Speakers at the seminar will try to unlock secrets of underground reactions between fungi and trees and what are the best conditions for health.
The event - Trees, Roots, Fungi, Soil - Below-ground Ecosystems and Implications for Tree Health - will focus on tree-root pathogens, mycorrhizal fungi and saprotrophs at the National Museum in Cardiff.
Cardiff University School of Biosciences has teamed up with Bristol-based consultancy Treework Environmental Practice (TEP) for the event on 13 November.
Organised in association with the Arboricultural Association, will also examine soil amelioration and what leads to breakdown in functioning soil ecology, said a representative for the organisers.
"We will explore what constitutes a healthy environment where trees can grow and the different ways of addressing adverse impacts on functioning root activity," said a representative for the seminar.
Speakers include Dr Lee Klinger, an oak specialist based in California, who said: "I will attempt to tell the larger story of oak mortality in California."