Pruning organic fruit trees

Pruning is required to regulate the growth and shape of fruit trees, vines, and bushes. Because many of these are expected to support heavy crops, they need to develop a strong and resilient framework. This can usually be achieved through a combination of variety selection, and effective management which utilises a range of organic cultivation techniques such as soil enhancement, biological controls, companion planting, regular pruning, and fruit thinning. Immature trees and bushes are pruned to stimulate the correct orientation and solid growth of supporting limbs and branches. Over several seasons, the foliage is pruned into a shape which will eventually provide good protection for developing fruit while maintaining a reasonable degree of physical accessibility. Along with regular fruit thinning, skilfully administered pruning stimulates new growth, and can improve the quality of seasonal fruits. Once fruit trees and bushes reach their mature size, pruning maintains a tidy appearance and facilitates garden hygiene through the periodic removal of overcrowded, dead, diseased, and damaged portions of the plant.

To achieve the best results, pruning should be undertaken at the appropriate time of year using high quality, well maintained tools. It is important to avoid nitrogen rich supplements during the preceding season, since these will encourage uneven growth flushes and compromised fruit development. For most fruit species, winter is the correct time to prune. Winter pruning stimulates replacement growth which enables the overall shape and size of the plant to be influenced. There is less likelihood of infection when plants are dormant and minimal quantities of sap progress to the extremities. When fruit trees are heavily pruned in spring or early summer, the effort that goes into new growth is wasted. A light pruning during this growth phase will stimulate fruiting. The removal of half to three quarters of each new shoot improves the circulation of air and light, encouraging the formation of fruit buds. This should not be confused with fruit thinning which is removal of a portion of the immature fruit to enhance the quality of the remaining crop. Many organic orchardists will prune their older fruit bearing trees, and then wait several weeks before tackling the young and immature plants. Pruning takes some time to master and this approach provides the opportunity to practice and reach competency on the most firmly established and resilient plants. It is an effective way of minimising crop losses, particularly for the delicate stone fruit such as nectarines, and peaches.

High quality garden tools are designed to last a lifetime. They are expensive but should never be substituted for the poorly manufactured items sold in surplus and discount department stores. Pruning shears, loppers, secateurs, saws, and knives are best purchased from specialist garden suppliers with knowledgeable staff. A well designed tool will contain sufficient ergonomic features to support correct cutting techniques while maintaining a high level of physical comfort. This is particularly important for gardeners with arthritis and other conditions contributing to a reduced manual dexterity. Stainless steel blades are an excellent choice however there are alternatives which have gained popularity in recent years. Heat treated tungsten and Teflon coatings, similar to those applied in cookware and engine components are certainly worth considering.

To be effective in their operation, pruning tools must be kept scrupulously clean, well oiled and sharp. Blunt and dirty blades will soon damage fruit plants and provide opportunities for infection and disease. To limit the possibility of cross infection between individual plants, it is strongly recommended that pruning blades be wiped down with a soap solution then dried before using them on another. At the end of the session, these tools should be carefully inspected then cleaned with a mineral spirit before oiling both the blades and associated moving parts.

While there is a wide range of pruning methods and techniques, the basic approach to cutting should remain the same. Whenever possible, secateur or knife cuts should be made above the bud with the cut angled away from it. This enables rainwater to drip down the stem, protecting the bud and top of the exposed cut from bacterial rot and fungus. The cuts need to be clean and decisive to prevent damage to plant tissue. Larger branches need to be removed with loppers or a pruning saw. When the selected branch is heavy, it is safer and more effective to remove this in separate stages.

Beginning from the lower surface of the branch, the first cut should be angled upwards and approximately forty five degrees outwards from the trunk. Aim this preliminary cut at least three hundred millimetres outward from the branch collar or final cut, as anticipated. This assists the branch to fall easily with minimal splitting once a second cut is driven directly down from above. The second cut should begin at the top of the branch just above the undercut. Follow through until the weight of the branch causes it to separate from the tree. Having removed the additional weight, a final cut can be made at the branch collar or further out if required, cutting straight from the top to the bottom of the branch. This practice increases the number of actions required but greatly reduces the risk of forked branches splitting down into the trunk and causing extensive damage to the bark and sensitive internal vessels of the tree.

Like most essential practices in organic horticulture, the technical and aesthetic elements of pruning are widely debated in both professional and amateur circles. Most comprehensive garden publications will contain the foundation elements of a recognised pruning approach. These elements can be directly applied to achieve a satisfactory result. They can also be adapted or expanded with some of the supplementary techniques and approaches gained through wider reading, observation, and practical experience. Once the basic principles of cutting are mastered, they can be employed with any of the popular guidelines which demonstrate pruning in a sequence of instructional steps.

The following sequence is provided as a guideline for pruning mature fruit trees. Beginning with an inspection around the base, remove any root suckers to prevent their enlargement and competition for the water and nutrients required for upper growth. Check the base of each trunk for any discoloration or mottling which may indicate treatable problems like root parasite or fungal growth. Moving upwards, check each trunk for stability then select any limbs which need removing. It is good practice to begin by clearing any dead, damaged, or diseased limbs. This is important for safety reasons and assists with the planning and execution of later cuts.

After tackling the dead wood, remove any low, drooping limbs. In most instances these will be heavily shaded by higher growth and unable to provide fruit. These limbs drain resources which are better utilised for central growth and seasonal fruit production. Similarly, rapid upright growth in trees and outward growth in the case of wall trained bushes should be restricted. Vertical flourishing of high foliage does not support valuable fruit production in trees and outward growth of wall trained bushes is likely to cast productive sectors in shadow, with the potential to impact adversely upon fruit ripening.

The next step involves removal of crossing and dense parallel growth. Excessive parallel growth restricts the availability of sunlight for developing fruit. Crossing growth generates friction which can damage bark and create access for parasites and disease. Once all damaged and unproductive growth has been removed, trees and bushes can be shaped to accommodate future growth and optimum fruit production. Many organic fruit growers shape citrus and stone fruit into the traditional conical pattern with upper limbs cut back further than lower limbs. This enables maximum quantities of sunlight to reach developing fruit. Once the larger branches are trimmed in this manner, smaller ones should be selectively thinned to remove redundant foliage and encourage new growth.