How to grow grapefruit for high yield (how to grow big and delicious grapefruit)

As a tropical and subtropical fruit tree, pomelo is an evergreen tree of the Rutaceae family. It likes heat and light, is drought-resistant, and can be stored and transported. Its fruit is sweet and sour, and has high nutritional and medicinal value. Below we will introduce the methods and techniques of growing pomelo, so that the pomelo grown can be large and delicious.

1. Garden establishment and planting

1.1 Site selection

Pomelo is suitable for planting in fields with fertile and loose soil, convenient transportation, drainage and irrigation, and sufficient sunlight.

Grapefruit is not suitable for planting in fields with rich coarse sand and gravel, shaded light, and high groundwater levels. The soil in the field should be sandy loam with a soil pH range of 6.0 to 6.5.

1.2 Planting density

High ridge cultivation is usually adopted. In flat dry land or paddy fields in dam areas, the row spacing of grapefruit plants is 4m×5m, 33 plants/667m2.

If grapefruit is planted on a terrace or slope, the planting density can be appropriately increased, and the plant row spacing can be 3m (3.5m) × 4m.

1.3 Pond digging and pond filling

Specifications for digging ponds in paddy fields : pond surface width and bottom width ≥70cm and ≥60cm respectively, and depth ≥60cm; specifications for digging ponds in dry land: pond surface width and bottom width ≥80cm and ≥70cm respectively, and depth 60-70cm.

When returning the pond, topsoil and perishable materials are returned to the bottom of the pond; potassium sulfate fertilizer, calcium magnesium phosphate fertilizer, compound fertilizer and micro-fertilizer mixed evenly with the soil are returned to the middle of the pond; organic fertilizer mixed evenly with the soil is returned to the pond surface, eventually forming a tree planting pit.

1.4 Application of base fertilizer

When returning to the pond, apply base fertilizer, 10-20kg of organic fertilizer or farmyard manure, 0.5-1.0kg of compound fertilizer or calcium magnesium phosphate fertilizer per pond, mix evenly with the surface fertilizer soil and apply it in layers into the pond. When returning to the pond, it should be noted that the pond surface should be 20-30cm higher than the ground surface, so that it can be naturally leveled before planting .

1.5 Colonization

Planting time : Grapefruit can be planted from February to September . The best planting period is from June to July, which is in the rainy season and has sufficient sunlight, which is conducive to the growth of new roots and shoots, and the survival rate of planting is higher.

Planting method : Select strong, disease-free and insect-free 1-2 year old grafted pomelo seedlings for planting. When planting, cut off some old leaves or tender shoots to store water on the leaves.

It is recommended to cut off the overly long roots, make the roots evenly distributed in the soil, and plant in the center of the tree tray. The soil should be ≥5cm away from the grafting point and should not be higher than the grafting point. After compacting the soil, water it enough to establish the roots. The binding tape at the grafting point should be removed after the new shoots of the grapefruit seedlings emerge.

2. Fertilizer and water management

2.1 Fertilization of young pomelo trees

For one-year-old pomelo trees, nitrogen fertilizer is mainly applied, supplemented with appropriate amounts of phosphorus and potassium fertilizers. The purpose of topdressing is to promote early growth and accelerate the formation of a high-yield crown.

Since young trees have few roots and do not have a strong ability to absorb fertilizer, excessive fertilizer should not be applied. Apply 50 to 75 g of urea per plant each time, and apply top dressing 8 to 10 times a year. Then, gradually increase the amount of fertilizer as the tree ages.

For 2-3 year old pomelo trees, fertilization should be done 4 times a year.

(1) Apply spring shoot fertilizer (February-March), apply 0.5 kg urea/plant + 1.5 kg compound fertilizer/plant;

(2) Apply summer fertilizer to promote growth (late April to early May), applying 0.5 kg of urea per plant + 1.5 kg of compound fertilizer per plant + 10 kg of organic fertilizer per plant;

(3) Apply autumn shoot-promoting fertilizer (July-August), apply compound fertilizer 1kg/plant;

(4) Apply winter fertilizer (November-December), apply 20kg/plant of organic fertilizer + 1kg/plant of calcium fertilizer + 1kg/plant of compound fertilizer + 1kg/plant of potassium sulfate fertilizer + 25g/plant of trace element fertilizers such as boron, zinc, and magnesium.

2.2 Fertilization of fruit-bearing pomelo trees

In February and March, apply flower and fruit preserving fertilizers according to the condition of the trees. To avoid falling flowers and fruits and ensure neat spring shoots, apply 1kg of compound fertilizer per plant to old and weak pomelo trees that were insufficiently fertilized in winter.

If the initial fruiting pomelo trees are vigorous, topdressing is not necessary or the application of quick-acting nitrogen fertilizer should be controlled .

After the second physiological fruit drop of pomelo (late April to early May), fruit swelling fertilizer should be applied, including 5kg/plant of organic fertilizer + 0.5kg/plant of urea + 1kg/plant of potassium fertilizer + 1kg/plant of general calcium + 1.5kg/plant of compound fertilizer, in order to accelerate the swelling of pomelo fruit.

