The more common organisms are species of Phytophthora, Pythium and Fusarium . Fungi that attack large, woody roots suppress growth, decay food-transporting cells, reduce food storage and reduce structural support for the tree. Yellow, chlorotic foliage from root disease. Typical symptoms associated with root diseases often are confused with mineral deficiencies because high numbers of dead roots reduce water and mineral uptake. Symptoms of root problems from construction damage or other detrimental activities may appear one to several years after the damage occurred.
Direct examination can verify a disease.
Carefully excavate roots by removing a small patch of the bark. The most effective way to reduce the possibility of root injury and disease is to keep the tree healthy and vigorous. A healthy root environment consists of adequate growing space for the root system, well-conditioned soil 16 inches to 24 inches deep, and sufficient water and oxygen. To check the water and soil condition of the root environment, dig a hole outside the drip line of the tree and determine if the soil is dry, wet or compacted. Soil moisture is adequate if the soil can be made into a ball with little pressure.