Disease Management Through Proper Pruning

There are many reasons to prune a tree or shrub. According to industry standards, there should always be a written objective for the plant that is being pruned. Common examples of these objectives are: improved branch spacing and structure, additional clearance from a house, additional ground clearance for mowing or walking, or to maintain a dominant central leader.

One very useful, but less common objective is pruning for disease management.

For a disease to develop, there are four items needed:

• the pathogen
• a suitable environment
• a host
• and time.

An objective of disease management pruning aims to influence environment and time.

Most plant diseases thrive in dark, moist environments. You can see leaf spot or needlecast diseases begin their infections in the lower, interior areas of a tree and spread outward/upward from there. That is because these lower, interior areas usually experience more shade and less air circulation than the upper branching.

Pruning a crabapple to help limit foliar disease

Through proper pruning, we can create more airflow and sunlight penetration throughout a tree’s crown. This allows for foliage to dry off faster after a rain event, limiting the amount of time that the foliage is a suitable environment for infection to take place. On a larger scale, strategic removal of crowded trees can reduce disease issues as well.

Pruning for disease management is performed without a significant change in the overall appearance of your tree. In fact, it is often a complement to other common pruning objectives such as maintaining healthy branch spacing and structure.

Certain diseases may still require fungicide applications for desired control. However, pruning is a beneficial management tool and often overlooked when it comes to suppressing diseases. This can be useful to limit certain leaf spot issues such as Apple Scab, Tar Spot, and Anthracnose. Evergreen diseases such as needlecast or Cytospora canker can be reduced with strategic removal of individual trees within a grouping that might become crowded over time as they each grow larger

If you are curious about how disease management pruning could help complement your tree care program, please give us a call. Our Wachtel Tree Science Team of Certified Arborists are happy to provide and execute a complete disease management plan for your property!

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Disease Management Through Proper Pruning

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