Management Methods for Pear Trees in the Late Full-Bearing Stage and the Senescent Stage

Once pear trees enter the late full-bearing stage and the senescent stage, poor management, insufficient fertilizer and water, excessive fruiting load, and worsening pests and diseases will accelerate the trees' decline and death, causing them to lose their cultivation value.

I. Manifestations of pear trees in the late full-bearing stage and the senescent stage

Late full-bearing stage: yield declines year by year, new shoot growth decreases, growth vigor becomes more moderate, and perennial fruiting branch groups weaken year by year, with some parts dying back. The fruiting position shifts outward markedly, scaffold branches droop severely and become bare at the rear, and sometimes water sprouts readily emerge at the arched upper sides; alternate bearing (on and off years) easily occurs, and resistance to pests and diseases weakens year by year. After entering the senescent stage (after the trees reach 30-40 years of age), yield decreases, the root system's absorption and transport capacity weakens, and bare areas in the inner canopy and at the base of scaffold branches worsen. The fruiting position is confined to the outer periphery of the canopy, essentially no new shoots develop, and the aging and dieback of fruiting branches become increasingly severe. Resistance during on and off years weakens and pests and diseases worsen. When branches or trunks are stimulated (heavy pruning and branch cutting, mechanical injury, etc.), latent buds readily sprout into water sprouts and root suckers, and the tree body often becomes incomplete and loses its cultivation value.

II. Field management in the late full-bearing stage and the senescent stage:

1. Apply more manure. Because the tree body depletes soil nutrients, soil fertility declines. Therefore, sufficient organic fertilizer must be applied to maintain tree vigor and yield. The fertilizer type should be mainly farmyard manure; the application rate is best at the standard of 1 jin of fertilizer per 1 jin of fruit. If there are many flower buds, appropriately more nitrogen fertilizer may be applied, supplemented with phosphorus and potassium fertilizer; otherwise, mainly phosphorus and potassium, supplemented with nitrogen fertilizer. As for the application method, in addition to the usual trench application, because the root system is sparser and weaker at this stage, attention should be paid to the depth of fertilization, and too many roots must not be broken. The dormant period is the key period for applying base fertilizer, and it is better to apply it after harvest and before leaf fall. Topdressing should be carried out before flowering, after flowering, and before fruit ripening respectively; use quick-acting organic fertilizer or chemical fertilizer, mainly phosphorus and potassium fertilizer. On the premise of not affecting the effectiveness of pesticide spraying, mix the elements needed by the fruit trees into the spray solution and apply foliar fertilizer, which takes effect more quickly.

2. Irrigate at the right time. It is best to irrigate once thoroughly before the soil freezes (winterizing water). This can meet the water needs during the flowering period. During the growing season, irrigation can be carried out according to soil moisture conditions. In the rainy season, accumulated water should be drained promptly to prevent root asphyxiation and death. After irrigation and rain, carry out intertillage and soil loosening promptly. Doing a good job of growing grass cover or cut grass cover in the pear orchard can increase soil organic matter and maintain soil moisture, and should be vigorously promoted.

3. Reasonable load. Timely flower and fruit thinning and reasonably retaining fruiting branches during winter pruning play a great role in maintaining tree vigor. The amount of fruit retained should be reasonably determined according to orchard management conditions (fertilizer and water, soil, etc.), and it is best to retain one fruit per 15-20 leaves. While removing the central fruit, do not retain fruit without leaves, cull fruit, or pest- and disease-damaged fruit; when the yield is sufficient, do not retain double fruit.

4. Control the outward shift of the fruiting position. Taking advantage of the characteristic that latent buds of pear trees readily produce new branches, measures such as heavy heading back, notching, and girdling can be adopted to solve problems such as bare rear parts and the outward shift of the fruiting position. For senescent tree orchards whose yield per unit area can no longer meet production requirements, new trees should be planted in advance in the rows and between plants 3-4 years earlier, or 2-3 year old large seedlings should be raised outside the orchard and transplanted, to prepare for renewing the whole orchard. However, senescent trees should not be dealt with hastily; the senescent trees should be gradually removed only after the young trees have achieved a certain economic benefit. When young and old plants are in the same orchard, pest and disease control should be done well.

III. Pruning of pear trees in the late full-bearing stage and the senescent stage

The main tasks of pruning in this period are to maintain tree vigor and yield and to solve the problems of the outward shift of the fruiting position and the weakening and dieback of fruiting branch groups. The pruning amount must not be too heavy, so as to keep enough leaves and enhance tree vigor. For incomplete plants, make full use of water sprouts emerging from latent buds to increase branch number and make the canopy as complete as possible. Adopt the method of renewal by heading back to renew drooping branches and fruiting branch groups, proceeding from top to bottom and from outside to inside, lightly cutting back year by year; do not rush. If there are sprouted suckers at the arched bends of drooping branches, they can be cultivated and headed back at their front ends; branches sprouting at wound sites and from the roots can also be appropriately utilized. Fruiting branch groups are very prone to aging and dieback after bearing fruit for many consecutive years, so detailed renewal pruning should be carried out during pruning; weakened branches at the tips can be headed back to more vigorous parts at the rear, generally with a heading-back ratio of about 2:1.

IV. Integrated control of pests and diseases

The focus of control should be placed on protecting the tree body, especially the control of branch and trunk pests and diseases, such as pear tree Valsa canker, pear tree dieback, and ring rot. For the control of other pests and diseases, integrated control can be adopted according to the specific conditions of the orchard, with the aim of protecting leaves, maintaining tree vigor, and achieving stable yield and high quality.