Preventing Forest Tree Illness

pine trees

Root diseases usually thin or fade crowns over a period of years. Photo: Chris Schnepf.

Do not wait to act on insect and disease issues until after you see dead branches. Look for visible symptoms or signs of tree illness and learn how to prevent a favorable environment for organisms that harm trees. It is important to understand that successful methods for minimizing forest insect and disease problems are usually preventative, occurring before problems are noticed. Monitoring your forest for conditions that favor the insects and diseases common to your area can help prevent longer term problems and save you costs for culling or treating trees.

Success comes with focusing on two critical forest characteristics:

  • species composition and

  • stand density (as measured by the number of trees per acre, the basal area of the forest, or the stand density index, for instance).

Considering these two characteristics, ask questions that can help you prevent problems before they start. For example, is your forest heavily composed of species that are highly vulnerable to particular insects or diseases common to the area? Does your forest have too many stems per acre, extending an unintended invitation to bark beetles? Acting on the answers to such questions may keep you from losing trees or having to take challenging measures to save trees.

In your efforts to monitor conditions in your forest, it is valuable to gain some understanding of the forest ecology and succession patterns that have occurred historically where your forest is located. Information is available at Keeping Your Woodlands Healthy at and Forest Condition Reports from the USFS Forest Health Protection. After exploring such information, use it to think like a forester. Foresters commonly try to mimic the forest conditions that have been most resilient in the face of various insects, diseases, fire events, and climate extremes occurring in an area over the long term (say, 50 to 150 years). Some of these factors may change, depending on what happens locally with climate over the coming decades, but that possibility makes monitoring of forest lands even more important.

The following articles provide more information about monitoring your forest to keep it healthy:

Check with your local Extension office and State Forestry Department or Division for materials to help you decide what programs and information are available. Conservation Education and Trees work for us or Urban and Community Forestry resources are available from the US Forest Service and their Forest Service research locations. There are also Woodlands and Forestlands publications and assistance available from the USDA NRCS Service Centers in each state and their technical centers.


Chris Schnepf, University of Idaho and Sarah Workman, University of Georgia and USFS Eastern Forest Threat Assessment Center