This 2,400 Year Old Mushroom Is The Largest Living Organism On The Planet

Armillaria root disease infects new hosts when uninfected roots of susceptible trees contact infected stumps or roots. The fungus grows across root contacts and invades the root tissues of new hosts. It is able to spread along both live and dead roots. Spread also occurs to a lesser extent by rhizomorphs, which can grow a few feet through soil to infect nearby host roots.