What symptom might indicate a decline in trees infected by oak root fungus?

Mycelial fans at the base of trees represent a key visual symptom associated with oak root fungus infection, commonly known as Armillaria. This fungus specializes in decaying root systems and often manifests in recognizable mycelial structures that form at the base of infected trees. These fans, which resemble sheets or mats, indicate that the fungus is actively growing and colonizing the area, leading to a decline in overall tree health.

In contrast, healthy foliage, rapid growth, and budding flowers would typically signify that a tree is thriving and not suffering from an infection. These symptoms would not be indicative of any underlying problems linked to oak root fungus. Therefore, the presence of mycelial fans at the base of a tree serves as a clear warning sign of the detrimental effects of oak root fungus, making it an essential observation for diagnosing health issues in these trees.