Cultivation techniques of pear trees

Pear trees are widely distributed, so their phenological periods are very different. As far as flowering period is concerned, Huili and pear trees in Sichuan generally bloom in the first half of February, and Yanbian in Jilin blooms in mid-May. Yali pear bloomed in Changsha, Hunan Province in early March and in Beizhen, Liaoning Province in early May, with a difference of nearly two months. Pear trees cultivated in the same area have different phenological periods due to different species and varieties. From germination to flowering, pear is the earliest, pear is a little later, sand pear is later than pear, and western pear is the latest, with a variation range of about 10 day.

Flowering management

The flowering management of pear trees is very important. If the flowering period of pear trees is not properly managed or left unchecked, it will easily lead to the phenomenon of full flowers and half fruits, low fruit setting rate and low economic benefits. Adopting the following methods to strengthen the management of pear flowering period can improve the fruit setting rate, fruit quality and economic benefits.

Topdressing before flowering: Topdressing before flowering can improve the quality of flower buds, meet the nutrition consumed by flowering and improve the fruit setting rate. Quick-acting fertilizer, mainly compound fertilizer, can be applied in the first half of the flower. Generally, 0.5- 1 kg is applied to each adult tree, and 1-2 kg of urea can be added to weak trees, and the fertilizer application amount should account for 10- 15% of the whole year.

Pruning before flowering: pear trees with light pruning and large flowers should be pruned again, mainly to remove weak branches, diseased dead branches and over-dense branches, adjust the load of fruit trees, and determine the amount of flowers according to the amount of fruits left. Generally, the amount of flowers left is 65,438+0-2 times more than the amount of fruits left, and only 65,438+0 flower buds are left on each fruit table to remove redundant flower buds, which is responsive to pruning.

Flower thinning and artificial pollination: pear flower buds are compound buds, with as many as 5- 18 flowers per inflorescence. Flowering consumes a lot of nutrients in the tree, which can make the nutrient supply of the tree centralized and improve the fruit setting rate. When the inflorescences are separated, the flowers can be thinned, and each inflorescence has 1-2 flowers. For varieties with low self-pollination rate, pollination trees should be arranged. If pollinated varieties are not arranged, artificial pollination shall be carried out. During artificial pollination, fully developed buds or newly opened flowers should be collected from adult trees of suitable pollination varieties 2-3 days before pollination, and anthers should be taken, dried in the sun to make powder, and manpower should be concentrated for artificial point feeding in full bloom.

Spraying boron at flowering stage: boron can promote the germination and elongation of pollen tubes and promote the transport of sugar in trees. Spraying boron at flowering stage can improve the fruit setting rate of pear trees. When flowering is 25% and 75%, 0.3-0.5% borax (acid) solution and 0.3-0.5% urea can be sprayed 1 time respectively, which requires a lot of phosphorus and potassium elements for flowering.

Frost prevention in flowering period: pear trees bloom early, mostly before late frost, and are easily affected by late frost. After the pear flower is frozen, the male and female stamens turn brown, dry and shrink, and cannot bear fruit. There are several ways to prevent frosting:

1. Irrigation before flowering can reduce ground temperature, delay root activity, delay flowering, and reduce or avoid the harm of late frost.

2. Painting the trunk white before flowering can make the temperature of the tree slowly rise and delay flowering for 3-5 days, thus avoiding or alleviating the freezing injury.

3. Smoking prevents frost. Smoking can reduce the radiation of soil heat and play a role in moisturizing. At the same time, smoke particles can absorb water, make water vapor condense into liquid and release heat, increase ground temperature and reduce or avoid freezing injury. The flowering period depends on the local weather forecast. When the temperature is likely to drop to -2℃, it is necessary to prevent frost. Commonly used smoking materials are sawdust, straw, firewood and leaves, which are stacked layer by layer and staggered, with kindling inserted in the middle, which is convenient for igniting smoke. Before smoking, you must organize personnel to be on duty, hang a thermometer at a distance of 1 m from the ground, and record the temperature regularly. If the temperature suddenly drops to 0℃ in the morning, it is necessary to ignite and smoke. You can also use anti-frost smoke agent to prevent frost. The commonly used formula is ammonium nitrate 20-30%, sawdust 50-60%, waste diesel oil 10% and pulverized coal 10%. The finer ammonium nitrate, sawdust and pulverized coal, the better. Mix in proportion, put in iron drums, and ignite when using, with the dosage of 2-2.5 kg per mu.

Eliminate pests and diseases

1. Pear rot mainly damages the bark of main branches and lateral branches, causing rot. There are two kinds of symptoms: ulcer type and dead branch type. In severe cases, a large number of dead branches appear until death. It is necessary to strengthen orchard management, control fruit setting, improve the disease resistance of trees, and select disease-resistant varieties. Cut off diseased branches and scars in time, burn them centrally, and apply thiram wettable powder 30 ~ 60 times. Spraying 40% thiram-arsenic wettable powder 100 times or puti 100 times, or Pomei's 5-degree stone sulfur mixture on pear trees before germination.

