The purpose of blueberry pruning is to regulate the contradiction between reproductive growth and nutrient growth and to solve the problem of ventilation and light penetration. The general principle to be mastered in pruning is to achieve the best yield rather than the highest yield, and to prevent excessive results. Blueberry pruning often results in a reduction in yield, but the single fruit weight, fruit quality increases, maturity earlier, increased commercial value. However, pruning should be prevented from over pruning to ensure a certain yield. The degree of pruning should be determined by the use of the fruit. If processing, fruit size can be, pruning should be light, improve yield; if the market is fresh food, pruning should be heavy, improve commodity value. The main methods of blueberry pruning are flat stubble, thinning, cutting flower buds, flower thinning, fruit thinning, etc. Different pruning methods have different effects.
Pruning of highbush blueberry
1. Pruning In Young Tree Period
The main purpose of this period to go to flower buds is to expand the crown, increase the number of branches, and promote the development of the root system. After planting the second and third years of spring thinning out weak branches and small strips, the third and fourth years are still mainly to expand the canopy, but can be appropriate amount of results. Generally, the third year yield should be controlled at 1 kg or less, with strong branch results.
2. Adult Tree Pruning
After the highbush blueberry into adulthood, the inner chamber is easy to depression, the crown is relatively tall. At this time, pruning is mainly to control the height of the tree, improve the light conditions, pruning to thinning mainly, thinning out too dense branches, weak branches, disease branches, as well as the root system of the tiller. The growth potential is more open tree thinning to weak branches to stay strong branches, upright varieties to the center stem, open the window, and stay mediocre branches. The best fruiting age of large branches is 5-6 years, more than when to retract and renew. Weak branches can be used to wipe the flower buds method of pruning, so that it turned strong. Adult trees have a large number of flower buds, often using the method of cutting flower buds to remove part of the flower buds, generally 2-3 flower buds per strong branch cut.
3. The Old Tree Update
Planted about 25 years, blueberry tree above ground part of the tree has senescence, at this time the need to update the whole tree, that is, close to the ground will be sawed off all the above ground part, generally do not leave stakes, if you leave stakes, the highest not more than 2.5 centimeters. In this way, from the base to sprout new branches. The whole tree renewal after the year does not bear fruit, the third year yield can be 5 times higher than the non-renewal tree.
Dwarf Blueberry Pruning
The principle of dwarf blueberry pruning is to maintain the strong tree, strong branch results. There are two main pruning methods: burning and stubble.
1. Burning Cut
That is, in the dormant period of the ground part of all burned off, re-emergence of new branches, the formation of flower buds, the second year of flowering and fruiting. After that, every two years to burn cut once, always maintain the strong branch results. Burning shear after the year no yield, the second year yield
Quantity than not burned cut yield doubled, fruit size, good quality. After burning shear is conducive to mechanized harvesting, can eliminate weeds, prevent pests and diseases. Burning shear should be carried out in early spring before sprouting. Burning cut, the field can be sown leaves, straw to help burn.
Burning shear should pay special attention to prevent fire, planted in the forest area of the blueberry should not be used this method.
2. Flat Stubble
In early spring before budding, from the base of the plant to the ground part of the flat stubble, all sawed off. Sawed off the branches retained in the orchard, can play the role of soil cover and improve the content of organic matter, thereby improving the soil structure, conducive to the root system and rhizome growth.
Rabbit Eye Blueberry Pruning
The pruning of rabbiteye blueberry is basically the same as that of highbush blueberry, but attention should be paid to controlling the height of the tree, to avoid too high a crown is not conducive to the management and fruit harvest.
Soil, fertilizer and water management
The blueberry root system is shallow and slender, without root hairs, so the soil is loose and well ventilated.
1. Clear Tillage
Cultivating highbush blueberries on sandy soils uses clear-tillage for soil management. Clear plowing can effectively control the competition between weeds and trees, and promote the development of trees, especially in the period of young trees, clear plowing is especially necessary. The depth of clear-tillage is 5-10 centimeters. Research on Cabot varieties found that shallow plowing of 5-10 cm increased yields by 6%-60% compared to 2.5-5 cm. The reason for this is that shallow plowing makes the soil underneath the tilled layer compacted and restricts the development of the root system, while deeper plowing loosens the lower layer of the soil and promotes the development of the root system to depth and breadth. However, clearing should not be too deep, in the field soil of Zhejiang region, the soil layer below 30-50 cm is often sticky and heavy loess layer, clearing too deep will turn the loess layer to the upper layer of the soil and destroy the soil structure, which is not conducive to the development of the root system. Therefore, the height of the tools used for blueberry tillage is generally no more than 15 cm. On the other hand, blueberry root distribution is shallow, too deep plowing is not only unnecessary, but also cause root damage.
