When do pear trees sprout in Changzhi area of Shanxi Province?
The germination time depends on the local climate. In the Changzhi area of Shanxi, about half a month before Qingming Festival, the flowers bloom first and then grow leaves.
Phenological phase
Pear trees have a wide distribution range, so their phenological phases vary greatly. In terms of flowering period, pear trees generally bloom in early to mid-February in Huili, Sichuan, and mid-May in Yanbian, Jilin; Yali trees bloom in early March in Changsha, Hunan, and early May in Beizhen, Liaoning. The flowering periods vary from place to place. nearly two months. Pear trees cultivated in the same area have different phenological stages due to different types and varieties. From bud germination to flowering, the Qiuzi pear variety is the earliest, the white pear variety is later, the sand pear variety is later than the white pear variety, and the Western pear variety is later. is the latest, and the range of changes is about 10 days.
Management during the flowering period
Management during the flowering period of pear trees is very important. Only when there are flowers can there be fruits. Improper management of the flowering period of pear trees, or if they are left alone, can easily lead to the phenomenon of a tree full of flowers and half a tree full of fruits. , the fruit setting rate is low and the economic benefits are low. Using the following methods to strengthen the management of pear trees during the flowering period can increase the fruit setting rate, improve fruit quality, and improve economic benefits.
Top-dressing before flowering: Top-dressing before flowering can improve the quality of flower buds, meet the nutrients consumed by flowering, and increase the fruit setting rate. Quick-acting fertilizers, mainly compound fertilizers, can be applied half a month before flowering. Generally, 0.5-1 kg per adult tree. For weak trees, 1-2 kg of urea can be added. The amount of fertilizer should account for 10-15% of the year. %.
Re-pruning before flowering: pear trees that are pruned too lightly and retain a lot of flowers should be pruned again, mainly to remove thin and weak branches, diseased and dead branches, and overly dense branches, and to adjust the load of the fruit tree. Determine the amount of flowers left based on the amount of fruit left. Generally, the amount of flowers left should be 1-2 times more than the amount of reserved fruit. Only one flower bud is left on each fruit stand. Excessive flower buds are thinned out. Those who are not sensitive to pruning will not easily grow. The string of flower buds formed by the spreading of growing branches of flower varieties should be shortened appropriately to bring the fruiting branches closer to the main trunk and promote the growth of branches to prepare for future fruiting.
Flower thinning and artificial pollination: Pear tree flower buds are compound buds, with up to 5-18 flowers per inflorescence. Flowering consumes a lot of nutrients in the tree. Thinning out excess flowers can concentrate the nutritional supply of the tree. , to increase the fruit setting rate, you can thin the flowers when the inflorescences are separated, leaving 1-2 edge flowers in each inflorescence. For varieties with low self-fertilization rate, pollination trees should be arranged. If pollination varieties are not arranged, artificial pollination should be carried out. Artificial pollination should be done 2-3 days before pollination by collecting fully enlarged flower buds or flower buds on adult trees of varieties suitable for pollination. The anthers of the flowers that have just opened are collected, dried to produce powder, and manpower is concentrated on artificial seeding during the initial flowering period.
Spray boron during the flowering period: Boron can promote the germination and elongation of pollen tubes and promote the transportation of sugar in the tree. Spraying boron during the flowering period can increase the fruit setting rate of pear trees. It can be used when the flowers bloom at 25% and 75%. Spray 0.3-0.5% borax (acid) solution once each and add 0.3-0.5% urea. Flowering requires a large amount of phosphorus and potassium elements plus spraying or spraying 0.3% potassium dihydrogen phosphate solution alone, which can also increase the fruit setting rate.
Prevent frost during the flowering period: Pear trees bloom early, usually before late frost, and are extremely susceptible to damage from late frost. After pear flowers are frozen, the female stamens turn brown, shrink, and bloom but fail to set fruit. How to prevent frost There are the following types:
1. Irrigation before flowering can lower the ground temperature, delay root activity, delay flowering, and reduce or avoid the damage of late frost.
2. Painting the trunk white before flowering can slowly increase the temperature of the tree and delay the flowering period for 3-5 days, thus avoiding or reducing the damage of frost.
