Arbor-wellness: Root rot and Cankers

How do I know if my tree has root rot problems or cankers?

Many symptoms of root rot mirror the signs of a pest infestation, which makes properly diagnosing it more difficult. The symptoms of root rot are sometimes easier to spot above ground. These can include:

• Gradual or quick decline without an obvious reason.
• Stunting or poor growth.
• Small, pale leaves.
• Wilted, yellowed, or browned leaves.
• Branch dieback.
• Thinning of the canopy.
• On some species, the fungus grows up from the roots in the inner bark and causes cankers, or sunken dead areas.

The most accurate way to diagnose a root disease is to dig below ground to see if decay is taking place. If needed, samples can be taken to a lab and tested to determine exactly what type of rot is occurring.

What is the best way to take care of root rots and cankers?

Tree root diseases are best controlled by prevention. If you have existing trees, make sure they are being watering correctly, that soil or mulch are not allowed to build up around the base of the tree and that the soil is allowed to dry out between watering. Ideally soil should be well structured and should drain properly. Where conditions warrant, making systemic soil treatments can be very helpful. Fall timing of these treatments allows the tree to take the material in and distribute it throughout the plant for best protection.

Pruning out and infected root can help if discovered early and access is not a problem. Always be sure to disinfect any tools you work with before using them again. When roots are pruned, one newer biological treatment is to inoculate the roots with a special pathogenic fungi the feeding on the rot fungi. This is a natural defense system that has proven successful in orchards and tree plantations where some rots can become a severe problem over time. Once the root is inoculated and the “good guys” are established, ongoing treatments for root rot can be eliminated.

What about cankers or bleeding on the trunk?

There are many fungi that cause this and even some bacteria may be involved. Being able to accurately diagnose what type of problem the tree has is critical to developing an appropriated treatment plan. If you are concerned about trees on your site having root rots or cankers, contact your Arborwell arborist for a professional assessment and recommendation.

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