Phytophtera root rot is a fungal pathogen that affects many types of trees and plants. It is a soil-borne disease found on living roots that can survive for long periods of time without a host. Most often, Phytophtera is found on sites with poor draining soil and/or excessive irrigation. Symptoms of this disease vary depending on the plant species and may go undetected for many years. Small leaves, shoot dieback, overall crown thinning, chlorosis of the leaves, sap staining on the trunk and death can be signs there is a root rot problem. Diseased roots are sometimes black, break apart easily, have a pungent rotting smell and lack small, fine roots. Although not always black, typically the affected root will be discolored. Treatment by a commercial grade fungicide to the affected plant and surrounding plants is recommended by a tree care company. Sometimes repeat treatments are needed to eradicate the problem. It’s best to keep the site well drained by 1) planting appropriate plants/trees for the site that prefer wetter soil 2) add mulch, always keeping away from the trunk 3) french drains or natural soil berms to divert rainwater are recommended in certain situations of excessive surface water.
When a root rot problem is suspected, have a certified arborist inspect the plant’s roots for signs of infection. Sometimes a more in depth root collar excavation is needed on the overall root system for diagnosis to determine the extent of the disease. After diagnosis, treatment with a fungicide may be recommended as well as possibly changing the overall site’s soil drainage. In some cases, the affected plant or tree may need removal if the disease has advanced beyond treatment.