Many tree services focus on the canopy of a tree but overlook the fact that its root system needs care as well. As a matter of fact, issues with roots, soil, and water contribute to nearly 80% of all landscape tree problems. The roots are vital to the health and longevity of a tree. Once the root system is compromised, the majority of the tree will undergo decline that ranges from moderate to severe, with tree death being a possible outcome. When a tree exhibits one or more problems such as dying branches, pest infestations, disease, fungal attacks, or general decline, these can often be traced to underlying health issues within the tree’s root system.

Most tree roots are found in the upper 24” of soil and the majority of thin, water absorbing roots are located in the top 6” of soil. Roots play an integral part in delivering adequate water and nutrients throughout the tree. They also store food and provide necessary support. Roots need to be routinely inspected for structural defects, compaction, mechanical injury, and more. Here are some of the most common problems that we encounter:

• Buried Root Collars: Buried root collars are widely considered to be the leading cause for urban tree decline and death. When a tree’s root collar (the area where the trunk meets the roots) is buried below the surrounding soil or mulch, this keeps the collar moist, which inhibits the movement of oxygen and carbon dioxide through the phloem and leads to a variety of critical issues such as preventing the movement of food within the tree. Buried root collars also make the tree susceptible to soil-borne pathogens, encourage the growth of girdling roots, and more. All of these issues stress the tree and make it more vulnerable to disease, infestations, and decline. Buried root collars are the result of improper planting, mulch volcanoes, soil grading, and a number of other factors. Mulch volcanoes are particularly common and are very easy to treat.
• Soil Compaction: This is another leading cause of death among urban trees. A tree’s roots need oxygen in order to grow. When compaction occurs above the key structural roots, this ability is severely compromised since compaction diminishes the available soil pores (air spaces) that hold oxygen. As a result, compaction limits the oxygen diffusion rate in the soil and results in root suffocation. Soil compaction can come from heavy foot traffic, construction machinery, paving over root systems, and many other actions.
• Girdling Roots: These are roots that wrap around the base of the tree trunk, thus limiting water and nutrient uptake. This leads to decline and dieback of the canopy. Girdling often happens in situations where the root collar is buried below surrounding soil or mulch, particularly with mulch volcanoes. Girdling roots must be identified and removed sooner rather than later. Otherwise, as the girdling roots mature, the damage may be irreparable.
• Root Disease: There are a several types of fungi that can cause root diseases, the most common of which are Armillaria, Phytophthora, Pythium, and Fusarium. The fungi break down the tree’s feeder roots, thereby reducing the root’s ability to perform necessary functions. Trees with buried root collars or mechanical injuries are at risk for fungal attack.
• Mechanical Injury: Grading, trenching, digging, and other similar activities can sever and wound a tree’s root system if the tree is not properly protected.
• Over Competition: Too much competition for vital nutrients from surrounding bushes, grass, flowers, and shrubs can stress a tree. It is usually best to mulch the area around a tree rather than to allow plants and grass to grow.
• Over or Under Watering: Too little water is obviously bad for a tree. But too much water is also bad, since it floods soil pores and restricts oxygen uptake. In short, too much water will drown the tree.
• Over or Under Fertilization: Too much fertilization can injure a root system, and too little fertilization results in a lack of essential nutrients.
• Poor Soil: Soil with unbalanced pH, a lack of organic matter, too much soluble salts or chlorides, a lack of micronutrients, and so forth can negatively impact a root system.