Sooty bark disease is a tree disease caused by the fungus Cryptostroma Corticale. It primarily affects deciduous trees, particularly sycamores and maples, although other species can also become susceptible under certain conditions. This disease is often associated with prolonged periods of warm, dry weather, which can weaken the tree’s natural defences and create a favourable environment for fungal growth. Trees under stress, such as those experiencing drought or other environmental pressures, are at a heightened risk of infection.
The recent hot summer has caused an outbreak of the fungal disease.
The fungus infects the tree by entering through natural openings or wounds in the bark. Once inside, it establishes itself in the vascular system, disrupting the tree’s ability to transport water and nutrients effectively. Over time, the infected bark begins to split and reveals an underlying layer of black or dark brown spores, which gives the disease its characteristic “sooty” appearance. This spore layer is a distinguishing feature and a sign that the disease has progressed to an advanced stage.
Sooty bark disease poses significant risks to affected trees. As the infection spreads, it can lead to branch dieback, reduce the tree’s vigour, and, in severe cases, cause its eventual death. The release of fungal spores into the environment can also pose health risks to humans. Inhalation of the spores, particularly by individuals with pre-existing respiratory conditions or allergies, may cause respiratory irritation or more serious conditions like hypersensitivity pneumonitis.
Prevention and management of sooty bark disease involve a combination of proactive measures and responsive actions. Since stressed trees are more vulnerable, maintaining tree health is a critical preventive strategy. This includes regular watering during dry periods, mulching to retain soil moisture, and avoiding unnecessary injury to the tree’s bark. Early detection is also essential. Signs such as bark splitting, reduced foliage density, or the presence of dark spores should prompt further investigation.
Once a tree is infected, managing the disease becomes more challenging. Infected trees cannot be cured, but appropriate actions can minimize the spread of the fungus to nearby healthy trees. Pruning and removing affected branches can help limit the disease’s impact, although care must be taken to avoid spreading spores during this process. Tools used for pruning should be disinfected, and removed material should be carefully disposed of to prevent contamination. In severe cases, complete tree removal may be necessary, particularly when the infection poses a risk to other trees or human health.
New guidance has been released by the AA Sooty Bark Disease (SBD) please follow the link. This new guidance was released last week
Medical impacts of working on trees with SBD
These spores can cause maple bark disease (MBD) in humans, a hypersensitivity pneumonitis (HP) with similar symptoms like COPD, allergic asthma, influenza or flu-like infections and interstitial pneumonia.
PPE should be used when managing trees. Generally, that is a face mask with a filter.
SBD is prevalent in East Anglia on Sycamore following the heatwave summer we had. Many of my reports have indicated this disease on trees we have seen as guidance, and we have directly attempted to alert the contractors to its presence when monitoring.
In my opinion, a health and safety procedure should be in place within the RAMS (Risk Assessment and Method Statements).
Awareness of sooty bark disease is crucial for property owners, arborists, and landscapers. With changing climate patterns, the conditions that favour the disease may become more common, increasing its prevalence. Understanding the symptoms, risk factors, and management techniques can help mitigate its impact on individual trees and larger ecosystems.
Taking a proactive approach to tree care, staying vigilant for early signs of infection, and consulting professionals, when necessary, can all play a role in minimizing the effects of sooty bark disease. Preserving tree health not only protects valuable green spaces but also contributes to broader environmental stability.
If you think your trees show signs of SBD please don’t hesitate to contact us.