After the pomelo fruits are harvested (mid-to-late October), apply post-fruit fertilizer once to old and weak pomelo trees according to the condition of the trees, with 1kg of compound fertilizer per tree, to restore the tree vigor.

Usually, a circular fertilizer ditch (about 30cm wide and 35cm deep respectively) is dug from late November to mid-December, and winter fertilizer is applied in late December to meet the nutritional consumption of pomelo trees over the winter and the nutritional needs of spring shoot growth in the following year.

In the fertilizer ditch, apply 0.5kg urea, 1kg potassium fertilizer, 2.5kg compound fertilizer, and 50kg decomposed farmyard manure per plant. Mix well and cover with soil to 5 to 10cm above the ground.

2.3 Scientific water management

During the flower bud differentiation, budding and flowering periods of grapefruit trees, large-scale irrigation of grapefruit trees is strictly prohibited to avoid the emergence of new shoots and the occurrence of a large number of flowers and fruits falling.

If the soil lacks moisture, it should be watered appropriately, especially after the pomelo fruit is firmly seated, watering should be carried out in time to keep the soil moist.

No watering is required during the rainy season, especially during periods of concentrated rainfall, but waterlogging and drainage work must be done to prevent root rot and fruit falling.

The soil should be kept moderately dry during the harvest period, which is conducive to the conversion of sugar in the pomelo fruit and effectively improves the quality of the pomelo fruit.

3. Plastic and pruning

For branches about 30 cm in height that sprout in spring and summer, the tops should be pinched in time, and the excess buds should be removed.

In autumn, relevant measures (hanging, pulling, and supporting) are taken for vigorous pomelo trees to increase the opening angle, which has a moderate effect on the growth of the trees and helps them to bear fruit early.

We can use a knife to make three staggered ring cuts on the side branches in late September to inhibit the downward transport of nutrients from the leaves, help the leaves accumulate nutrients, and increase the amount of flowers the following year.

Then, after the autumn shoots and leaves mature, spray 1 to 2 times of 300 times of paclobutrazol to effectively prevent the grapefruit trees from sprouting winter shoots.

Controlling late autumn and winter shoots can accumulate nutrients and help differentiate flower buds on the fruiting mother branches the following year.

Generally, after the pomelo trees are harvested, dead branches, competing branches, overlapping branches, diseased and insect-infested branches are cut off, while the lateral branches, drooping branches and short fruit branches inside the crown are retained to maintain good light transmittance and ventilation of the crown, and promote high-quality and high-yield pomelo .

4. Thinning flowers and fruits

Given that pomelo trees have a large number of flowers, manual flower thinning is not only time-consuming but also labor-intensive, and is therefore usually not performed in production.

Flower and fruit drop is a phenomenon that occurs after the pomelo tree blooms. Artificial fruit thinning is generally carried out after the second physiological fruit drop. The densely packed fruits and deformed fruits are removed. Fruit thinning should be determined based on the number of flowers, the planned number of fruits to be retained, and the tolerance of the pomelo tree .

5. Bag pomelo fruit

Grapefruits are usually bagged in mid-to-late June . Before bagging, spray 1-2 times with pesticides to prevent and control diseases and insect pests (sunburn, scale insects and fruit flies).

The bagging time for pomelo fruit is 50 to 60 days, and the bags should be removed 10 to 15 days before selling the pomelo to allow the pomelo fruit to fully obtain sunlight and improve the quality of the pomelo fruit.

6. Prevention and control of major diseases and pests

The main diseases that harm grapefruit include gummosis, canker and scab, and the main insect pests include leaf miners, rust mites and red and yellow spiders.

6.1 Disease control

Gummosis mainly causes damage to branches and trunks. You can use a knife to scrape off the necrotic part first, deep into the wood , and then apply 100 times diluted 50% carbendazim solution or 100 times diluted 50% thiophanate-methyl wettable powder.

Canker mainly harms branches, fruits and leaves. To prevent and control this disease, quarantine should be strengthened, and it is strictly forbidden to introduce seeds or seedlings from the diseased area. The garden should be cleaned in winter, and dead branches, fallen leaves and fallen fruits should be burned in a centralized manner to cut off the source of the disease. Spray 80 times of 20% chloroquine or 500 times of 50% fungus and virus cleaning solution for prevention and control.

Scab disease mainly causes harm to tender shoots and young fruits of branches and leaves. It can be controlled by spraying 800 times diluted 75% thiophanate-methyl wettable powder or 1000 times diluted 50% carbendazim wettable powder.

6.2 Pest Control

Spray 500 times diluted 25% carbendazim aqueous solution or 1500 times diluted 5% imidacloprid emulsifiable concentrate to control leaf miners.

To control red and yellow spiders, you can use 3000 times diluted 50% clofenac to kill overwintering eggs, and 3500 times diluted miticide to control central insect strains.

Rust mites can be controlled by spraying 1000 times diluted 40% carbofuran.

7. Harvest at the right time

When the pomelo fruit is light yellow, choose a sunny day to harvest it in time. During the harvesting, storage and transportation process, care should be taken to handle it with care to avoid damage to the pomelo fruit.