Table of Contents

Chapter 1 General ……………………………………………………………… 1

Section 1 Economic Significance of Pear Cultivation ………………………… 1

Section 2 History and Current Situation of Pear Cultivation ………………… 1

Section 3 Problems and Developing Trends in Pear Production ……………… 2

Chapter 2 Superior Cultivars ………………………………………………… 5

Section 1 Classification of Pears Cultivated in China ………………………… 5

Section 2 Superior Cultivars ………………………………………………… 6

Section 3 Cultivar Selection ………………………………………………… 25

Chapter 3 Growth and Fruiting Habits …………………………………… 27

Section 1 Characteristics of Roots ………………………………………… 27

Section 2 Characteristics of Buds, Branches, and Leaves ………………… 34

Section 3 Flower Bud Diff erentiation ……………………………………… 44

Section 4 Flowering and Fruiting ………………………………………… 46

Section 5 Development of Fruits …………………………………………… 48

Section 6 Requirements for Environmental Conditions …………………… 49

Chapter 4 Nursery Techniques …………………………………………… 53

Section 1 Types and Selection of Rootstock ……………………………… 53

Section 2 Nursery Techniques …………………………………………… 56

Section 3 Breeding of Dwarfing and Virus-free Seedlings ………………… 69

Section 4 Top Grafting for Growing Superior Cultivars …………………… 70

Chapter 5 Orchard Construction Techniques …………………………… 73

Section 1 Selections of Orchard Land ……………………………………… 73

Section 2 Orchard Planning and Setting …………………………………… 77

Section 3 Planting of Pear ………………………………………………… 84

Chapter 6 Nutrient, Soil, Fertilizer, and Water Management Techniques

for Pear Trees ………………………………………………… 89

Section 1 Nutrient Elements for Pear Trees ………………………………… 89

Section 2 Soil Management Techniques for Pear Orchard ………………… 95

Section 3 Fertilizer Requirement Characteristics of Pear Trees and

Scientific Fertilization …………………………………………… 121

Section 4 Irrigation and Drainage ………………………………………… 147

Chapter 7 Trimming and Pruning of Pear Trees ………………………… 152

Section 1 The Principle and Function of Trimming and Pruning of

Pear Trees ………………………………………………………… 152

Section 2 The Basis, Time, and Method of Trimming and Pruning for

Pear Trees ………………………………………………………… 158

Section 3 Trimming Characteristics of Pear Trees and Requirement for

High-yield Tree Shapes ………………………………………… 169

Section 4 Main Tree Shapes of Pear Trees ………………………………… 173

Section 5 Method of Pruning ……………………………………………… 180

Section 6 Innovation of Trimming and Pruning Technology for Pear Trees … 184

Chapter 8 Flower and Fruit Management ………………………………… 188

Section 1 Pollination Promotion and Fruit Setting Rate Improvement …… 188

Section 2 Frost Prevention during Anthesis ………………………………… 190

Section 3 Blossom and Fruit Thinning …………………………………… 191

Section 4 Fruit Bagging …………………………………………………… 194

Section 5 Harvesting, Packaging, and Transport of Fruits ………………… 196

Chapter 9 Top Grafting for Growing Superior Cultivars ………………… 200

Section 1 Top Grafting Period ……………………………………………… 200

Section 2 Treatment of Top Grafting Trees ………………………………… 200

Section 3 Grafting ………………………………………………………… 201

Section 4 Post-grafting Management ……………………………………… 201

Chapter 10 Integrated Control Technology for Diseases and Pests

on Pear Trees ………………………………………………… 203

Section 1 Occurrence and Infection of Diseases on Fruit Trees …………… 203

Section 2 Identification and Retrieval of Fruit Tree Diseases ……………… 214

Section 3 Identification of Fruit Tree Pests ………………………………… 226

Section 4 Scientific Control Technology for Diseases and Pests

on Fruit Trees …………………………………………………… 230

Section 5 Pear Diseases and Control ……………………………………… 256

Section 6 Pear Pests and Control …………………………………………… 274

Section 7 Physiological Diseases of Pear Trees …………………………… 315

Appendixes …………………………………………………………………… 325

References …………………………………………………………………… 352

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Abstract
