Trees, like all living organisms, can develop various external features and growths. These formations sometimes appear unusual, prompting questions from property owners. Observing them provides insights into a tree’s health and biological processes. Understanding these natural phenomena is a first step toward responsible tree care.
Understanding Common Tree Growths
One common type of tree growth is a burl, which appears as a swollen, woody outgrowth often found on the trunk or branches. Burls are characterized by deformed grain patterns within the wood.
Another type is a gall, which manifests as abnormal swellings or deformities on various tree parts, including leaves, twigs, or trunks. Galls vary considerably in size, shape, and color.
Cankers are distinct from burls and galls, presenting as localized, often sunken or discolored lesions on the bark. These patches can appear dead or dying.
Finally, fungal conks, also known as shelf fungi, are the fruiting bodies of wood-decaying fungi. They often appear as shelf-like structures protruding from the trunk or branches, indicating internal fungal activity.
What Causes Unusual Tree Formations
Burls often form as a tree’s response to stress, such as injury, fungal or viral infections, or genetic predisposition. This stress can trigger an abnormal proliferation of xylem production, leading to the development of dense, misshapen wood tissue. The tree creates this growth as a defense mechanism to wall off damage or irritation.
Galls are primarily caused by insects, such as wasps, mites, or aphids, laying eggs or feeding on the plant, or by certain fungi, bacteria, or viruses. These organisms release chemicals that manipulate the plant’s hormones, triggering abnormal cell growth and forming the protective structure of the gall around the developing larvae or pathogen.
Cankers typically result from fungal or bacterial pathogens entering the tree through wounds, such as pruning cuts, mechanical damage, or environmental stress points. Once inside, these pathogens kill bark and underlying tissue, creating the characteristic sunken lesions.
Fungal conks are visible signs of internal wood decay, meaning a fungus is actively breaking down the tree’s structural wood. The conk itself is the reproductive structure of the fungus, producing spores that can spread to other trees. The presence of a conk indicates that the main body of the fungus has already established itself within the tree’s wood, sometimes for several years before the conk appears.
Assessing the Health Impact of Tree Growths
Most burls are generally considered benign and rarely pose a significant threat to a tree’s overall health. While large burls might potentially weaken a branch or trunk, they often do not compromise the tree’s structural integrity or lead to its decline.
Similarly, galls are largely aesthetic concerns and typically do not harm the tree’s health, especially when found on leaves. However, large galls on stems or twigs can sometimes interfere with the movement of water and nutrients, potentially causing minor localized dieback or weakening the affected portion.
Cankers can be more serious, as they represent areas of dead tissue that can girdle branches or even the main trunk. If a canker encircles a stem, it can disrupt the tree’s vascular system, leading to dieback of the parts above the canker and potentially the death of the tree if the trunk is girdled. The severity depends on the canker’s size, location, and whether it is actively spreading.
Fungal conks, conversely, almost always indicate significant internal decay within the tree. The presence of conks suggests that the wood-decaying fungus has been active for some time, which can severely compromise the tree’s structural stability and make it a potential hazard, particularly in strong winds or ice storms.
Managing or Addressing Tree Growths
When unusual growths appear on a tree, it is generally advisable to observe them over time for any changes in size, color, or appearance. Maintaining the tree’s overall health through proper watering, mulching, and avoiding unnecessary injury can enhance its natural defenses.
Most burls and galls do not require specific treatment, as they often do not negatively impact tree health. For cankers, if they are on smaller branches and appear active, pruning the affected branch may be an option, provided it can be done safely and without creating new entry points for pathogens. However, if a canker is on the main trunk or a large limb, removal is often not practical or beneficial. For fungal conks, their presence strongly suggests internal decay, and intervention is often warranted.
If a growth is large, rapidly expanding, appears to compromise the tree’s structural integrity, or if fungal conks are present, consulting a certified arborist is recommended. An arborist can accurately diagnose the type of growth, assess the extent of any internal damage, and recommend appropriate management strategies, which might include removal of hazardous limbs or, in severe cases, the entire tree. Professional assessment ensures safety and promotes the long-term health of the tree.