Kretzschmaria Deusta, or That Black Rot at the bottom of Your Hackberry Tree
As an arborist working in and around Dallas, I see Hackberry trees on a daily basis. Lots of them. It’s actually a testament to their species that there are so many, since I’ve never heard of anyone intentionally planting one. But they’re everywhere, nonetheless, especially along fence lines in older neighborhoods. While they don’t last forever, and aren’t beloved by many people, they are fine trees, especially while they’re young.
Hackberries do encounter one serious problem, however: a rot called Kretzschmaria Deusta, formerly Ustulina Deusta. (I don’t count mistletoe because it’s easily controlled and not a health concern if removed at intervals.) Kretzchmaria is an untreatable rot that is common on hackberries in the south and frequently shows up on the base of the trunk, although it can form on openings higher on the trunk as well, such as low joints. The current fruiting bodies are white, and turn gray over time, sometimes oozing droplets of amber. The old fruiting bodies from seasons past are black and dried, and look almost as if someone charred a marshmallow and poured it on the base of the trunk.
Kretzschmaria is a serious rot, and cause for fairly immediate removal. It frequently causes basal failure, or in other words it’s the reason some Hackberries fall completely over. Sometimes you can actually see the progression of the rot through the root system by looking at the canopy, with some branches lush and others nearly defoliated. But Kretzschmaria can easily cause a tree to fall with no such warning, and there may be no signs of ill health at all besides this rot.
My experience is largely as a residential arborist, working in yards where trees rarely have enough space to fall without hitting something the trees’ owner cares about. As such, I always recommend removal when I see Kretzschmaria Deusta (and stump grinding afterward to remove all habitat for the rot to continue growing, especially if other hackberries are nearby). Better safe than sorry!