It’s a delicate matter, trimming trees. It’s not an activity that should be performed haphazardly, without regard to strategy, tactic, or time of year. Trimming a tree, even one branch, creates a wound that the tree must heal, and in the interim leaves internal tissue exposed to pests and disease.
When a tree is cut or damaged, the tissue releases phytochemicals (metabolic chemicals) that play roles in plant growth or protection from predators or infection. Sugary sap and tender, soft wood are exactly what pests, sooty mold, and fungus feed on. These wounds create vulnerabilities to diseases that compromise the phloem, xylem, and structural integrity of the tree.
So does an injury not become fatal for a tree? Just like you and I have scabs that cover our cuts and abrasions, so do trees cover their wounds. The tree deploys parenchyma cells to form callus tissue over the affected area to seal the exposed wood tissue. The faster the tree can close the wound, the better, and that rate depends on the species and condition of the tree. Typically, a young, vigorous tree in good environmental conditions can close the wound quickly increasing its chance of survival.
Access to nutrients, sunlight, oxygen and quality soil will make a big difference in the health of the tree. For example, a tree growing in an open field would have major survival advantages over a tree planted in the sidewalk of a cityscape.
There are products on the market meant to improve wound closure by creating an immediate seal following a cutting. Some of these products are paints, and some are petroleum products. These can be helpful in areas where disease is a huge concern, such as the presence of oak wilt fungus. But generally, these products are not recommended because they limit oxygen and inhibit good callus formation, slowing the healing process.
Tips to optimize tree healing in pruning or trimming
While every cut presents some risk, you can observe good practices that strengthen the tree’s chances of healing and survival.
- Cut at the right time of year. During the cool weather months in late fall and very early spring, pests are dormant and diseases are a reduced threat.
- Disinfect tools when trimming diseased plants. You don’t want to spread disease to the next tree.
- Use sharp, well-conditioned shears or saws when cutting. Ideally, you want to make a clean cut and avoid tearing extra bark or leaving jagged edges or pieces.
- For small branches, make clean, 45-degree slanting cuts, right up to the next healthy bud or branch. This expedites healing and reduces any unnecessary dead wood left.
- For large branches, cut them flush to the collar at the base of the branch, careful not to damage the trunk. This will help the seal form between the trunk and the dead wood and protect the trunk.
- Never “top” trees. It creates concerns both for aesthetic reasons and the health of the tree.
- Avoid using any type of wound dressing unless there is a known, significant risk for oak wilt disease.
- If the tree is smaller, water and add fertilizer to help promote healing.
- Don’t over-trim. Trees can only tolerate having 10-15% of their foliage removed at one time.
- Only if absolutely necessary should you cut a limb that is 4’’ in diameter or bigger, due to the area of exposure it leaves.
Need help with tree trimming or pruning? Our capable team is complete with experts who can take care of any issues you face with your trees, from trimming and pruning, to cutting to stump grinding, and supportive reinforcements.
From our office location in Glen Arm, Manor Tree Service works in Baldwin, Hydes, Phoenix, Jacksonville, Fallston, and the Dulaney Valley area. Call our office or contact us here!