How to remedy the freezing injury of fruit trees caused by "late spring cold"

The frequent occurrence of "cold spring" has hurt fruit farmers. Every spring from late March to early April, just before and after the flowering of peach, apricot, cherry, apple, pear and other fruit trees, this period encounters "late spring cold", which will cause different degrees of freezing damage and even lead to serious yield reduction of fruit trees. Below, let's talk about the prevention and remedial measures of "cold spring" in the flowering period of fruit trees.

"Indigenous method" predicts "late spring cold" and prevents it. Fruit farmers should first pay attention to listening to and watching the weather forecast, and they can also check the weather forecast for a week online. In addition, there is also a simple and feasible "indigenous method" in production to judge the occurrence of "late spring cold". Taking Taoyuan as an example, the following methods can be adopted:

First, the thermometer prediction method. When the temperature drops to 2℃, it will frost after 20 minutes. Knowing this, you should be careful. In the morning, the weather is clear and there is a weak north wind. The weather suddenly turns cold in the afternoon, the temperature drops sharply, and there may be frost in the middle of the night. Or the southeast wind blows during the day and suddenly turns to the northwest wind, but there is no wind or light wind at night, the sky is cloudless in Wan Li, and there may be frost in the middle of the night; Or the north wind blows for a few days, the weather is very cold, suddenly calm, cloudless or partially cloudy at night, and there may be frost in the middle of the night.

Second, wet cloth prediction method. Sometimes cold air comes and wet cloth is hung in the orchard. When there are small white water droplets on the wet cloth, it usually frosts after 1 hour.

Third, the iron prediction method. When frost appears on clean iron, it usually happens after 1 hour.

How to prevent "late spring cold" Generally speaking, orchards located in low-lying areas and valleys are prone to accumulate cold air, causing late frost and freezing injury. Planting trees on ridges, hills, slopes and sunny slopes has less chance of freezing injury. Therefore, when building a garden, we should try to avoid low-lying areas and valleys.

In addition, the occurrence of late frost has certain regularity in different places. Therefore, selecting fine varieties with late flowering period to avoid freezing injury at flowering period can also effectively reduce freezing injury of fruit trees in spring. For example, apricot can choose Golden Sun, and peach can choose Chun Xue.

The above measures are aimed at long-term prevention. In order to avoid freezing injury in a short time, fruit farmers can adopt the technology of delaying flowering. First of all, we should pay attention to listening to the weather forecast, observing the flowering period, and be prepared to postpone the germination and flowering of fruit trees at any time.

Generally speaking, irrigation before flowering 10 day can significantly reduce the ground temperature and delay germination. Irrigation 1-2 times from germination to flowering can generally delay flowering for 3-4 days. Irrigation before late spring cold can increase ground temperature and prevent and alleviate freezing injury.

Whitening the trunk and branches 20 days before flowering can also reduce the absorption of solar heat and delay germination and flowering. According to the investigation, painting the trunk and branches white can delay the flowering period by 3-5 days. The formula of whitening agent is: quicklime 10 kg, sulfur powder 1 kg, salt 1 kg, vegetable oil 0. 1 kg and water 20 kg.

Artificial improvement of orchard microclimate is also a common control method.

Such as heating method. In large orchards, a heater is placed every once in a while to ignite and heat before the late frost comes. You can also heat the orchard in the following ways:

Smoking law. Smoke can be crop stalks, weeds, fallen leaves, etc. And can also be used as an anti-frost smoke agent. The formula is: 20%-30% of ammonium nitrate, 50%-60% of sawdust, 0/0% of waste diesel oil and 0/0% of pulverized coal, which are mixed uniformly and then bagged for later use. When frost is predicted, put it into the orchard and light it in the wind at 2-4 am, generally 5 to 10 pile per mu. It should be noted that if the temperature is below -3℃, the effect of this method is not obvious.

Blowing method A pole with a height of about 10 meter is erected in the orchard at regular intervals, and a blower is installed on it. Before the frost came, the blower was turned on to blow away the cold air.

Water spraying method. High-pole sprinkler irrigation is a water-saving irrigation facility, and the frost damage prevention effect is also good. Use it to spray 0.5% sucrose water, or spray water on branches temporarily when frost comes, which can reduce freezing damage. In addition, spraying Bihu 15000 times during the flower bud expansion period can also improve the frost resistance of fruit trees.