2. Taiwanese Field
Cultivation of blueberries in low-lying, waterlogged, poorly drained soils (such as meadows, swamps, wetlands) needs to be carried out on the terrace. After the field, the aeration of the table surface is improved, while the ditch is waterlogged. This ensures the availability of soil moisture and prevents stunting of the tree due to waterlogging. However, after Taitian, the surface of the platform plowing, weeding is not conducive to mechanical operation, but need to be completed manually.
3. Grass cultivation
Grass cultivation of soil management in blueberry cultivation is also applied, mainly between the rows of grass, while the rows with herbicides to control weeds. The raw grass method of management can obtain the same yield effect as the clear-cut method. Compared to the clear-till method, the raw grass method has significant soil moisture retention and is suitable for dry and clay-heavy soils. With the haying method, the early morning crop decays and accumulates on the surface each year, forming a layer of mulch. Another advantage of the raw grass method is that it is easy to work in the orchard and walk with machinery. Its disadvantage is unfavorable to the control of blueberry stiff fruit disease.
4. Soil Cover
Blueberries require acidic soils and lower terrain conditions. Therefore, when the soil is dry, high pH and insufficient organic matter content, it is necessary to take measures to regulate the moisture and pH of the upper soil layer. In addition to soil incorporation of organic matter, soil mulching techniques are widely used in production. The main function of soil mulching is to increase soil organic matter content, improve soil structure, regulate soil temperature, maintain soil moisture, reduce soil pH, control weeds, etc.. Dwarf blueberry soil cover 5-10 cm sawdust or pine needles, in 3 years the yield can be increased by 30%, single fruit weight increased by 50%, the application of more soil mulch is sawdust, especially easy to decompose softwood sawdust is good. After the soil is covered with sawdust, the blueberry root system develops well in the layer of decayed sawdust, so that the root system expands to the breadth and expands the surface of nutrient and water absorption, thus promoting the growth of blueberries and improving the yield.
The use of well rotted sawdust is better and more effective than new, undecomposed sawdust, and the decomposed sawdust can quickly lower the soil pH. Soil mulching results are even more effective when combined with soil amendments incorporating charcoal. The use of soil mulch resulted in an increase in blueberry root growth as evidenced by an increase in root distribution depth, distribution diameter, and root dry weight. The moss treatment resulted in a nearly 1-fold increase in root depth and a 4-fold increase in root dry weight. Mulching with sawdust can be done right after the seedlings are planted. The sawdust is evenly covered on the bed with a width of 1 meter and a thickness of 10-15 cm, and then 2.5 cm thick every year to maintain the original thickness. If the application of new sawdust is not decomposed, it is necessary to apply 50% more nitrogen fertilizer. If well-rotted sawdust is used, the amount of nitrogen fertilizer should be reduced. In addition to sawdust, a soil mulch of bark or rotten tree bark will give the same results as sawdust. Other organic materials such as straw and leaf mulch need to be accompanied by an increase in the amount of nitrogen fertilizer applied. If manure or pen fertilizer is applied, it is not as effective as sawdust and has the side effect of increasing the pH of the soil. Mulching with black plastic mulch is more effective than mulching with sawdust alone.
Applying black plastic mulch prevents soil moisture from evaporating, controls weeds, and increases ground temperature. If sawdust mulching and black mulch mulching are done at the same time, the effect will be better. However, if fertilizer is applied at the same time when covering black plastic mulch, it will cause tree burns, so in production, first apply 925 kg/ha of complete fertilizer, wait for the fertilizer to decompose after 2 years, and then cover black plastic mulch. The disadvantages of applying black plastic mulch are that it is not possible to apply fertilizer, it is inconvenient to irrigate, and it is necessary to re-cover and remove field debris every 2-3 years. Therefore, black plastic mulch is best applied in blueberry orchards with drip irrigation facilities, especially for young blueberry orchards.
Fertilization
1. Nutritional Characteristics
Blueberry is a typical calcium-susceptible plant, which has the ability to absorb and accumulate calcium rapidly. When cultivated in calcareous soil, it often leads to calcium deficiency chlorosis due to high calcium absorption.
Analyzed from the whole tree nutrition level, blueberry belongs to oligonutrient plants, compared with other kinds of fruit trees, the tree body nitrogen, phosphorus, potassium, calcium, magnesium content is very low. Due to this characteristic, too much fertilization often leads to excessive fertilizer and cause tree injury.
Blueberry is like ammonium nitrogen fruit tree, it is ammonium nitrogen in the soil than nitrate nitrogen has a strong absorption capacity.
2. Soil Fertilization Reaction
(1) Nitrogen Fertilizer
The Meden blueberry cultivated on the dark brown forest soil in Changbai Mountain area of China, with the increase of nitrogen application, the yield gradually decreases, the weight of 100 fruits decreases, the fruit ripening is delayed, and the overwintering drawback is serious.
