Walnut kernels are delicious and healthy, used for preparing desserts and snacks. To obtain a rich harvest, gardeners must know how to care for the tree and which agronomic procedures it requires. One of the essential practices is the removal of excess shoots. This article details the types of autumn pruning for walnut trees and their benefits.
Table of contents
Why Prune a Walnut Tree in Autumn
In late summer or early autumn, shoot growth slows down, and the plant prepares for the cold. Autumn pruning revitalizes the tree.
The procedure removes all unnecessary parts of the plant - dry and weak shoots, infected, thin, and diseased branches. The walnut tree's immunity increases, making it less susceptible to diseases and insect pest attacks. Pruning prepares the tree for winter, allowing it to withstand frosts resiliently and bear fruit abundantly the following year.
Pruning improves the plant's appearance - gardeners remove all chaotic and intertwined shoots. After the procedure, the tree looks well-groomed and neat.
Is It Mandatory
Autumn pruning is mandatory if gardeners want to revitalize the tree, extend its lifespan, and receive a rich and tasty harvest annually. Mature trees need the procedure to increase the number of fruit-bearing branches.
If the plant is not pruned, the shoots become dense, productivity decreases, and diseases and pests appear more frequently. Weak branches break during windy conditions. Rehabilitating such a tree is difficult and can take several years.
Timing for Autumn Pruning
The timing of the procedure depends on when the walnut tree sheds its leaves. This typically occurs in September or October. When choosing a date, pay attention to the climatic conditions of the growing region and the temperature.
Gardeners recommend pruning the plant on a cloudy and windless morning at a temperature not lower than +10°C. The procedure should not be performed in rainy weather.
Note! Prune the walnut tree 2 - 3 weeks after fruiting. If flowering occurred in May, the harvest is gathered in early September. If in June, the nuts are harvested until early October. Waiting for full ripening is not necessary - the fruits can be collected green and placed in a box for 2 weeks.
Types of Pruning
There are several types of walnut tree pruning - rejuvenating, sanitary, formative, and regulatory.
Each serves its own purpose and is carried out according to strict rules. Incorrect technique can do more harm than good to the plant.
Rejuvenating Pruning
Rejuvenating pruning is relevant for trees older than 10 years, when the yield of mature plants gradually declines, and the number of nuts becomes fewer each year.
During pruning, gardeners remove lateral branches, long new growths, and shoots growing inward. The procedure increases the plant's lifespan, creating space for the development of new, fruit-bearing branches. The tree's canopy acquires the correct shape, and the nuts become larger.
The procedure is also relevant for trees that consistently bear poor fruit. Such plants are pruned every 7 years. The older the tree, the more intensive the pruning. Rejuvenating pruning can also save a tree that has been damaged by frost.
Sanitary Pruning
Sanitary pruning is conducted if the tree has many dry and weak shoots. These become deformed, covered in spots and plaque, and change color. Such branches create a favorable environment for disease development and pest reproduction, making sanitary pruning a preventive measure.
The procedure also restores the plant's strength if it has been ill. Walnut trees are most commonly affected by anthracnose, bacteriosis, and brown spot.
Formative Pruning
Formative pruning aims to stimulate the growth and development of healthy shoots and increase yield. The procedure strengthens the walnut tree's immunity, and the canopy becomes powerful and resistant to external factors.
Formative pruning is also used to help young plants shape their canopy. It is important for the tree to grow evenly in length and width, with new shoots distributed evenly along the skeletal branches. The procedure is carried out in October when sap flow has ended.
Note! During formative pruning, gardeners shorten the central trunk and all skeletal branches. This is done to obtain a new skeletal branch if an existing one has been damaged.
Regulatory Pruning
Regulatory pruning is carried out starting from the 7th - 8th year after planting. By this time, the canopy has formed a large number of small shoots and lateral growths that hinder normal fruiting. Leaves do not receive the necessary amount of sunlight, shading each other and nearby shoots.
Gardeners recommend cutting back the semi-skeletal branches of the lower tier and thinning the canopy. Shoots with mechanical damage and wounds are also removed.
Formative Pruning Schemes
Canopy formation is done using the leader, tiered, or cup-shaped scheme.
The leader technique involves distributing frame branches around the tree trunk in a spiral. Lateral branches are left on the 3 lower tiers until fruiting begins, after which they are thinned out until completely removed. The leader scheme ensures the canopy is well-lit from all sides, promoting increased yield.
In tiered pruning, 3 frame branches are left on each tier, with a distance of at least 15 cm between them. A mature tree should have about 5 - 6 tiers. The lower tier is removed during the procedure - no branches should grow within 1.5 m of the ground. The canopy is thinned during tiered formative pruning.
The cup-shaped scheme is used to make harvesting more convenient. A bowl-shaped canopy allows air to pass through, creating favorable conditions for fruit development. Pruning is carried out over 3 years, annually removing central branches until the tree has 4 skeletal branches spaced 30 cm apart. The remaining shoots are crossed with branches from the upper tiers.