Second, pear black spot disease is a common and frequently-occurring disease of pear trees, which mainly harms fruits, leaves and new shoots. In general, leaf spot disease appears in Liaoning Province from late April to early May, with an average temperature of 65,438 03℃ to 65,438 05℃, and the most serious disease occurs in May and June. However, the fruit usually starts to get sick in early May, cracks and falls off in mid-June, and the fruit falls off most in late July. The key point of prevention and control is to strengthen cultivation management, increase application of organic fertilizer and avoid partial application of nitrogen fertilizer. Combined with winter pruning, remove dead branches, fallen leaves and diseased fruits in the garden and bury them deeply. In seriously ill orchards, the mixed solution of 0.3% sodium pentachlorophenol and 5Be sulfur mixture was sprayed before the trees germinated, and Bordeaux solution with 200 times lime volume, or 50% amobam 1000 times solution, 10% polycyclic serine wettable powder 1000+ was sprayed. Alternating use of the above chemicals with Bordeaux mixture can improve the control effect and reduce the cost.

3. Dendrolimus punctatus is the main leaf-eating pest of pear trees, which damages flower buds, buds and leaves with larvae. It can happen twice a year, usually once in March-April and once in August-September. When the overwintering larvae emerge from the sting, it is the suitable period for control, that is, the period from flower bud to inflorescence separation of pear trees. Commonly used pesticides are: 50% parathion emulsion 1500 times, 50% phoxim emulsion 1000 times, 50% fenitrothion emulsion 1000 times, 50% malathion emulsion 1000 times, and 50% dichlorvos emulsion/.

Four, pear real peak (commonly known as flower diamond, white diamond worm) is only harmful to pear trees. Adults lay eggs in the calyx, and larvae first feed on the inner ring at the base of the calyx. After being blackened, they eat into the core of the fruit, making the young fruit dry and fall off. The larva crawls out before the fruit falls, endangering other young fruits. The insect has one generation a year and overwinters in the soil with mature larvae as cocoons. Adults emerge and lay eggs from late April to early May, and the peak of laying eggs is when the inflorescence of pear tree is separated until the petals appear, and the larvae eat fruit in the middle and late May.

During the prevention and control, the adults can be suspended in suspended animation, and a piece of cloth can be lifted under the canopy to shake off the adults and kill them, or the eggs, flowers and young fruits with insects can be artificially removed during the spawning period. Before pear blossom 10 ~ 15 days, when adults are unearthed, spray 25% parathion 300 times solution, 25% phoxim 300 times solution or 40.7% dimethoate 600 times solution on the ground, focusing on trunk circumference 1 m.

Prevention and control of early defoliation

The premature defoliation of pear trees will cause a serious shortage of storage nutrition, reduce the cold resistance of fruit trees, affect the late differentiation of flower buds and flowering and fruiting in the following year, make a large number of fruits deformed and dropped, and seriously affect the yield and quality of fruits.

1. Spray Bordeaux. Spraying Bordeaux solution to prevent diseases during fruit expansion period can not only prevent rain erosion, but also supplement copper and calcium elements for pear leaves, so that pear trees grow vigorously, leaves are dark green and plump, and early deciduous leaves are reduced.

Second, strengthen water and fertilizer management. Pear trees need adequate nutrition supply when they enter the fruit expansion stage and flower bud differentiation stage. Before and after the wheat harvest, the precipitation was less, and the high temperature and dry weather seriously affected the water supply of trees. At this time, it is necessary to strengthen water and fertilizer management in time. First, it is necessary to topdressing potassium sulfate compound fertilizer with high nitrogen, medium phosphorus and high potassium in time, and water it properly after topdressing to prevent flooding and root retting. Secondly, spraying potassium nitrate compound fertilizer, potassium dihydrogen phosphate and Yongye life essence on the leaves with quick effect, less loss and quick absorption can promote pear leaves to be large, thick, green and bright, and reduce deciduous leaves. Third, control the use of organophosphorus pesticides. Organophosphorus pesticides can stimulate the leaves of pear trees, especially when the concentration is too high, the application times are too many and the application time is in the high temperature period, which will cause a large number of fallen leaves of pear trees. Therefore, the frequency and concentration of organophosphorus pesticides must be strictly controlled. If other pesticides can be used instead, it is best to use biological pesticides or pyrethroid pesticides instead. When it is necessary to use them, attention should be paid to the concentration. Spraying time should be before 10 in the morning and after 4 pm, avoiding the high temperature period at noon.

