To do a good job in preventing and controlling night frost damage, the following points must be taken into account:
I. Climate conditions
Night frost damage seems to have suddenly occurred, but it is entirely determined by the climate at that time, and its appearance has obvious signs. There are two main points:
1, warm winter. Should pay special attention to the appearance of warm winter. Due to the influence of warm winter, the phenology period of fruit trees is greatly advanced, and the later the occurrence of late frost damage, the more serious the damage will be. In 2002, the phenological period of fruit trees in our city was about 15 days ahead of schedule, and about 10 days earlier in 2004. Late frost damage occurred in late April, and the damage was very serious. This year's phenology period is nearly 20 days ahead of schedule.
2, continuous northwest wind. If the northwesterly wind blows for 2 to 3 consecutive days in the middle and late April, sudden sudden winds occur in the evening, and frost damage is most likely to occur. The three serious night frost damages in 2002, 2004 and 2005 were all continuous after the northwest wind. The temperature dropped sharply and the low temperature effect was long. Therefore, when the above climate features occur, precautions should be actively taken.
Second, the phenology period
As the phonological period advances, the antifreeze capacity of the tree declines, and the greater the possibility of freezing damage, the greater the loss.
Third, the geographical environment
The degree of harm caused by frost damage in late nights also depends on the geographical location of the orchard. Judging from the occurrence of frost damage in recent years and the investigation of the degree of damage, it mainly occurs in the following three types of orchards: coastal orchards (orchards heavier to the west of the 264 national highway); riverbank orchards (hetao orchards occur heavier); orchard (grooves) Orchard occurs heavier.
Fourth, preventive measures
1, robust tree. Maintaining a robust tree is the basis for doing a good job of prevention. According to the results of the survey, trees with weak tree vigor and heavy flowers are particularly affected by heavy damage, while strong tree vigor, moderate flower volume, and light leaf damage are light. Therefore, it is necessary to grasp the basic management of the orchard, and to eliminate excessive inflorescences and increase tree vigor in time for trees with large amounts of flowers and weak trees. In addition, the investigation of the extent of damage to the coastal cherry orchard shows that the main branch has a small angle, a relatively small degree of cold damage, a large angle, and heavy damage. Therefore, the main branch angle should not be too large for the orchards (coastal, Hetao, and Shangao orchards) with heavy frost damage.
2. Delay the phenological period of fruit trees. In early spring, the use of cultivation measures to delay fruit sprouting and flowering time, can take two ways: First, winter and spring tree white, delay germination and flowering; Second, after germination 2 to 3 times, especially spring drought, climate change Large, it should increase the number of watering to delay flowering time.
3, do a good job of emergency protection measures. The best preventive measures are watering the orchards, followed by the orchards. If there is a continuous northwesterly wind, and the temperature drops to 5 to 6°C during the daytime, there are watering conditions in the orchards, and the gardens should be placed in water. When the temperature drops to 2 to 3°C in the evening, the orchards must be smoked. The orchards with poor irrigating conditions should pay more attention to smoking. At present, there are mainly three problems in production.
(1) Improper release of tobacco. Turn smoke into arson. The real anti-cold effect is smoke, which is a mixture of smoke and water vapor, so that the smoke ratio is large, the specific heat is high, and the antifreeze effect is obvious. In order to produce high-quality smoke, weeds are alternately layered when the grass is placed.
(2) The timing of smoking is not correct. Many orchards emit smoke too late, and the temperature drops below zero until they start to emit smoke. It is too late and the effect is poor. According to the requirement, when the night temperature drops to 2~3°C, the smoke will start to be released, so as to better play the role of freezing.
(3) Insufficient number of tobacco plants. The orchards of frost-tolerant ground-breaking patches should, as far as conditions permit, be put as much as possible to ensure the quantity and quality of the tobacco piles. When there is no wind, the grass piles are evenly distributed in the field, and the breeze must be in the upwind, linear stacking, in order to improve the prevention effect.
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