I get lots of pictures of sick trees. Most of the time the first photo sent to me is a declining canopy. Maybe a picture of an ugly leaf. After all, that’s what we tend to notice first as our eyes occasionally gaze upward to the living behemoths that shade our parks, yards, and homes.
There is one thing I always request of a client before proceeding with any type of diagnosis of the ailing tree: A photo of the base of the trunk as it emerges from the ground. Why is this section of the tree so important? Because this is where I tend to find the majority of the problems in large shade trees.
Planting depth
If you walk in the forest or a park with older established trees, look at the base of the trunk. More than likely you will see the trunk flare out at the base. This is called the root flare. The important thing to note for trees is that roots are adapted to being buried in the soil, but the root flare and trunk must be above the soil line. If it looks like a telephone pole sticking out of the ground, the tree is planted too deep.
Please know, most trees are already planted too deep in their container at the time of purchase. Often you will need to gently excavate the top few inches of soil in the pot until you identify a distinct flare or the first structural root. Some species (notably evergreens) may not have a clear root flare as young trees. That’s when you identify that first structural root as your guide.
Planting a tree too deep does not equal immediate death. Few things kill a tree instantly besides a chainsaw. A tree planted too deep will have a shortened life span as the root flare and any portion of the buried trunk slowly succumb to rot. Instead of a 200-year-old oak, maybe it will last 10 to 20 years. Not bad for the average length of time Americans own a home, but not great considering the oak’s potential lifespan.
Mulch
Another situation I often encounter is a tree, young or old, that is planted at the perfect height. The root flare is visible. The tree is healthy. The only thing to do is mulch the tree. What unfortunately happens too often is homeowners (and some landscapers) pile mulch up against the trunk of the tree. We call this volcano mulching and is akin to planting the tree too deep.
Trees with mulch mounded against the trunk create conditions that are favorable to rot and decay around the trunk. The recommended technique is to mulch the root system, not the tree, at a 2- to 4-inch depth, going as wide as practical, and leaving a 2-inch gap between the mulch and the tree trunk.
Arborist woodchips are a recommended type of mulch as these tend to be coarse and don’t pack down like some shredded wood mulches. These are often readily available in Illinois. Shredded wood mulch are not a bad mulch option, and I use these when I can’t get my hands on arborist woodchips. Shredded fall leaves are also a favorite of mine as a means to reuse what is often seen as a waste product.
Good Growing Tip of the Week: Looking for arborist woodchips? Many tree care and utility companies are looking for places to dump their woodchips. It never hurts to give them a call and see if you can get a load. Many municipal yard waste sites also have free woodchips for their residents.
***Report Courtesy of the University of Illinois Extension Office***
