The symptoms are variable depending on the host infected, ranging from stunted leaves to chlorotic needles and dieback of twigs and branches.

The most effective ways of management focus on limiting the spread of the fungus, planting resistant species, and removing infected material.

Because this disease is caused by multiple species within the genus Armillaria, it has an extremely broad host range.

These include light or bleached wood as a result of the degradation of essential cell wall compounds such as lignin and hemicellulose.

Upon removal of the bark, white mycelial mats are visible along with rhizomorphs, a distinctive reproductive structure.

Rhizomorphs are string-like masses of hyphae utilized if no new hosts are nearby and spread by probing through the soil towards uninfected roots.

Armillaria can last up to 50 years in stumps of dead trees, infecting new hosts that come up nearby in that time period.

It can also kill healthy trees especially in dry areas, like coniferous forests in the western United States.

[6] Using collar excavation to expose primary roots directly below the crown to the continuous cycle of solar heating and air may reduce the colonization from Armillaria in trees that are already infected.

This disease poses a serious threat to the timber industry in that it affects nearly every cultivated species of hardwood and proves very difficult to remove once it has entered an area.

In fact, Armillaria is recognized as the largest living organism due to its clonal method of spreading.

Infection is especially strong where environmental conditions are optimal and a large amount of possible hosts exist.