An overgrown and overly dense tree crown can pose a lot of problems to the health of your tree.

Issues and Dangers

Poor air circulation can destroy your tree's health. When air can't circulate easily due to crown density, it's also likely that little light is reaching the inner branches. Leaf molds, mildew, and bacterial problems often become severe because of the density of branches and foliage. Insect pests can also travel throughout the crown more easily in crowded conditions. Without ample light, the inner leaves and branches decline, which makes them even more prone to fungal and bacterial diseases, as well as insect blights.

Further, these now weakened branches will rub against one another, so small injuries are likely happening up in the canopy. Eventually, rubbing branches can begin to die off. They may break and fall to the ground, or they may just drop on their own due to a condition known as branch drop syndrome.

Signs of Crown Density Issues

Fortunately, the symptoms of crown density are easy to spot. Most obvious is that little light will reach the ground beneath the tree. Ideally, on a sunny day, there should be at least dappled sunlight under the tree.

Leaves may also be a paler green than usual, or you may notice gray, white, or green mold growth on leaf surfaces, or discolored spotting. Inner branches will have sparse foliage, with most of the leaves concentrated on the outside and top of the crown where light and air circulation are still available. There will likely be a lot of creaking on breezy days as branches rub together, and you may notice friction damage on branches or an increase in the number of branches falling to the ground.

Prevention Techniques

Prevention requires little more than proper pruning. Crown pruning should take place in late winter, before the new leaf buds begin to open and while the tree is still dormant. If it has been several years since the tree was last pruned, it may take two to three years before it can be brought back into excellent shape. This is because no more than 1/4 of the crown should be removed at any one time, or it can shock the tree.

Your trimming service will begin by cutting out the branches that are already dead or badly damaged. Then, they will tackle all those branches that are rubbing together. If this hasn't opened up the crown sufficiently, they will carefully trim out additional branches.

Contact a tree trimming service in your area if you suspect poor air circulation is affecting your tree's crown.