Scientists estimate that there are about 3 trillion trees on Earth, and chances are, there’s one or two in your yard. Trees do a lot for us, like clean the air, prevent flooding, cool our homes, and even increase our property values. But like people and other animals, trees can become ill. There are a variety of ailments that cause trees to become sick, and knowing what to look for improves the odds of saving your trees! These are some of the signs of a sick tree.
Fungus on the trunk
It’s not terribly uncommon for fungus of some kind to grow on the trunk of a tree, and while it looks cool, you should consider what fungi like growing in the most: rotting plant matter. If you see mushrooms or toadstools growing out of the trunk of your tree, it may indicate that there’s an internal rot happening under the bark of the tree.
Once an internal rot has begun, it’s difficult to cure. Most arborists would tell you to simply remove the tree to keep the fungus from infecting other trees. The key to dealing with tree rot is preventing it from happening. Fertilizing your trees with a 0-20-0 or 0-46-0 fertilizer will help keep your growing tree strong. Pruning dead branches and “suckers,” which are branches growing near the base of the tree, will help prevent rot as well.
If you noticed your once tall and sturdy tree has begun to lean, it may be a sign that your tree is experiencing some kind of root damage. Another sign of root damage is the tree sending up new branches from the base of its trunk. This is usually a sign that the tree is under a great deal of stress. Poor soil compaction and exposed roots can cause severe damage to a tree. Making sure tree roots are properly covered will go a long way to protecting the health of your tree.
If your tree suddenly has a sour-smelling liquid seeping out of it and leaving dark streaks down the bark of the tree, it may have something called alcoholic slime flux. It can impact willow, ash, maple, birch, beech, oak, sycamore, cherry, and ash trees. It’s caused by bacteria feeding on a tree wound.
The good news is if you see the liquid seeping out of the tree, that’s actually a good sign. The infection needs a dark, damp environment to thrive, so ejecting it from the tree is a sign that the tree is fighting back and healing.
Trees will usually overcome the problem on their own. There’s not much you can do about it. Prevention is important though. Trim away dead and broken branches and do your best to avoid planting trees near foot and vehicular traffic.
Yellow and brown leaves
If it’s the middle of summer and you see your tree’s leaves browning and yellowing, that could be a sign that your tree is suffering from armillaria root rot. This is when a fungus in the soil attacks the roots of your tree. This root rot can also manifest in the form of excessive wilting or major tree branches dying off.
It’s a well studied disease, but there isn’t a silver bullet for curing it. Adding nutrients to the soil can help strengthen the tree and taking steps to reduce stress on the tree can help as well. Ultimately the tree will either heal itself or die within a few seasons.
White powder on leaves
Unlike many of the diseases on this list, this one is actually quite treatable. If you find white powder growing on your leaves, it is likely that your tree is experiencing powdery mildew. It usually starts as small, white spots but will eventually spread, especially if you live in a humid environment.
If you see powdery mildew, consult a local arborist as soon as you can. The disease will need to be handled by a professional. If you treat it yourself, you can inadvertently kill the tree. Left untreated, powdery mildew can kill your tree as well.