Preparing the Walnut Tree for Pruning
Work begins only with trees taller than 1.5 m. After fruiting, the walnut tree is watered for the last time, and the soil is loosened to allow better water absorption. Fertilizer is not applied in autumn; it is better to do this in spring and summer.
Gardeners ensure the tree is free from insect pests and diseases. If there are signs of damage, the plant is treated first, and only then is the procedure started. Gardeners also maintain the cleanliness of the garden plot - it should be free of debris, weeds, and plant residues. Fallen leaves are collected and burned.
How to Correctly Prune a Walnut Tree in Autumn
To prune a walnut tree in autumn competently and without harm to the plant, gardeners prepare tools in advance and study the instructions.
Required Materials and Tools
For removing green growth and thin young shoots, use garden shears or sharply sharpened secateurs. A dull tool harms plants - it leaves ragged cuts that heal slowly and become a focus for disease and pest development. The handle of the garden tool should fit snugly in the hand and not slip. Handles with rubberized grips are convenient. Before use, disinfect the tool in a weak potassium permanganate solution.
For pruning thick and old branches, use a hand or petrol saw. For high branches - a ladder and a lopper with long aluminium handles. Experienced gardeners recommend paying attention to personal safety rules.
Note! For any type of pruning, garden pitch is essential. This is a thick, soft substance based on wood resin. Garden pitch protects cuts from bacteria and microbes, promoting rapid wound healing. When using pitch, wear rubber gloves and a respirator.
Step-by-Step Pruning Instructions
Begin the procedure by inspecting the tree - gardeners determine which branches and on which tier need to be removed.
Then proceed with pruning:
- shorten two-year-old shoots longer than 60 cm and dry branches;
- saw off broken and damaged branches from the harvesting process;
- remove 1 - 2 skeletal branches growing in the centre of the canopy;
- cut out thin and long shoots with offshoots;
- trim young growth;
- remove water sprouts and shoots affected by insects;
- coat the cut areas with garden pitch.
Mistakes to Avoid
A common mistake made by novice gardeners is cutting branches flush. It is recommended to leave short fruit-bearing branches about 20 - 40 cm so they can turn into fruit-bearing shoots the following year. Gardeners also forget to disinfect garden tools - which can lead to the walnut tree becoming infected with diseases or damaged by insect pests.
Walnut trees also suffer when gardeners do not maintain tiering. Each tier should have 3 - 4 skeletal branches left. Otherwise, formative or regulatory pruning will be ineffective.
Pruning Features for Young and Old Trees
When pruning young trees (up to 5 years old), pay attention to the young green growth. There is a lot of it on the lower tier, causing poor light penetration for the branches. Remove the growth with garden shears - it is thin and does not require special tools. Some believe that after pruning this growth, the walnut tree does not need to be coated with garden pitch - small wounds will heal on their own.
Note! In the first years, pay special attention to formative pruning. Even though the walnut tree is not yet fruiting, it is crucial during this time to ensure the branches grow in the right direction. Overcrowding in young plants is not allowed.
Starting from the 7th - 10th year, perform rejuvenating pruning annually. This is as important as timely watering or fertilizing. If the tree's canopy is not visible, remove all non-fruiting and deformed shoots. Do not be afraid of such radical measures - this will rejuvenate the tree and extend its life. Gardeners ensure that branches do not grow inward into the canopy.
Aftercare
Once the wounds have healed, spray the walnut tree with a solution of Bordeaux mixture or urea. This is done to protect the tree from diseases and pests. Treat the plant in the morning or evening, using a sprayer with the solution.
Mature plants winter without shelter, while young trees are wrapped in burlap for the winter. The base of the trunk is mulched with hay or wood chips - this protects the root system from freezing. This rule is especially relevant for regions with cold and variable climates.
Tips from Experienced Gardeners
Experienced gardeners recommend conducting formative pruning in several stages. In the second year after planting, select a strong vertical shoot and pinch the remaining branches. In the third year, trim the lateral growths and shape the canopy, and in the fourth year - leave 5 - 6 skeletal branches in the canopy.
Gardeners advise monitoring the tree's condition during the procedure. For example, if the walnut is sick, it is better to postpone pruning. There is no point in trying to revitalize the plant until it is free from bacteria and microbes.
If the wounds do not heal for a long time after pruning, reapply garden pitch. If unavailable, use a clay mash: mix 2 parts clay with 1 part cow manure and 2 parts fine hay. Dilute the mixture with water to a thick consistency.
Conclusion
Both young and perennial walnut trees require pruning. During the procedure, gardeners remove old, dry, non-fruiting, and damaged shoots. Use garden shears for thin branches and a saw for thick ones.
The tool must be sharp; otherwise, ragged wounds heal slowly. Afterwards, coat the shoots with garden pitch, treat with a copper sulphate solution, and prepare for wintering. Without pruning, the tree grows weak, dense, and bears poor fruit.