Cytospora Canker: Unraveling the Disease that Strikes Trees

Cytospora Canker is a fungal disease that primarily affects trees, causing unsightly and sometimes fatal damage. It is caused by various species within the Cytospora genus. Though common, it is often misunderstood and can be challenging to manage. This blog post delves into what Cytospora Canker is, its symptoms, how to prevent it, and what to do if your trees are affected.

Understanding Cytospora Canker

What is it?

Cytospora Canker is a disease caused by fungi in the Cytospora genus. It primarily affects woody plants and is often found in fruit trees like peach, cherry, and apple, as well as shade trees like willow, poplar, and spruce.

How does it spread?

The fungus is generally present in the environment but becomes problematic when trees are stressed or weakened. It enters the tree through wounds or natural openings and then grows within the bark.

Symptoms and Identification

Identifying Cytospora Canker requires careful observation of various symptoms:

  1. Cankers: Sunken, dark, oval-shaped areas on the branches or trunk.
  2. Oozing Sap: Infected areas may ooze a sticky, amber-colored sap or resin.
  3. Discolored Wood: The wood beneath the canker often appears discolored, usually dark brown to black.
  4. Foliage Symptoms: Branch dieback, yellowing, or wilting of leaves.

Prevention and Management

Since Cytospora Canker is challenging to treat once established, prevention and early management are essential.


  • Plant Resistant Varieties: If available, choose tree varieties that are known to resist the disease.
  • Water and Fertilize Properly: Healthy trees are less susceptible, so follow proper watering and fertilizing guidelines.
  • Avoid Injury: Minimize wounds from pruning or other activities, as they can be entry points for the fungus.

Early Detection and Management

  • Inspect Regularly: Look for early signs of the disease, especially if your trees are in an area known to have Cytospora Canker.
  • Prune Affected Branches: If you detect cankers, prune the affected branches well below the infected area.
  • Disinfect Tools: Always sanitize pruning tools between cuts with alcohol or bleach solution to prevent spreading the fungus.
  • Avoid Overhead Watering: Wet foliage can promote fungal growth, so water at the base of the tree instead.


Once established, Cytospora Canker can be very challenging to eradicate:

  • Continue Pruning: Keep removing affected branches, and consider consulting an arborist if the disease has spread widely.
  • Consider Fungicides: Though generally not highly effective for Cytospora Canker, specific fungicides might be used as a part of a management program.


Cytospora Canker is a complex disease that requires a nuanced understanding and careful management. By recognizing the symptoms, implementing preventive measures, and responding quickly if signs of the disease appear, you can help protect your trees from this damaging ailment.

Remember, the best defense against Cytospora Canker is a healthy tree. Proper planting, nourishing, and care practices can make your trees more resilient to this and many other diseases.

Caring for trees isn’t just about aesthetics or fruit production; it’s a commitment to preserving a vital part of our ecosystem. By understanding diseases like Cytospora Canker, we not only nurture our individual trees but also contribute to a healthier, more vibrant environment. Whether a home gardener or a commercial orchardist, we all play a role in this essential stewardship of nature.