How to prevent late spring cold damage during the pear tree flowering period

Spring late cold spells and frosts are very harmful to pear trees. Generally, when pear trees encounter a low temperature of -4.0°C at the bud stage or -2.3°C to -2.9°C at the flowering stage lasting more than half an hour, the flower organs will suffer freezing damage, usually manifested as poor pollination, dried and dead stigmas, and browned filaments or ovaries. To prevent freezing damage during the pear tree flowering period, the following measures should be taken:

1. Whitewashing the trunk in early spring In early spring, whitewash the main trunk of fruit trees with a self-prepared whitewash agent, which can effectively reduce the absorption of solar heat, delay sprouting and flowering, and has effects such as preventing cold and freezing damage and preventing trunk pests from laying eggs. The preparation method of the whitewash agent is: quicklime 5 kg, sulfur powder 0.5 kg, salt 1.5 kg, vegetable oil 0.1 kg, flour 0.5 kg, water 15 kg. When preparing, first dissolve the lime and salt separately in hot water, stir into a paste, then add the sulfur powder, vegetable oil and flour, and finally add the water and stir evenly.

2.. Irrigation before flowering and spraying water during flowering Irrigate 10 days before pear trees bloom in spring, which can significantly lower the ground temperature and delay sprouting. After sprouting and before flowering, irrigate another 1 to 2 times, which generally can delay flowering by 3-4 days. Irrigating before a late spring cold spell can also raise the ground temperature, preventing and reducing freezing damage. When frost arrives, use the water-spraying method to improve the local microclimate, raise the air temperature, and prevent flower freezing.

3. Smoking method During the pear tree flowering period, the smoke method can be used to prevent frost, with very good results. The smoke agent formula is: ammonium nitrate 20%, sawdust or residual grass and fallen leaves 70%, waste diesel oil 10%. The smoke agent can be placed in 3 to 4 piles per mu, placed at the windward side or evenly placed within the orchard. When the air temperature at a height of 2 m in the orchard drops to -2°C, it can be ignited to release smoke.

4. Releasing bees in the orchard Introduce bee colonies 3 to 4 days before the pear tree flowering period, with one box of bees per 4 to 5 mu. According to experiments, the average frost damage reduction rate in bee areas of pear orchards is more than 40%.

5. Spraying fruit tree antifreeze agent 1 to 2 days before the arrival of late spring cold and late frost, spray fruit tree antifreeze solution plus PBO solution each at 50 to 100 times dilution, and the antifreeze effect is excellent. For fruit trees that are blooming, spray a solution of 0.4% monopotassium phosphate plus 0.2% borax plus 1.8% Aiduoshou, which can enhance the cold resistance of the stamens, reduce the harm of late spring cold, and increase the fruit-setting rate.

6. Spraying self-made antifreeze solution Use agar 8 parts, glycerol 3 parts, glucose 43 parts, sucrose 45 parts, other nutrients (including fertilizers, plant hormones, etc.) 2 parts, and clean water 2000 parts. First soak the agar in a small amount of water for 2 hours, then heat to dissolve, then add the other ingredients, and after mixing evenly it can be used.