Therefore, when soil fertility is high, nitrogen fertilization is ineffective and harmful to blueberry yield increase, and even causes plant death when too much nitrogen is applied. But this does not mean that in any case, blueberries do not apply nitrogen fertilizer. The University of Minnesota study showed that in the northern experiment station, nitrogen fertilization reduces the yield, while in the Kenkas farm but significantly increased the yield.
In the following cases, blueberries need to increase the application of nitrogen fertilizer: ① Cultivate blueberries on sandy and sandy soils with poor soil fertility and low organic content. ② Cultivating blueberries for many years, when soil fertility declines. ③ When the soil pH is high (>5.5). A total of two applications: 1/2 before budding, and 1/2 after 4 weeks.
(2) Phosphorus Fertilizer
Water wetland submerged soil type of soil is often deficient in phosphorus, increase the effect of phosphorus fertilizer is significant, can promote the growth of blueberry trees, obviously increase the yield. However, when the soil phosphorus content is high, additional phosphorus fertilizer not only can not improve yield, and delay fruit maturity. Generally when the soil contains quick-acting phosphorus is less than 6 kg / ha, it is necessary to increase the application of phosphorus fertilizer 15-45 kg / ha.
(3) Potassium Fertilizer
Potassium fertilizer on blueberry yield effect is significant, increase the application of potassium fertilizer can not only improve blueberry yield, but also make it earlier ripening, improve the quality, enhance the cold resistance. However, excessive potash fertilizer has no effect on the increase of yield, and makes the fruit smaller, the overwintering damage is serious, resulting in magnesium deficiency and other situations. On most berry patch soils where blueberries are cultivated, the appropriate rate of potassium use is 40 kg/ha.
Fertilizer type, mode, period and amount of fertilization
(1) Types
In blueberry fertilization, the use of complete fertilizers is much more effective than fertilizers alone, resulting in a 40% increase in yield. Nitrogen alone on rabbiteye blueberries reduced yields by 40% in 6 years. Complete fertilizers should be the mainstay of blueberry fertilization. Ammonium nitrogen is readily absorbed by blueberries, while nitrate nitrogen is not only not readily absorbed, but also adversely affects blueberry growth. For blueberries, the most recommended ammonium nitrogen fertilizer is (NH4)2SO4. soil application of (NH4)2SO4 not only supply blueberries with ammonium nitrogen, but also has the effect of lowering the pH value of the soil, in the pH value of the higher mineral soil and calcareous soil is particularly suitable.
(2) Method and period
Blueberry fertilization is mainly spreading. Highbush blueberries and rabbiteye blueberries can be applied in furrows, but the depth should be appropriate, generally 10-15 cm. Soil fertilization is generally carried out in early spring before budding, or the second time after budding if it is applied in stages. Fertilizer application to blueberries divided into two or more applications can significantly increase yield and single fruit weight than a single application and is recommended. Split application of fertilizer is generally divided into two times, 1/2 of the total amount applied before budding, and another 1/2 after budding, with an interval of 4-6 weeks between the two times.
(3) Fertilizer application amount
Blueberries are sensitive to fertilization, and over-fertilization can easily cause yield reduction, growth inhibition, plant damage or even death. Therefore, the amount of fertilizer must be careful, can not be determined by experience, but depending on the soil fertility and tree nutritional status to determine.
Water Management
The characteristics of blueberries in terms of water can be summarized as drought resistance, water-loving, fear of flooding. Blueberry drought resistance is strong, but because of the shallow root system, excessive drought will affect its growth, therefore, adequate water is very important for blueberry. However, too much water can also cause blueberry root rot. If the weather is sunny in summer, irrigate every one or two days.
1. Soil moisture content
Proper soil moisture is necessary for blueberry growth, and insufficient moisture will seriously affect tree growth and development and yield. From budding to leaf drop, blueberries need water equivalent to an average of 25 millimeters of precipitation per week, and 40 millimeters from fruiting to fruit harvest. Sandy soils have low soil moisture and low water-holding capacity, and irrigation facilities need to be configured to meet blueberry water needs. Commonly used irrigation methods are furrow irrigation, sprinkler irrigation, drip irrigation and rely on the soil water table to maintain soil moisture in the lower soil irrigation methods.
