Key Points and Detailed Methods of Navel Orange Pruning Techniques

Trimming and adjusting a thing is not because the thing is bad, but because one wants it to develop better. The same is true for pruning flowers, grass, and trees. Although the flowers are already blooming beautifully and luxuriantly, wanting them to be better and to give people more enjoyment of beauty requires pruning them.

Navel Orange Pruning Techniques

1. Pruning methods for young navel orange trees

The main goal is to cultivate the canopy, so light pruning is appropriate, avoiding excessive thinning and heavy heading back.

On the basis of trunk heading of the nursery stock, cultivate the main branches in the 1st and 2nd years, and select and retain secondary main branches and lateral branches; in the 3rd year, cultivate the extension branches of the main branches and secondary main branches, and rationally arrange the lateral branch groups. Properly thin out overly dense shoots; inner-canopy shoots and relatively weak shoots in the middle and lower parts of the canopy should generally all be retained. All late autumn shoots that sprout after September 10 should be completely pruned off.

2. Pruning methods for navel orange trees in the initial fruiting stage

Continue cultivating and expanding the canopy, select and head back the extension branches of the scaffold branches at all levels, and allow a moderate amount of fruiting. Retract or head back the fruiting branch groups after fruiting. For overly long vegetative branches, leave 15-25 cm and pinch off the tips.

Before each flush of shoots, wipe out the early sporadic sprouted buds to achieve uniform shoot flushing.

The final autumn shoot flush should be completed uniformly in mid-to-late August, and all late autumn shoots sprouting after September 10 should be completely pruned off. Light pruning should be the main approach, avoiding excessive thinning and heavy heading back. Properly thin out overly dense shoots, and prune off from the base the water sprouts and upright branches that disrupt the tree shape. Pay attention to using water sprouts by bending branches and heading back to fill gaps in the canopy.

3. Pruning methods for navel orange trees in the full fruiting stage

Maintain a relative balance between growth and fruiting. Tree height is generally controlled below 3 m, the thickness of the green leaf layer is about 1 m, and the canopy coverage rate is 75%-85%. Timely retract fruiting branch groups, branch groups that dropped flowers and fruit, and declining branch groups.

Prune off dead branches and diseased and pest-infested branches, and thin out clustered branches. For trees with too many scaffold branches and severe canopy closure, use the large-branch pruning method to prune off from the base the overly dense or improperly positioned large branches, maintaining ventilation and light penetration.

For trees with many flowers, mainly thin out flowering branches and slender weak branches; cut back to the base the previous year's autumn shoot fruiting mother branches to promote new shoots, combining thinning with heading back. For vigorous trees with few flowers, prune lightly, removing only some upright vegetative branches to favor fruiting.

Navel Orange Fruit Retention Methods

1. From after flower drop to the second physiological fruit drop period, spray the leaves 2 to 3 times with 0.15% Huangjia natural brassin 5000 times plus new-type nutrient liquid fertilizers such as Jinkuizi L, P, K extract 500 times, Yelüling 500 times, etc.;

2. Wipe out summer shoots once every 7 to 10 days;

3. Continue pruning, mainly thinning, to improve canopy ventilation and light conditions, prune off dead branches and diseased and pest-infested branches, and reduce sources of disease and pest infection;

4. From mid-to-late May to early June, apply Yuhuang ester to prevent navel yellow fruit drop.

Navel Orange Fertilization Methods

1. Ring trench fertilization: According to the size of the canopy, with the trunk as the center, open a ring trench near the outer edge of the canopy. The depth of the trench depends on the depth of root distribution, generally 20-30 cm deep and 30 cm wide. The advantages of ring fertilization are that it saves fertilizer and is simple and easy to carry out, but the area is small and roots are easily injured, so it is often used for fertilizing young trees.

2. Radial trench fertilization: According to the size of the canopy, dig 4-6 radial trenches in the tree plate, about 30 cm wide, shallower near the trunk and gradually deeper outward. This method injures fewer roots. Change the fertilization position every other year or every other time to expand the fertilization area.

3. Strip trench fertilization: Open strip trenches between rows or between plants of navel orange trees, 30 cm deep and 30 cm wide, and cover with soil after fertilization. Alternate opening trenches between plants and between rows in different years. It is suitable for fertilizing adult navel orange orchards, especially closed-canopy navel orange orchards.

4. Hole fertilization: Evenly dig 4-8 holes at the outer edge of the canopy, 20-30 cm deep and 30 cm wide. Apply fertilizer into the holes, and cover with soil after it seeps down. The hole fertilization method is simple and injures fewer roots, but the fertilization area is small, so it is suitable for applying liquid fertilizers.

5. Whole-orchard fertilization: Evenly broadcast fertilizer over the whole orchard, then turn it into the soil. It is suitable for adult navel orange orchards where roots fill the whole orchard, but the fertilization depth is shallow and easily causes roots to grow upward, so it should be used alternately with other methods.

Main Diseases of Navel Orange

1. Fruit cracking disease

First, choose varieties (lines) with relatively strong cracking resistance. Generally, varieties (lines) with oval fruit shape and small or closed navel have better cracking resistance, such as Newhall, etc.; second, strengthen scientific management to enhance tree vigor. Especially during the drought period from after the plum rain to before the autumn rain arrives, special attention should be paid to water management, with timely irrigation or watering (spraying) to keep the soil moist frequently and promote normal growth and development of the fruit. Third, during the rapid fruit expansion period, spray foliar potassium fertilizer 2-3 times in succession. For foliar potassium fertilizer, 0.2% monopotassium phosphate or 0.3% potassium sulfate compound fertilizer can be used, and in early to mid-July, use a mixed solution of 200 mg/L "920" plus 800 times methyl thiophanate and an appropriate amount of Xianghu to heal the cracks and prevent cracking from occurring again.

2. Sunscald disease

Strengthening scientific management and covering the orchard with straw and other materials to preserve moisture is the basis for preventing sunscald disease; planting forage grass or interplanting green manure in the orchard can reduce sunscald disease; in high-temperature seasons, do not spray pesticides such as machine oil emulsion and lime sulfur mixture, so as to avoid worsening the occurrence of sunscald disease. In the early stage of sunscald disease, paste white paper on the surface of sunscalded fruit, and pull branches and leaves to shade the fruit to reduce direct sunlight exposure. Irrigating or spraying water regularly in the high-temperature seasons of summer and autumn can prevent and reduce the occurrence of sunscald disease.

3. Navel yellow disease

First, start with cultivating robust tree vigor and appropriately increase nitrogen fertilizer to raise the tree's nutritional level; second, before flowering, pull strong vigorous autumn shoots into a drooping or horizontal state so that most flowers face downward when opening, reducing sun-facing fruit and preventing the occurrence of navel yellow; third, from early to mid-June to mid-to-late July, in combination with fruit retention, spray 30-40 mg/L "920" solution twice in succession, and from late July to late August, apply 600 times "Yuhuang ester" solution to the navel part of the fruit to inhibit the occurrence and spread of navel yellow disease.

Pruning navel orange trees is intended to remove some branches and fruits and seeds that are not robust enough and to concentrate nutrients to supply the more robust branches, so as to produce fuller and better fruit. In addition to pruning techniques, some of the disease and pest control, fruit retention, and fertilization techniques described in the article are also very effective.