VII. Problems of Fertilization in Pear Orchards and Methods of Improving Fertilizer Efficiency 1. Problems of Fertilization in Pear Orchards (1) Excessive use of chemical fertilizer. Fruit farmers do not know the soil nutrient status of orchards, so they often blindly apply fertilizers based on their experience and habits, believing that the more fertilizers are applied, the better. This phenomenon particularly occurs in the use of nitrogen fertilizer, which often causes a strong preference for nitrogen fertilizer, resulting in vigorous growth of trees and degradation of fruit quality. (2) Less use of base fertilizer. The land conditions of most orchards in China are relatively poor, and most orchards have severely insufficient organic matter in the soil. The application of base fertilizer in autumn is crucial to the quality of fruit, but many orchards do not apply base fertilizer or apply insufficient base fertilizer. 2. Methods of Improving Fertilizer Efficiency (1) Fertilization according to the life cycle. ① In the sapling stage, sufficient nitrogen and phosphate fertilizers and an appropriate amount of potassium fertilizer should be applied in order to expand the canopy, allow the tree body to grow well, and expand the root system. ② In the early fruit-bearing stage, phosphate fertilizer should be increased in combination with nitrogen and potassium fertilizers to promote flower bud diff erentiation and improve yield rapidly. ③ In the full bearing stage, nitrogen, phosphate, and potassium fertilizers should be applied together with the properly increased proportion of nitrogen fertilizer, so as to achieve high quality, high yield, and stable yield. ④ In the senescence stage, nitrogen fertilizer is mainly used in proper combination with phosphate and potassium fertilizers to renew, rejuvenate, and prolong the lifespan. (2) According to the soil and leaf analysis, fertilizer is applied according to the fertilizer prescription once every two years, which is determined to be a more scientific fertilization method at present according to the measured data and the corresponding parameters of the high-yield orchard. (3) More organic fertilizer should be applied during deep plowing in autumn. Human excreta, barnyard manure, compost, farmyard fertilizer, cake manure, straw manure, etc. can increase the content of organic matter in the soil, which is beneficial to microbial activities. (4) Foliage dressing is generally carried out in spring. Depending on the deficient nutrients, nitrogen, zinc, boron, ferrum, calcium, etc., should be supplemented, which are easy to absorb and apply, with rapid fertilizer efficiency. This can also be carried out in combination with spraying. VIII. Symptoms and Treatment of Element Deficiency in Pear Trees 1. Nitrogen (1) Symptoms of nitrogen deficiency: For the diagnosis of nitrogen deficiency, mature leaves from spring shoots grown in the current year are taken for analysis. When the nitrogen content of leaves is less than 1.8%, it is deemed deficient; When the nitrogen content is 2.3%-2.7%, it is deemed appropriate; When the content is more than 3.5%, it is deemed excessive. When pear trees are deficient in nitrogen, old leaves in the lower part at the early stage will fade, new leaves will grow smaller, and shoots will grow weakly. In the case of severe nitrogen deficiency, the leaves of the whole tree will fade evenly in diff erent degrees, showing light green to yellow, and the old leaves will turn red and fall in advance; The shoots become aging, with fewer fl ower buds generated; Leaves will fall early, with fewer flower buds, flowers, and fruits, and fruits are small but in good color. Insuff icient nutrients of pear trees stored in the past year and less fertilizer or untimely fertilization during the growing season may cause nitrogen deficiency in shoots and fruits at the vigorous growth stage. (2) In the treatment of nitrogen deficiency, the application of nitrogen fertilizer can be effective. As a source of nitrogen, urea can be used for foliar feeding. However, attention should be paid to selecting urea with low biuret content to avoid spray injury. 2. Phosphorus (1) Symptoms of phosphorus deficiency. The analysis results show that the available phosphorus content ranges from 0.05% to 0.55%, with 0.14% as the optimal value. Pear trees show no obvious symptoms at the early stage of phosphorus deficiency. At the middle and late stages of phosphorus deficiency, the growth and development of plants are hindered. When the leaf turns dark yellowish brown, indicating symptoms of severe phosphorus deficiency, leaves grow slowly and become smaller and sparse, with withered edges and poor resistance. The leaves turn dark yellowish-brown to purple, without luster, and fall early, with short shoots. In the case