Annosus Root Rot: Everything You Need to Know

Diagnosing plant diseases can be difficult, especially if you are not trained in detecting the signs and symptoms of the disease. For homeowners with conifer species such as fir, spruce, and pine trees on their property, one particular tree disease can be essential to understand: annosus root rot. 

If you are unsure about diagnosing annosus root rot on any coniferous trees on your property, you need help from the best tree service company in Annandale, VA. At G&V Tree Service, our experienced team of certified arborists is happy to provide a wide array of tree care services, from disease identification to disease management, and even tree removal. 

What Is Annosus Root Rot?

Annosus root rot, also known as annosum root rot, is a disease caused by the fungus Heterobasidion annosum. It is common in temperate areas and can affect trees in both forest and urban settings. Annosus root rot is one of the most destructive fungal diseases in conifers. If left untreated, it can cost around $35 million annually in large areas as the disease can spread quickly and easily.

Which Species Are Susceptible to Annosus Root Rot?

Generally, this fungal disease targets pine trees, but can also be found in fir and spruce trees. The white fir is the most common species, but it can also affect other species such as Douglas fir, Engelmann spruce, subalpine fir, and blue spruce.

Signs and Symptoms of Annosus Root Rot?

Infected trees grow fungal fruiting bodies known as basidiocarps on their trunks. These bodies are dark brown with a white margin. You can usually find these fruiting bodies during late spring to early summer when conditions are moist and warm, optimal growing conditions for fungal diseases. 

Once matured, these fruiting bodies burst and release conidiospores, the asexual reproductive structures of fungi. These spores are carried by wind or insects to nearby trees, allowing new infections to take hold. 

H. annosum spores are common in the soil and root system of trees in the northern hemisphere and can lie dormant in the ground for up to several years. Once the fungus in the soil makes root contact with the system of a susceptible tree, the spores penetrate the outer woody layer and colonize the interior.

Infected trees can be identified by the fruiting bodies that are initially found on the base of the tree trunk. The bark changes color from a dark brown to a pale yellow as the infection worsens. Afterward, the bark color changes from yellow to white with irregular black specks.

You may also notice resin flowing from the tree’s base as the infection progresses and the healthy tissue slowly dies. At this point, it’s too late to reverse the condition, and infected trees will die.

How to Prevent Annosus Root Rot?

The best thing to do to prevent annosus root rot in a landscape setting is to choose species that are resistant to the disease such as true firs and Western larches. If you already have susceptible species growing on your property, you can opt for prophylactic stump treatments to prevent disease progression. 

Remove any trees already infected with annosus root rot completely. Even a freshly cut stump can provide a host for the disease, allowing it to infect nearby healthy trees.  

Protect Your Conifer Trees 

Preventing an outbreak of annosus root rot among susceptible trees on your property is often a pre-emptive strike. However, if the damage has already been done, you should remove any infected tree to preserve healthy ones.

Learn more about uprooted trees and how to remove them properly. Call G&V Tree Service in Annandale, VA, and schedule a consultation for annosus root rot today at 703-337-3080.