Like many other facets of the natural world, trees are the subject of innumerable myths and misunderstandings. As professional arborists, our job is to help separate fact from fiction, thereby allowing our clients and readers to better care for their trees. While some of the most common myths are only slightly off base and essentially harmless, others are wholly incorrect, and may lead to tree damage, should you follow the purported advice.
1. Wounded Trees Heal – When trees suffer damage, they undergo the process of compartmentalization to help wall off the injured tissues. The damage suffered always remains, although healthy wood often grows around it.
2. Trees Use Deep Roots to Stay Upright – While trees produce a few deep roots, most of the roots lie in the upper 12 inches or so of soil. Instead of relying on deep roots to anchor a tree, trees send their roots out radially to grip the ground and keep them standing.
3. Trees Must Be Pruned Following Transplantation – Historically, many believed that trees should be pruned when transplanted, to balance the crown with the roots, which often sustain damage during the process. However, time and research has shown this to be a misguided practice, and trees should not be pruned during transplantation so that it can produce as much food as possible, which helps the process of establishment.
4. Tree Wounds Must Be Painted – Although still practiced by some, most arborists have stopped painting tree wounds as a matter of course. Aside from special cases involving specific pathogens, the research demonstrates that trees heal more quickly when not painted.
5. Tree Hollows Should Be Filled with Concrete – Historically, people have often filled hollow trees with concrete for stability's sake. Aside from serving as a serious hazard to any tree workers who may cut down the tree in the future, cement does nothing to improve the integrity of a tree; in fact, the practice usually reduces the tree’s chances of survival.
6. “Topping??? Is a Safe and Effective Pruning Technique – The practice of topping is almost universally destructive to trees. Often carried out on trees that have outgrown their space; topping causes trees to produce numerous watersprouts, which are likely to fail in the future. Additionally, topping exposes a tree to a variety of pests, fungi and bacteria, which may compromise its health and vigor.
7. Trees Should Not Be Pruned During the Spring – Some trees – particularly maples (Acer spp.) among others – will “bleed??? copious amounts of sap if pruned during the spring. While unsightly, the trees suffer no harm from spring pruning.
8. Trees Always Benefit from Fertilization – Trees growing in areas in which the soil is deficient in nutrients may benefit from the application of a slow-release fertilizer. However, fertilizing trees that do not require supplemental nutrition may suffer damage to their roots. Fertilization should always be conducted in response to specific nutrient deficiencies.
9. Trees Must Be Pruned Following Root Damage – As with transplantation, trees that are undergoing stress usually respond best when equipped with a full canopy of leaves.
10. New Trees Must Always Be Staked – While some saplings benefit from being staked to the ground, those that grow without such reinforcement usually develop more stable root systems and trunks. However, some municipalities require the use of tree stakes – in such cases, it is important to remove the stakes as soon as the tree and law allows.
If you ever have questions about the proper way to care for your trees, contact Arborist Now – San Francisco's first choice for tree care. One of our ISA-certified arborists can help you with any tree-related need, from planting to pruning to removal.