of severe phosphorus deficiency, the edge and apex of leaves are withered, the flowers, fruits, and seeds are reduced, the anthesis and maturity periods are delayed, and the fruit yield is low. Common phosphorus-deficient soil includes highly weathered and organic matter-deficient soil as well as dry soil at low temperatures for a long time, which aff ects the diff usion and absorption of phosphorus; Pear trees applied with excessive nitrogen fertilizer and insufficient phosphate fertilizer are prone to showing symptoms of phosphorus deficiency. (2) Treatment: The barnyard manure contains long-lasting available phosphorus, which can be applied in various seasons. In the foliar feeding, 0.1%- 0.3% potassium dihydrogen phosphate, monoammonium phosphate, or calcium superphosphate leaching solution can be used. 3. Potassium (1) Symptoms of potassium deficiency: When the total potassium content of the mature leaf of the spring vegetative shoot of pear tree is less than 0.7%, it is deemed deficient, and when such content is 1.2%-2.0%, it is deemed appropriate. At the early stage of potassium deficiency of pear trees, the apex and edge of the old leaves are fading, and shoots become slender and grow poorly, with poor resistance. At the middle stage of potassium deficiency, the apex and edge of the lower mature leaves are gradually withered inward, showing dark brown or black burns, and the whole leaf is curled or shrunk in a cup shape. In the case of severe potassium deficiency, mature leaves and leaf edges are withered; The whole leaf is dry, does not fall off , and is retained on the shoot; Edges of new leaf grown on the shoot are withered until the plant dies. When the soil is dry, the mobility of potassium is poor; When the soil is waterlogged, the root vitality is low, and the absorption of potassium is blocked; When the tree body is overloaded continuously, and the soil lacks potassium, the plant is prone to potassium deficiency. (2) Treatment: The potassium deficiency can be treated by applying potassium fertilizers such as potassium chloride and potassium sulfate in the soil. Spraying sufficient brine solution containing potassium can also achieve a good treatment effect. The spraying method is to apply potassium sulfate, potassium chloride, plant ash, and other potassium fertilizers in the ditch during the fruit expansion stage and flower bud differentiation stage. During the growing season from May to September, 0.2%-0.3% potassium dihydrogen phosphate or 0.3%-0.5% potassium sulfate solution can be applied in combination with spraying for foliage top dressing, generally 3-5 times. 4. Calcium (1) Symptoms of calcium deficiency: When the total calcium content of the intact leaves in the middle of the current-year shoots of pear trees is less than 0.8%, it is deemed deficient; The total calcium content of 1.5%-2.2% is an appropriate range. At the early stage of calcium deficiency, the young tender parts are stunted, the new leaves are difficult to develop, and the tender apex and edges are adhered, twisted, and malformed. In the case of severe calcium deficiency, the terminal bud is withered, and spots or necrotic patches appear on the leaves. The epidermis of young fruits is suberized, and necrotic lesions appear on the surface of mature fruits. In most cases, symptoms of calcium deficiency will not appear on the leaves but appear on the fruit, resulting in various physiological disorders, for example, bitter pit, splitting fruit, soft cork disease, stony pit, pulp necrosis, heart rot, water core, etc. Calcium deficiency easily occurs in such soils developed from acid igneous rock and bertholite, as well as sandy soil in high rainfall zones. Calcium deficiency easily occurs in pear trees when less organic fertilizer is applied, sandy soil lacks organic matter and the soil has a poor capacity to absorb and preserve calcium. The application of lime (calcium hydroxide) generally can treat calcium deficiency in acidic soil. If the soil only lacks calcium, the application of gypsum, calcium nitrate, and calcium chloride can achieve the desired result. (2) Treatment: 0.3%-0.5% calcium nitrate solution can be sprayed on the canopy of the tree from 4-6 weeks after blossom drop to 3 weeks before harvesting, 3-4 times continuously, once every 15 days