Mastering the Art of Plum Tree Pruning: A Comprehensive Guide

Pruning plum trees is an essential practice for maintaining their health, productivity, and overall beauty. A well-pruned plum tree not only yields more fruit but also prevents disease and structural weaknesses. However, the process can seem daunting for beginners. This comprehensive guide will walk you through every step of plum tree pruning, ensuring you have the knowledge and confidence to keep your trees thriving for years to come.

Why Prune Plum Trees?

Before diving into the how-to, let’s understand why pruning is so crucial:

• Increased Fruit Production: Pruning encourages new growth, which is where most fruit develops. Removing old or unproductive branches redirects the tree’s energy to fruit-bearing wood.
• Improved Air Circulation: An open canopy allows for better airflow, reducing the risk of fungal diseases like brown rot, which are common in plum trees.
• Enhanced Sunlight Penetration: Sunlight is vital for photosynthesis and fruit ripening. Pruning opens the tree, allowing light to reach all parts of the tree.
• Structural Integrity: Removing crossing, rubbing, and weak branches prevents breakage and ensures the tree develops a strong framework.
• Easier Harvesting: By maintaining a manageable size and shape, pruning makes harvesting your delicious plums easier and safer.
• Tree Health and Longevity: Regular pruning helps to eliminate diseased and dead wood, promoting overall tree health and extending its lifespan.

When to Prune Plum Trees

The timing of pruning is critical and differs based on the plum tree’s age and type. Here’s a breakdown:

• Young Plum Trees (1-3 years old): Prune in late winter or early spring while the tree is dormant before new growth begins. This is the crucial time to establish the tree’s structure.
• Mature Plum Trees (4+ years old): For most plum varieties, prune after fruiting in the late summer. This helps to reduce the risk of silver leaf disease, a common issue with plums. Late summer pruning also allows sufficient time for the tree to heal before winter. Avoid heavy pruning in winter because that promotes the growth of watersprouts.
• Japanese Plum Varieties: Typically bear fruit on previous year’s wood. Prune these in late spring/early summer shortly after harvesting the fruits.
• European Plum Varieties: Usually bear fruit on spurs (short side shoots) that persist for several years. Prune these primarily in late summer after harvest.

Note: Avoid pruning during wet weather as this can increase the chances of infection.

Tools You’ll Need

Having the right tools makes the pruning process safer and more effective. Here’s a list of essentials:

• Hand Pruners (Secateurs): Ideal for small branches (up to 1/2 inch in diameter). Look for bypass pruners as they provide a clean cut.
• Loppers: Used for thicker branches (up to 1 1/2 to 2 inches in diameter). Choose ones with comfortable handles and sharp blades.
• Pruning Saw: Essential for branches larger than 2 inches in diameter. A curved pruning saw is often the most effective.
• Gloves: Protect your hands from thorns and rough bark.
• Safety Glasses: Protect your eyes from flying debris.
• Ladder: If needed to reach higher branches. Choose a sturdy ladder and be cautious when using.
• Disinfectant: For cleaning your tools between cuts (a 10% bleach solution or rubbing alcohol) to prevent spreading disease.
• Tree Wound Dressing (Optional): For larger cuts to help seal the wound and prevent infection.

Step-by-Step Guide to Pruning Plum Trees

Now, let’s get into the specifics of pruning your plum tree:

1. Start by Identifying Problem Areas

Before you even make a cut, carefully assess your plum tree. Look for:

• Dead, Diseased, or Damaged Branches: These should always be the first to go. Dead wood is brittle and provides a potential home for pests and diseases. Diseased branches, like those with signs of canker or fungal infections, need to be removed to prevent spread. Damaged branches, such as broken or bent ones, create entry points for infections.
• Crossing or Rubbing Branches: These branches can wound each other and hinder air circulation. Choose one of the branches to remove completely, removing the least vigorous one.
• Suckers: These are new shoots that grow from the base of the tree or roots. They steal energy from the main tree.
• Water Sprouts: These are fast-growing, vertical shoots that emerge from older branches. They tend to be unproductive and crowd the center of the tree.
• Branches Growing Inward: These branches crowd the center and block air circulation and sunlight. They should be removed to open up the canopy.
• Weak or Thin Branches: These branches often don’t produce well and can be easily broken. Removing them directs the tree’s energy to more productive branches.
• Overly Dense Areas: Areas with too many branches need to be thinned out. This allows for sunlight and air to reach all parts of the tree.

2. Prune from the Top Down

When pruning, start with the highest branches first. This will make it easier to see what needs to be removed as you work your way down the tree. It also reduces the chance of damaging lower branches by falling cut ones. As you prune, frequently step back from the tree and assess the overall shape and structure. Ensure the tree looks balanced with good airflow and sunlight penetration.

3. Remove Dead, Diseased, and Damaged Wood

Using the appropriate tools, remove all dead, diseased, and damaged branches. Make clean cuts at the branch collar (the swollen area where the branch meets the trunk or a larger branch). This area has specialized cells that help with healing. Avoid leaving stubs, as these can hinder the wound-healing process and are more prone to disease. Use clean, sharp tools and sterilize them between cuts, especially when dealing with diseased branches, so you don’t accidentally spread the disease to other parts of the tree.

