Diagnosing an Unhealthy Pine Tree

Master gardener Paul James is taking a look at Allison's not-so-healthy pine tree. Allison informs Paul that there was construction done in the area of the tree’s roots about a year ago. It used to be a much prettier, happier tree before the construction.

Paul determines a number of problems with the pine that he will try to address in order to save the tree:

Problem 1: Too much pavement

Problem 1: Too much paved surface around the base of the tree has resulted in soil compaction and poor oxygen exchange, which is not good for the roots and can result in die-back in the upper branches.

Problem 2: A weeping wound, the result of too-close pruning

Problem 2: Flush pruning cuts have left open wounds that allow a lot of tree sap to flow.

Problem 3: Too much dead wood

Problem 3: Dead branches can attract insects and disease.

To help the tree, Paul and Allison are going to limb up the pine. This involves removing dead or dying lower limbs, and should invigorate the tree’s health.

When limbing up a tree, be sure to leave an inch or so of wood to retain the branch collar so the pruning wound heals properly. How high you limb up depends on the length of your pole pruner. Paul and Allison take the opportunity to also tidy up the red oak growing next to the pine, where the two trees have been crossing branches.

To address the soil compaction and stressed roots, Paul shows Allison how to use an auger, like you would use to plant bulbs, to drill holes in the soil. They drill dozens of holes, each about a foot apart. If they hit a tree root they just reverse the drill and try somewhere else.

After drilling the holes, Paul helps Allison fill them with a composted product that contains beneficial fungus known as mycorrhizae. It dramatically increases the roots' ability to take up nutrients and fight disease. In return, the roots feed the fungus. This symbiotic relationship results in improved plant growth, prolonged life, less need for fertilizers and, hopefully, a much healthier tree. It’s a natural way of promoting the health and vigor of the tree, but it takes a while so don’t expect overnight results.

One more thing is crucial to a healthy tree: deep, thorough watering. Try for 30 minutes, and watch for runoff so you don’t waste water. A good watering should get way down into the subsoil. It will help the tree, and also help get the beneficial fungi growing actively.