How to Prune Orange Trees for Optimal Growth and Fruit Production
Pruning is essential for maintaining healthy, productive orange trees and is vital to orchard management (facilitates other agricultural practices). Proper pruning promotes good vegetative growth, and fruit quality and increases tree longevity. This article provides a comprehensive overview of orange tree pruning practices and principles, including training techniques, best practices for productive trees, and specific tips for pruning different orange tree varieties. Whether managing a professional high-density orchard or a small home garden, these techniques will help you maintain your orange trees' vigor, health, and productivity.
Training Orange Trees
The young, newly planted orange trees should be trained to give them the desirable frame/shape to support the crop and yield needs of the years to come and balance the canopy growth with the root system. The juvenile stage of orange trees lasts between 2 and 5 years. The young trees receive their first pruning when exported from the seedbed to be transplanted in the field. This pruning aims to remove part of the seedlings' root system and part of the crown.
- Heavy pruning in young trees that have yet to come to fruition generally delays their entry into fruition and should be avoided.
- Branching should be avoided for trees that have not yet reached a height of 50-60 cm (19.6-23.6 in) and 20 cm (7.8 in) of trunk above the bud union.
- When the above prerequisites are met, then the heading should be applied.
- Citrus trees are generally pruned to a central or modified leader shape (less often into hedges or espaliers).
- Farmers are advised to create up to 8 limbs, leaving enough space between them. Thinning must be applied to leave 3 to 6 strong limbs in the coming years.
- To avoid injuries, the branches left to grow must have enough space, good access to sunlight, good air circulation (not crowded), and not cross, rub, or touch.
- Finally, removing all the fruits from the trees during the first year of production is essential to prevent the exhaustion of tree resources.
Pruning Mature Orange Trees for Fruit Production
Selective Pruning for Health and Productivity
In general, removing part of the crown from healthy adult citrus trees will directly result in a proportionate reduction of their production but is necessary to maintain a long term. Consequently, light pruning (trimming) should only be limited to making small interventions to the shape of trees. No more than 15-20% of the foliage should be removed during a pruning session. If pruning is focused on reducing the size of the tree, a canopy removal of up to 20-30% is acceptable. While the frequency of the pruning may vary per case, it is common to apply light prunings every 2-5 years. Our goal is to facilitate aeration and sunlight penetration to the inner part of the tree as well as to facilitate various cultivation operations.
One of the main reasons to prune a productive orange tree is to maintain its vigor and health. As a result, farmers should remove damaged, infected, infested, and dead branches. In general, it is best to start pruning from the top down. Forked branches should be thinned out, and the most vigorous ones should be kept. Even in case the pruning does not take place every year, the farmer must constantly remove all sucker shoots that compete with the tree canopy for recourses. However, if there is a gap in the canopy or we want to replace one limb branch, we can maintain 1-2 suckers growing with a correct orientation and good vigor. This practice should be applied to both bearing and non-bearing trees. Unwanted branches of any kind (e.g., with wrong orientations) should be removed as early as possible to avoid losing the plant's resources. Ideally, branches should have an angle greater than 30 degrees from the vertical axis. In the case of co-dominant leader-branches, the farmer should keep only one of them.
Skirting - Skirt Pruning
In orange trees, it is common to apply skirting (manually or mechanically). During this pruning, the farmer removes or shortens the length of branches that are touching or are very close to the ground. A distance of 45 to 75 cm (18 to 30 inches) from the ground should be maintained to keep the canopy clean, reduce the risk of disease infections (like Phytophthora foot rot), keep pests (snails, ants, and rodents included) away and facilitate harvesting. At the same time, this will protect the branches and the oranges from herbicide and fertilizer applications and soil management practices. Skirting is more challenging in varieties that have multiple productions per year, such as Valencias and Summer Navels. In these cases, pruning should be applied after the fruit set or soon after harvest.
Growers are advised to apply only thinning cuts (drop-crotching) to control the shape and height of the trees. Topping or heading are practices mostly applied to trees trained as hedges. As a rule of thumb, the topping height should be two times the row's middle width.
Fruit thinning
Fruit thinning in orange trees is a critical management practice aimed at optimizing fruit size and quality before harvest. Hand thinning, the most precise method, involves manually removing smaller, scarred, or deformed fruits to reduce crop load and improve the size of the remaining fruit. It is typically carried out after natural fruit drop, at the beginning of the cell expansion stage of fruit growth, when fruits are about 30–40 mm in diameter. Thinning early has the most significant impact on fruit size, although it is labor-intensive and economically viable only for higher-value varieties like mandarins or navels intended for export. Proper crop load assessment considers tree health, age, and the capacity of individual branches to support fruit. This method requires careful judgment to ensure sufficient thinning while maintaining an even crop distribution across the tree.
When it is best to prune orange trees
In general, better results can be achieved if the pruning is done in early spring or, in some cases, in early fall when there is no risk of frost. Vegetation renewal is achieved more through spring pruning and less through the autumn pruning. The autumn pruning generally encourages the development of a late wave of growth, which is very sensitive to winter frosts. In the warmest regions with plenty of sunlight and high temperatures during summer, it is vital to leave sufficient foliage to protect the scaffold branches and the trunk and prevent sunscald or sunburn. As an extra protection, some farmers paint the tree trunk and, in some cases, part of the scaffold branches with watered-down white acrylic paint.
Pruning Damaged Trees - Restoration pruning
Trees that suffer damage from frost, very high temperatures, or rodents need special pruning. We do not need to prune if the damage is light and has only infected foliage and young shoots. However, careful pruning is necessary when a severe frost has affected larger branches.
Please note that the pruning shear must be sterilized through an alcohol solution, as it can transmit various fungal or bacterial diseases to the orange trees.
References
https://crfg.org/wp-content/uploads/CITRUS-PRUNING-Presentation.pdf
https://edis.ifas.ufl.edu/publication/HS1267
https://www.agric.wa.gov.au/citrus/citrus-pruning?page=0%2C1
https://extension.arizona.edu/node/5311
https://www.dpi.nsw.gov.au/__data/assets/pdf_file/0003/242814/Hand-thinning-citrus.pdf
4.) How to grow Orange Trees from seed
5.) How to grow an Orange Tree from cuttings
6.) Growing Orange Trees for Profit
7.) Orange Tree Climate & Soil Requirements
8.) Choosing Orange Tree variety
9.) Orange Tree Propagation & Pollination
11.) Orange Tree Fertilizer Requirements
12.) Orange Tree Water Requirements
13.) Pruning Orange Trees
14.) Orange Tree Harvest & Yields
