Prevention of late spring cold during flowering of pear trees

Cold and frost in late spring do great harm to pear trees. Generally, pear trees encounter a low temperature of-4.0℃ at the bud stage and-2.3℃ ~-2.9℃ at the flowering stage. If they last for more than half an hour, the flower organs will suffer frost damage, usually manifested as poor pollination, stigma drying and death, filaments or ovary browning. The following measures should be taken to prevent frost injury of pear trees at flowering stage:

1. Early spring trunk whitening can effectively reduce the absorption of solar heat energy, delay germination and flowering, prevent cold and frost, prevent branch pests from spawning and so on. The preparation method of whitening agent is as follows: quicklime 5 kg, sulfur powder 0.5 kg, salt 1.5 kg, vegetable oil 0.1 kg, flour 0.5 kg, water 15 kg. In preparation, lime and salt are respectively hydrated with hot water and stirred into a paste, then sulfur powder, vegetable oil and flour are added, and finally water is added to stir well.

2.. Irrigation before flowering and spraying at flowering stage irrigation 10 days before flowering of pear trees in spring could significantly reduce the ground temperature and delay germination. It is generally possible to delay flowering for 3-4 days by rewatering for 1 or 2 times after germination to before flowering. On the other hand, irrigation before the late spring cold can increase the ground temperature and prevent and reduce the freezing injury. When the frost comes, the water spraying method is used to improve the local microclimate, raise the temperature and prevent frozen flowers.

3. Smoke method can be used to prevent frost in pear tree flowering period, and the effect is very good. The aerosol formula is as follows: ammonium nitrate 20%, sawdust or residual grass leaves 70%, waste diesel oil 10%. The aerosol can be placed in 3-4 piles per mu and placed evenly in the upper wind or orchard. When the temperature in the orchard drops to-2 ℃, it can ignite and release smoke.

4. The bee colony was introduced 3-4 days before the pear tree blossomed in the orchard, and the bee was released in a box of 4-5 mu. According to the experiment, the average frost damage rate in the bee area of the pear orchard is more than 40%.

5. Spraying fruit tree antifreeze 1-2 days before late spring cold and late frost, spraying fruit tree antifreeze solution plus PBO solution 50 times of 100 times, the antifreeze effect is excellent. The flowering fruit trees can be sprayed with 0.4% potassium dihydrogen phosphate, 0.2% borax and 1.8% Aido solution, which can enhance the cold resistance of stamens, reduce the harm of late spring cold, and increase the rate of fruit setting.

6. 8 parts of Agar, 3 parts of glycerol, 43 parts of glucose, 45 parts of sucrose, 2 parts of other nutrients (including fertilizer, plant hormone, etc.) and 2000 parts of clear water were sprayed with self-made antifreeze solution. First soak the Agar in a small amount of water for 2 hours, then dissolve it by heating, then add other ingredients, mix well and then use it.