Sooty Bark Disease: An In-Depth Look

Sooty Bark Disease (SBD) is a serious fungal disease that mainly affects mature sycamore trees. It’s a condition that can lead to the decline and death of affected trees, and understanding its causes, symptoms, management, and prevention is crucial for arborists, foresters, and homeowners alike. This comprehensive blog post will delve into Sooty Bark Disease, offering insights into the underlying causes, how to recognize it, and what can be done to manage and prevent it.

What is Sooty Bark Disease?

Sooty Bark Disease is caused by the fungus Cryptostroma corticale. It affects mainly sycamore trees, although it has been observed in other species too. The disease gets its name from the characteristic sooty black appearance that infected bark takes on as the disease progresses.

Symptoms and Identification

Recognizing Sooty Bark Disease in its early stages can be challenging, but as it progresses, the symptoms become more apparent:

  1. Bark Splitting: The bark may start to crack and split, exposing the underlying layers.
  2. Black Spores: The fungus produces masses of black spores beneath the bark, giving the inner bark a sooty appearance.
  3. Leaf Wilting: Affected branches may exhibit wilting and premature leaf fall.
  4. Dieback: Branch dieback is a common sign, and the tree may show general signs of stress and decline.

Causes and Conditions for Development

Sooty Bark Disease is more likely to occur under certain conditions:

  • Drought Stress: The disease often appears after periods of drought when the trees are stressed.
  • Wounds: The fungus can enter through wounds or cracks in the bark.
  • Warm Weather: The disease is more common in areas with warm summers, as the fungus prefers higher temperatures.

Management and Control

Managing Sooty Bark Disease requires a combination of proactive and reactive measures:

1. Monitoring

  • Regularly inspect sycamore trees, especially after periods of drought or warm weather.

2. Pruning

  • Remove infected branches and dispose of them properly to prevent the spread of spores.
  • Ensure proper pruning techniques to avoid creating unnecessary wounds.

3. Watering

  • Provide adequate watering during dry periods to reduce stress on the tree.

4. Fungicides

  • Though not typically used for Sooty Bark Disease, in severe cases, fungicides may be considered. Consult with a professional arborist.

5. Remove Infected Trees

  • In severe cases, the removal of the infected tree may be necessary to prevent the disease from spreading.


Preventing Sooty Bark Disease starts with maintaining healthy trees:

  • Proper Planting and Care: Ensure trees are planted correctly and receive appropriate care, including watering, mulching, and fertilizing as needed.
  • Avoid Unnecessary Injury: Be careful not to wound the tree during lawn care or other activities.
  • Choose Resistant Varieties: If possible, plant sycamore varieties known to be resistant to SBD.

Conclusion: A Manageable Threat

Sooty Bark Disease is a significant concern for those with mature sycamore trees, particularly in regions prone to drought or warm weather. Early detection, proper management, and careful prevention strategies can mitigate its impact.

A deeper understanding of the disease, combined with vigilance and care, can ensure that our beautiful sycamores continue to thrive and enhance our landscapes despite the threat of Sooty Bark Disease. If you suspect an infection in your sycamore trees, consult with a professional arborist or tree care specialist, as timely intervention can make a significant difference in the outcome.