Certified GKH Gardening Expert
You will have to remove their food source. Armillaria are persistent and killing the fruiting mass is only superficial. Killing the mycelial mass is necessary. This is quite difficult, bordering impossible.
For this reason, it will have to run its course.
Removing the trees (and their roots) will remove the fungus, but if they are, indeed, Armillaria then it can be a treat in disguise! Unless you have had the mushroom professionally identified I would not consume them. If you know for certain, WITHOUT A DOUBT that they are armillaria... They make a wonderful addition to a meal.
If you can't say this with certainty, don't consume anything that you can't ID down to 100%
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