3. Smoke prevents frost. Smoke can reduce the radiation of soil heat and have a moisturizing effect. At the same time, the smoke particles can absorb moisture and condense the water vapor into liquid to release heat, increase the ground temperature and reduce the risk of frost. Or avoid frost damage. You should listen to your local weather forecast during the flowering period. When the temperature is likely to drop to -2°C, it is necessary to prevent frost. Commonly used smoking materials include sawdust, straw, firewood, leaves, etc., stacked in staggered layers, with fire starters inserted in the middle to facilitate ignition and smoke. Before smoking, It is necessary to organize manpower and dedicate people to be on duty, hang a thermometer 1 meter away from the ground, and record the temperature regularly. If the temperature suddenly drops to 0°C in the early morning, the smoke should be ignited. When igniting, the same order should be given at the same time. Pay attention to precautions after ignition. Light the fire and make it emit as much smoke as possible, and be careful not to burn the tree branches. Anti-frost aerosols can also be used to prevent frost. The commonly used formula is 20-30% ammonium nitrate, 50-60% sawdust, 10% waste diesel, and 10% fine coal powder. The finer the ammonium nitrate, sawdust, and coal powder, the better. , after mixing according to the proportion, put it into an iron cylinder and ignite it when used. The dosage per acre is 2-2.5 kilograms, and it should be placed upstream.
Pests and diseases control
1. Pear tree rot mainly damages the bark of main branches and side branches, causing rot. There are two types of symptoms: ulcer type and branch dead type. In severe cases, a large number of dead branches appear until death. During prevention and control, it is necessary to strengthen orchard management, control the amount of fruit set, improve the tree's disease resistance, and select and breed disease-resistant varieties. Cut off diseased branches in time, scrape off disease scars, burn them together, and apply 30 to 60 times of Thiram arsenic wettable powder. Before pear trees sprout, spray 40% Baume arsenic wettable powder 100 times or rotten enemy 100 times liquid, or Baume 5 degree lime sulfur mixture.
2. Pear black spot disease is a common and frequently-occurring disease of pear trees, which mainly damages fruits, leaves and new shoots. In Liaoning Province, leaf spots usually begin to appear from late April to early May, when the average temperature is 13°C to 15°C, and the disease is most severe from May to June. The fruit usually begins to develop symptoms in early May, cracks and falls off in mid-June, and reaches its maximum fruit drop in late July.
The key points of prevention and control are to strengthen cultivation management, increase the application of organic fertilizers, and avoid partial application of nitrogen fertilizers. Combined with winter pruning, remove dead branches, fallen leaves and diseased fruits in the garden and bury them deeply. Spray 0.3% sodium pentachlorophenol plus 5Be lime sulfur mixture on trees in seriously ill gardens before germination. After flowers fall, spray Bordeaux mixture with 200 times the amount of lime, or 50% ammonium 1000 times, or sterilizing special wettability. The powder is 600 to 800 times the liquid, and the 10% polyoxic acid wettable powder is 1000 to 1500 times the liquid, but the application should not be more than 3 times a year. The alternate use of the above-mentioned agents and Bordeaux mixture can improve the control effect and reduce costs.
3. Pear star caterpillar is the main leaf-eating pest of pear trees. Its larvae damage flower buds, buds, and leaves. It can occur twice a year. It is usually controlled once from March to April and once from August to September. . The appropriate period for prevention and control is when the overwintering larvae emerge, from when the pear tree flower buds turn white to when the inflorescence separates. Commonly used agents include: 50% parathion emulsion 1500 times, 50% phoxim emulsion 1000 times, 50% fenitrothion emulsion 1000 times, 50% malathion emulsion 1000 times, 50% dichlorvos emulsion 1000 times liquid and 20% permethrin emulsion 3000 times liquid.
4. Pear Shifeng (commonly known as flower borer, white borer) only harms pear trees. The adults lay eggs in the calyx, and the larvae initially feed in a ring at the base of the calyx. The damaged area turns black and then bores into the core of the fruit, causing the young fruit to dry up and fall off. The larvae crawl out before the fruit falls and cause damage to other young fruits. The insect produces one generation a year, and the mature larvae overwinter in cocoons in the soil. Adults emerge and lay eggs from late April to early May. The peak egg-laying period is when the inflorescences of pear trees are separated and the petals are in bud. In mid-to-late May, the larvae cause fruit damage.
During prevention and control, you can take advantage of the suspended animation of adults, pick up sheets under the canopy, shake off the fallen adults to kill them, or manually remove egg-bearing flowers and fruits and young fruits with insects during the egg-laying period. 10 to 15 days before the pear tree blooms, when the adults emerge and are unearthed, use 25% parathion 300 times, 25% phoxim 300 times, or 40.7% Lesborne EC 600 times for ground spraying, focusing on the trunks. Within 1 meter.
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