What are the preventive measures for the late spring cold of vegetables, wheat and fruit trees?

"Late spring cold" is a weather phenomenon in which the temperature in early spring is lower than that in the same period of normal years, and crops often suffer from freezing damage. This kind of weather "big face" is very unfavorable to agricultural production, if the prevention is not timely, it is easy to let the crops freeze. So, vegetables, wheat, fruit trees late spring cold preventive measures what?

1. Vegetables

Early spring vegetable cultivation is mainly based on facilities and protected areas, generally planting solanaceous fruits, melons, beans, green leafy vegetables, etc. Due to the large amplitude and fast cooling speed, it is difficult for vegetable seedlings to adapt, and the longer the duration, the heavier the damage. Short-term cold wave damages the aboveground part of vegetables, and long-lasting cold wave damages the underground part. When it is serious, it will cause freezing injury, flower and fruit drop, resulting in dead seedlings; at the same time, it also makes some infectious diseases easy to occur and spread. The control of vegetables in late spring was divided into three parts: first, vegetables were injured in seedling stage, second, vegetables were injured in adult stage, and finally, vegetables were injured in flowering and fruiting stage. In the face of these three different growth periods of vegetables, we should have different control measures.

1. Damage at the seedling stage

(1) Victimization

Damage to cotyledons: The edges of cotyledons lose their green color and grow normally when temperature returns.

True leaves are damaged: the edges of the leaves appear dark green and slowly dry out.

Damage to the growing point: the terminal bud will be frozen, and new leaves will not grow at this time, so that the plant's seedling stage will be greatly extended. If the weather gradually returns to temperature and the injured plant cannot recover, it is necessary to carry out supplementary seedlings at this time.

(2) Countermeasures: Cultivate strong seedlings. It is best to temper seedlings at low temperatures, which can effectively improve the frost resistance of vegetable seedlings, even if the late spring cold occurs, it can also minimize the impact of cold on seedlings.

2. Damage in adult plant stage

(1) Damage performance: often showing dry edges, plants become withered, young leaves lose green and turn yellow, etc. Severe freezing will cause the growing point to dry up, and the root system of the plant will not grow new roots.

(2) Countermeasures: First of all, it is not the external conditions, but the plant itself. Only the healthy vegetable plants can mitigate the losses when they suffer from late spring cold, because the healthy plants will suffer much less. Therefore, it is important to cultivate healthy plants.

First of all, we should do a good job of squatting seedlings of vegetables, secondly, let the roots of vegetables grow healthily, and thirdly, it is an important fertilizer and water problem. No matter what kind of plant, we must ensure the nutrients in its middle growth period, because fertilization can ensure the development of roots and make the plants healthy, so topdressing treatment is generally carried out on vegetables.

3. Suffering during flowering period

(1) Damage performance: When vegetables suddenly suffer from cold or cooling when they bloom, they will reduce the pollen activity of vegetables, which will indirectly affect pollination, fertilization, etc., and will also cause flowers and fruits to fall in the later stage. Flowering will also make flower bud differentiation poor, will directly lead to the emergence of abnormal fruit growth. Severely damaged melon vegetables will also have flower tops.

(2) Response measures:

Vegetables that are in bloom are relatively delicate. As long as they are injured, they are easy to drop flowers and fruits, and even if they bear fruits, they will be deformed. Therefore, the work to be done well in this period is to carry out prevention in order to ensure the flowering and fruiting of vegetables.

First of all, pay attention to the local weather in a timely manner. Don't just look at the weather for these two days. Be sure to look at it for a few more days. It's best to look at it for the last half month so that we can take better preventive measures. Do not water when the temperature begins to change to avoid freezing damage. Prepare vegetables in time for items needed to survive the cold.

Secondly, in the late spring when the arrival of timely insulation, vegetables have temperature stability can be. There are many measures that can be taken, such as erecting some wind barriers and covering vegetables with plastic film. One of the recommended measures here is straw, which can not only protect against cold but also be used as fertilizer. There is also smoking can be carried out for heat preservation, irrigation, temporary warming, etc. can guarantee the temperature before frost can also be cultivated to alleviate freezing damage.

Vegetables have different growth periods, so when the cold comes in late spring, the growth periods of vegetables are different, and the most effective measures should be taken according to different growth periods.