4. Address Crossing and Rubbing Branches

Identify branches that cross each other or rub together. Remove the least desirable branch entirely at its point of origin, using your pruning saw or loppers. When removing branches, cut them flush with the branch collar. Avoid cutting into the branch collar, as it is critical for proper healing. Removing the rubbing branches will reduce the chances of injury and allow for better air circulation. As you do it, pay attention to the overall shape of the tree. Always try to remove the branch that interferes the most with the tree’s overall shape and desired growth direction.

5. Thin Out the Canopy

Next, remove inward-growing branches and watersprouts. Aim for an open vase shape (or a modified central leader system in younger trees) where the branches do not overlap and sunlight can penetrate easily. Remove the weakest, thinner, less productive or poorly positioned branches, starting from the interior of the canopy and working outwards. This allows light to reach the center of the tree for optimal fruit production. When thinning the canopy, remove a few branches at a time and check the effect on the overall appearance of the tree before you proceed. Try to balance the shape and ensure light and air can reach all parts of the tree. Avoid removing too much at once as that will stress the tree. Thinning the canopy is very important since an overcrowded tree tends to be prone to diseases and pests.

6. Shorten Longer Branches

If any branches are too long or overly vigorous, you can shorten them by cutting back to an outward-facing bud or lateral branch. This encourages the tree to grow outwards, further opening the canopy. When shortening the branches, cut at a slight angle, about a quarter of an inch above a bud. This encourages growth in the direction of that bud. Always remember to cut at a bud that faces away from the center of the tree. This will help direct new growth away from the center, increasing air circulation and light penetration. The goal is to encourage lateral growth rather than vertical. This step is important for both the tree’s structure and to make it easier to harvest the fruit. Avoid excessively shortening the branches, as this may cause the tree to produce watersprouts.

7. Remove Suckers and Water Sprouts

Remove any suckers growing from the base of the tree and water sprouts growing vertically from the branches. These are typically unproductive and sap energy from the tree. Cut suckers at their point of origin at the base of the trunk or roots, making sure you remove all the growth. Cut watersprouts flush to the branches they are emerging from, using your pruning shears or loppers. Regular removal of suckers and water sprouts is essential for the healthy development and productivity of your plum tree.

8. Shaping Young Trees

When pruning young plum trees, focus on establishing a strong central leader, or a main trunk. Select the strongest, tallest shoot to become the central leader. This central leader should grow vertically. Remove any competing shoots that are too close to the central leader or are trying to take over. Select 3-5 main scaffold branches (the primary branches that will form the tree’s framework) that are evenly spaced around the central leader. These scaffold branches should ideally be positioned at a wide angle from the trunk. Remove any other branches that might compete with the development of these main scaffold branches. Prune the scaffold branches lightly to encourage secondary branching, cutting back to outward-facing buds. The goal in the first few years is to establish the basic structure of the tree. Young trees require lighter pruning to avoid hindering their growth.

9. Shaping Mature Trees

Mature plum trees require more maintenance pruning. Prune each year to maintain the shape and size of the tree and to remove dead and diseased branches. Mature trees should have an open canopy, free from excessive branches and any overlapping or rubbing. Mature trees, because of their size, may also require larger tools like pruning saws. Pay attention to the branches that bear fruit. Mature plum trees can be very heavy with fruit so making sure all branches are strong will prevent branch breakage. Maintain a good tree structure and airflow so that the weight of the fruit does not cause the tree to weaken. Regularly prune mature trees to maintain their health and productivity.

10. Inspect the Tree

Once you’ve finished pruning, step back and assess your work. Make sure you have achieved the goal of removing the undesirable branches, maintaining the desired shape and the openness of the canopy and if there are any more problematic branches that you may have overlooked. Make any necessary adjustments by doing additional pruning if necessary. Ensure that the tree looks balanced and that there is good light penetration and air circulation. Clear the area of any removed branches to avoid pests and diseases.

11. Aftercare

After pruning, consider applying a tree wound dressing to larger cuts (over 2 inches in diameter) to help seal the wound and prevent infection and protect against pests. Monitor the tree’s growth throughout the season. Water the tree as needed, especially after periods of drought. Remove any dead branches that appear over the season. Add some compost around the tree in spring for extra nutrients, if needed.

Tips for Successful Pruning

• Use Sharp Tools: Sharp tools make clean cuts, which heal faster. Dull tools can tear and crush branches, creating openings for disease.
• Don’t Prune Too Much at Once: Heavy pruning can shock the tree and encourage excessive water sprout growth. Try to prune a maximum of 25-30% of a tree’s branches per year.
• Take Your Time: Pruning is not a race. Take your time to assess the tree and make thoughtful cuts.
• Observe Your Tree: Learn the growth habits of your particular plum variety. Some varieties are more prone to certain problems, so specific pruning techniques can be used accordingly.
• Consult an Expert: If you’re unsure about pruning your plum tree, consult with a certified arborist or horticulturist. They can offer personalized advice based on the specific needs of your tree.
• Clean Your Tools: Always disinfect your tools between cuts when dealing with diseased branches, and always at the end of your pruning job.
• Be Patient: It may take some time for the tree to react to pruning. Do not expect immediate results. Pruning is a long-term investment in the health and productivity of your plum tree.

Conclusion

Pruning plum trees may seem complex at first, but with a little knowledge and practice, you can master this important skill. Remember to focus on removing dead, diseased, and crossing branches, opening the canopy, and shaping the tree for optimal health and fruit production. By following this guide, you’ll be well on your way to enjoying abundant harvests of delicious plums for many years to come. Happy pruning!