How To Eradicate Honey Fungus

Question

Honey fungus has already killed an old hornbeam an oak tree 30 metres of conifer hedge and an apple tre.

Answer 1

Unfortunately, Armillaria does not have a treatment. Removal of all infected materials, and antifungal agents will help to kill off any remaining specimen.

https://www.gardeningknowhow.com/plant-problems/disease/armillaria-root-rot-control.htm