Pruning method

To prune pear trees scientifically, we must master these principles. That is, "tangible immortality, intangible chaos, because the tree prunes, follow the tree", "overall planning, long-term planning, balance the tree potential, clear affiliation", "light foundation, light combination, flexible grasp", "restrain the strong and help the weak, correctly promote control, rationally use the light, and strengthen the branches" It should be conducive to strong trees, early fruiting, high and stable yield, high quality fruit, long-term economic benefits of pear orchards and adaptation to local environmental conditions. On the basis of the above principles, we must also rely on the following factors, that is, to achieve the "five basics" in order to play its due pruning role.

According to the characteristics of varieties

Different varieties have different growth and fruiting habits and different pruning methods. For example, Korean pear varieties such as Gold, Crystal, Gaoxin, Huangyuan, Huashan, Nanshui, Huang Xian and Qiuhuang. There are many axillary flower buds in the young tree stage. When pruning, the method of short cutting should be adopted to promote the development of new shoots, so as to form a large number of branches and leaves as soon as possible and improve the yield. The flower buds of Xiyang pear are mostly on the terminal buds, which bear fruit early and form a larger tree structure as soon as possible. When pruning, we should reduce short segments and leave more terminal buds to bear fruit. New pear varieties in China are not easy to form axillary buds, such as emerald, July crisp and agate. , mainly short branches. When pruning, release it slowly to form more flower buds as soon as possible. After the results, the branches except the extended branches should be retracted in time to prevent the bearing part from moving out, resulting in empty lumen and decreased yield in the later stage. According to the age and potential of trees

The pruning of young pear trees should be light and long, and technical measures such as multi-line branch pulling, coring, slow release and short cutting should be adopted, and thinning should be used less. After entering the fruiting period, pruning methods such as drying and retraction are mostly used, and slow release and branch pulling are less used. In order to prolong the fruiting period, the pruning method of retraction and renewal should be adopted to restore the tree potential. Trees with great potential can be stripped, cut less and sparse more; If the tree is weak, technical means such as short cutting and retraction should be used more, and cutting methods such as slow release and thinning should be used less. Judging the strength of a tree depends on the annual growth and robustness, the number and length of summer shoots, and the fullness of buds. Trees with strong tree vigor generally have large and full buds, bright colors, thick branches, bright colors, large and prominent lenticels, and small and full pith in the middle, which is a manifestation of strong tree vigor. Weak trees are characterized by weak and thin branches, small and shriveled buds, thin skin and short new shoots. This is the performance of the weak tree.

According to soil fertility and environmental conditions

In plots with good soil fertility, trees are generally strong and need to be pruned slowly. The so-called "slow pruning" means to slow down the growth rate of trees by pruning, that is, more technical measures such as pulling branches, slow release, thinning branches, girdling, girdling, eye injury, coring and twisting are adopted. In the plots with poor soil fertility, the tree potential is generally weak, so pruning should be used more. The so-called "promoting pruning" means to adopt pruning methods to promote the growth of trees, that is, to use more methods such as short pruning, less pruning, slow release and slow pruning. Generally, plots with good soil fertility have higher stems, preferably 70~80cm, fewer main branches and larger interlayer spacing, generally in the range of 80~ 100cm. Generally, plots with poor soil fertility should be set at a lower level, preferably 50~60cm, and the spacing between layers should be smaller, generally within the range of 50~60cm. In addition, the pruning method should be determined by considering climate, density, rootstock, pest control and other conditions. For example, in Jiaodong, Shandong, half of the year is damaged by late frost, so the pruning of young trees must keep the back branches and cultivate them into small fruiting branches, even if they are not used for fruiting. Because according to our investigation for many years, late frost usually occurs in late April, and young fruits under leaves are rarely frozen. Under the same conditions, when pruning, keep the branches on the back and cut them again. Generally, 2~3 branches are produced in the next year, and the leaves are large and thick, which better protects the lower fruits from the harm of late frost.

According to pruning reaction

Pruning reaction is an important basis for fruit tree pruning, and it is also one of the important criteria to judge whether pruning is correct. Pruning reaction is generally viewed from two aspects. One is local reaction, that is, after a branch is cut short or retracted, the performance of germination, branching, fruiting and flower bud formation is seen under the incision, which is local reaction. The second is to look at the overall reaction. After pruning, look at the total growth of the whole tree, the length of new shoots, the maturity and density of branches, the number of flower buds formed, and the yield and quality of fruits. This is the overall reaction. According to the pruning reaction, the pruning method, technical measures and pruning degree are defined so as to carry out correct pruning.

According to the management level

The shaping and pruning of pear trees must be combined with the management level, and the role of shaping and pruning can be well reflected in a well-managed pear garden. Different cultivation modes need different methods of shaping and pruning, and the degree of pruning is also different. For example, close planting garden needs smaller crown diameter and shorter crown diameter, while sparse planting garden needs larger crown diameter and larger crown diameter. In a word, as long as different shaping and pruning are carried out according to different situations, better results will be achieved.