2. Irrigation time
Irrigation must be carried out before wilting occurs in the plant. The frequency of irrigation should be determined depending on the soil type. Sandy soil water holding capacity is weak, easy to drought, need to frequently check and irrigation; high organic matter content of the soil water holding capacity is strong, irrigation can be appropriately reduced, but in this type of soil, black humus sometimes seem to be wet, but in fact, has been drought, prone to errors in judgment, need special attention. Judging whether to irrigate or not can be based on field experience; take a soil sample at a certain depth and then put it into your hand and squeeze it, if water comes out of the soil then it proves that the moisture is appropriate, if no water comes out of the squeeze, it means that it has been dry. A rough judgment can also be made based on the monthly precipitation during the growing season and the precipitation needed for blueberry growth. When precipitation is 2.5-5 millimeters below normal, a blueberry drought may be caused and irrigation is needed. A more accurate method is to determine the soil moisture content, soil moisture, or soil conductivity and resistance. The method of measurement is relatively simple and accurate. From the field to take 15-45 mm deep soil samples, connected to the resistance meter, when the soil loss of water drought resistance value rises.
3. Groundwater level
Blueberry main production areas or wild distribution areas are mainly located in the sandy organic soil area with underground perched water. Such a soil water table must reach a sufficient height in order to make the upper layer of organic matter sandy soil layer has enough soil moisture. To achieve both good drainage during the rainy season and upper soil moisture, the soil water table should be 45-60 cm. A permanent observation well should be set up in the center of the blueberry orchard to monitor the soil water level.
4. Sprinkler irrigation system
Fixed or mobile judge system is a common method of blueberry irrigation. Sprinkler irrigation is characterized by its ability to prevent or mitigate frost damage. In the new blueberry garden, the newly planted seedlings have not yet developed, the root system absorption capacity is poor, the most suitable method of sprinkler irrigation. In the United States blueberry large production areas, often using high-pressure spray gun for sprinkler irrigation.
5. Drip irrigation system
Drip irrigation and micro-sprinkler irrigation in recent years more and more applications. These two irrigation methods require medium investment costs, but the water supply for a long time, high water utilization, supply of water directly to each tree, less water loss, less evaporation, water supply uniformity and consistency, and once opened can be a long-term supply in the growing season. It requires little mechanical power and is well suited for use in small area cultivation or yard cultivation. Compared with other methods, drip irrigation and micro-sprinkler irrigation can better maintain soil moisture without drought.
6. Water source and quality
The more desirable water sources are surface pond water and reservoir water. Deep wells tend to have high pH and high Na+ and Ca+ content, which will affect the growth and yield of blueberries if used for a long time. When cultivating blueberries in the Changbai Mountain region of China, natural precipitation can basically meet the requirements of blueberry growth and results due to the large annual precipitation in the region and its uniform distribution. However, irrigation facilities should be prepared when possible.
Shade
According to the study of blueberry photosynthesis by Yadong Li et al, blueberry has a low light saturation point compared to other fruit tree species. Strong light has an inhibitory effect on blueberry growth and fruiting. In northern China, on sunny days of the Spring Festival every year, blueberry leaves wilt or even scorch due to strong light. Therefore, in areas with open terrain and strong light, cultivation with shade is recommended. Shade netting above the tree rows is a practical technique that has been widely promoted in recent years in Chile.
The use of shade netting above the tree rows is a practical technology that has been widely popularized in recent years in Chile. Shade nets are usually placed directly above the rows of trees, and another type is placed directly above the rows (so that the tree receives more light).
The functions of shade nets are very obvious and diversified, specifically the following.
① Delayed ripening: This is the most important function of sunshade netting (set during the flowering period), which can generally delay fruit ripening by more than 7 days, especially for late-maturing varieties, which can extend the supply period of fresh fruits.
② decentralized ripening: shade net can make the fruit ripening process delayed. The same tree and fruit ripening on the spike dispersed, the staging of batch harvesting is favorable.
③Enhance the growth potential of the tree, increase the hardness of the fruit, so as to improve the fruit’s ability to resist storage and transportation.
④ It has the function of frost prevention.
Winterization against cold
Although the dwarf bush blueberry and half-high bush blueberry are more resistant to cold, but affected by different degrees of low temperature, there are still frost damage occurs, of which the two most important to the frost damage is overwintering twitching and flower buds frost damage. In special years, the severe winter cold makes the above ground part all frozen. Therefore, in cold regions, the overwintering protection of blueberry cultivation is also an important measure to improve the yield. In the northern cold regions, winter snow is big and thick, you can use this natural advantage of artificial snow, to ensure the safety of the tree overwintering, compared with other methods, artificial snow has a convenient material, labor-saving, time-saving, less expensive and other characteristics, and after the pile of snow can keep the tree body with sufficient moisture, so that the blueberry yield is greatly improved than not cold-proof, compared with the cover of leaves, straw, the yield is also significantly higher. In the southern cold areas, the tree covered with straw, leaves, plastic mulch, sack sheets, straw woven bags, etc. can play a role in overwintering protection.
Post time: May-06-2025