II. Wheat

Generally, the most likely time for cold in late spring is after jointing of wheat, and early-maturing varieties and varieties with weak cold resistance should be taken as key prevention objects.

1. For wheat fields lacking moisture, irrigate water in advance before the arrival of cold wave, improve soil moisture, adjust microclimate in the near layer, buffer the influence of cooling, and prevent freezing damage. The wheat fields with good soil moisture and not yet jointing and the wheat fields with loose soil shall be suppressed to make up for soil gaps, prevent ventilation and moisture loss, and control vigorous growth at the same time.

2. 2-3 days after the cold wave, timely investigate the freezing condition of young ears, classify fertilization and remedy, promote the recovery of growth, strive for small tillers to catch up with big tillers and large tillers to form more ears. For wheat fields where only leaves are frozen or the freezing rate of young ears of main stems is less than 10%, no fertilizer is needed; for wheat fields where the freezing rate is 10%-30%, urea is applied about 5 kg per mu; for wheat fields where the freezing rate is 30%-50%, urea is applied 7-10 kg per mu; for wheat fields where the freezing rate is more than 50%, urea is applied 12-15 kg per mu. Jointing and booting fertilizer should be applied normally.

III. Fruit trees

Late spring cold damage to apricot, cherry, apple, pear, kiwi fruit and other early flowering fruit trees is the most obvious. On the basis of rational fertilization, irrigation, branch pruning and overwintering management, the following control measures should be taken:

(1) Measures taken before the occurrence of cold in late spring

1. Strengthen soil, fertilizer and water management

It is suggested that fruit growers should apply organic fertilizer, compound fertilizer and medium and trace element fertilizer in time, and irrigate in time after fertilization; irrigation and water preservation in orchard can alleviate the adverse effects of tree freezing injury on tree body, improve physiological function, enhance resistance and recovery ability.

2. For those who bloom quickly, water should be poured. Especially when the forecast temperature is below zero. Pay attention to the weather forecast before and after the flowering of fruit trees. Water before the cold spell to reduce the ground temperature and delay the flowering by 2? Three days, these two days there are fruit friends to consult me whether I can water, the weather drought needs watering, even if not drought, now come late spring cold, also need irrigation, improve the frost resistance of fruit trees. To avoid the cold.

3, trunk painted white or sprayed with lime water. Trunk painting white can reduce the freezing damage to the trunk. In recent years, apple, pear, peach, cherry and other trunks have rotted, shed glue and dripped black water. Many of them are frozen. Trunk painting white is helpful to prevent severe low temperature damage. 25 years before the tree blooms. 30 days, spraying 1% lime water, can delay flowering 3? 5 days, a slight delay in flowering can avoid harm. Of course you can't spray when your fruit trees are in bloom.

4. Spray antifreeze

5. Cover the windproof method. Cover fruit trees with plastic sheets, straw curtains, reed mats, etc. to retain the geothermal heat emitted and block the invasion of external cold, thus reducing frost. Many granulated oranges in the south are surrounded by plastic, and the effect is good. This method is most suitable for young orchards or low dry and short crown trees, and it is not easy to do it when the trees are big. Of course, it is recommended that windbreaks be established when building gardens, so that trees can be protected from or less affected by bad weather such as late spring cold and frost, and reduce and alleviate the occurrence of fruit tree freezing damage.

(2) Remedial measures to be taken after the occurrence of late spring cold

1. Artificial pollination and fruit thinning. For flowers that have not been frozen and are blooming, artificial pollination should be carried out in time. Pollen must be collected in advance for future use. In some affected fruit areas, stop thinning flowers and other work, the affected orchard should be carefully thinned after the young fruit is set, select and retain the normal fruit with correct fruit shape and larger fruit, thin out the weak, abnormal and frost-damaged fruit, and some branches should be left properly.

2. Strengthen fertilizer and water management. Especially in low-lying areas where serious freezing damage occurs, quick-acting nitrogen fertilizer should be applied as soon as possible, watering should be timely to promote the growth of fruit trees, and flowers and fruits that are not frozen should be preserved. foliar fertilizer. Late spring cold generally does not freeze the leaves, should be timely spraying foliar fertilizer, such as potassium phosphate, etc., can enhance the photosynthetic efficiency of leaves, manufacture nutrients, ensure the normal growth of fruit trees.