2006, but later, due to problems with bee tube storage and other aspects, the promotion of this technology did not succeed in Zhaoyang District. To avoid large-scale flower and fruit drop, this technology should be reintroduced and promoted more strongly in the future, and continuously summarized and improved during promotion.

3. Place bees in orchards. Few fruit growers in Zhaoyang District keep bees. If beekeepers from other places can be organized to place bees in orchards in our township during the apple flowering period, it would benefit not only fruit growers but also beekeepers, achieving multiple benefits at once. At the same time, it can also encourage some fruit growers in our district to keep bees, gradually achieving the goal of self-sufficiency in orchard bee pollination.

4. Promote artificial pollination. Before flowering, first collect unopened “bell flowers”, take the anthers and heat them in a greenhouse or incubator to 20-25℃ to dry and collect pollen, place it in a bottle, and store it in a low-temperature dry place for later use. When flowering begins, use a brush or other tool for spot pollination. Each dip of pollen can pollinate 5-10 flowers. This method is very effective.

What should be sprayed on apple trees that drop flowers and fruit?

1. Spray fertilizer during the flowering period. When 30% of the central flowers have opened, spray a 0.2%-0.3% urea solution; during the bud stage or flowering period, spray a 0.1%-0.2% borax solution. The two can be mixed and sprayed, and can effectively increase the fruit-setting rate; a 1:2 biogas slurry can also be sprayed on the flowers to protect flowers and fruit.

2. Spray sugar during the flowering period. Spraying 2%-3% brown sugar water or white sugar water during the flowering period to attract insects for pollination can also increase fruit setting.

How can apples increase the fruit-setting rate?

1. Strengthen field management. Strengthening field management and improving the tree's nutritional level are the basic ways. For deciduous trees, the nutrients required during the flowering period are mainly stored nutrients. First, attention must be paid to measures such as topdressing after harvest, irrigation, and pest and disease control to improve photosynthetic efficiency, accumulate stored nutrients, and improve flower bud quality. In addition, spring management must be strengthened, with early topdressing, irrigation, and tillage to ensure the nutrients needed for flowering and fruit setting.

2. Create good pollination conditions. For cross-pollinated varieties, the foundation is to rationally configure pollinizer trees, and a series of auxiliary measures should also be taken.

(1) Place bees during the flowering period. Increasing the number of bees in the orchard during the flowering period of insect-pollinated flowers has an obvious effect on improving the fruit-setting rate. Bees should be placed in the orchard by setting up hives before flowering. Generally, 1 hive is placed per 0.33-0.67 hm2 of apple orchard. Because bees have the habit of flying along rows, hives should be placed in each row or every few rows, with a general distance of 100-150 m between hives. During the flowering period, insecticidal pesticides must never be sprayed to prevent bees from being poisoned to death.

(2) Top graft flowering branches. In orchards lacking pollinizer varieties, top graft pollinizer varieties with flower buds into the canopy to increase the pollination rate. For trees, the principle of configuring pollinizer trees can also be followed to top graft and replace part or all of the trees in a single-variety orchard with pollinizer varieties.

(3) Hang jars and shake flowering branches. In orchards lacking pollinizer varieties, at the beginning of flowering, cut flowering branches of pollinizer varieties, insert them into water jars or wide-mouthed bottles, and hang them on trees that need pollination to improve pollination efficiency. At the same time as hanging jars, cut flowering branches can be tied to poles and extended to the top of the canopy, and the poles lightly shaken so that pollen falls and pollination occurs.

3. Artificial supplementary pollination. When pollinizer varieties are lacking or the weather conditions during the flowering period are poor, artificial pollination should be carried out. Artificial pollination must grasp the timing. According to research, pollinating each flower is often beneficial for fertilization and fruit setting. The flowering period must be predicted in advance based on the phenological period of previous years and changes in spring temperature and humidity, and pollen must be prepared in advance to ensure timely pollination and save pollen usage. According to the pollen germination rate, dilute the pollen 5-10 times (adding talcum powder or starch). For artificial spot pollination of stigmas, liquid pollination can mix pollen into 5% sugar solution and add 0.3% urea and 0.1% boric acid. Add 10-12 g of pollen to 5 kg of sugar solution. The pollination liquid should be prepared and used immediately, and should not be left standing.

4. Apply regulators. The direct cause of flower and fruit drop is the formation of an abscission layer at the base of the fruit stalk. The formation of the abscission layer is related to insufficient endogenous hormones (gibberellin, auxin, etc.). Therefore, spraying synthetic regulators during the flowering period or on flowers can increase the content of these substances in young fruits, prevent the stalk from producing an abscission layer, and improve the fruit-setting rate.

5. Measures such as summer pruning and pest and disease control to improve the fruit-setting rate.