We have two plum trees very badly infected with black knot. We are going to have to cut them down and want to replace them with red horse chestnuts, which will be planted in the same area. Does this disease go into the ground? Will it infect horse chestnut trees? These will be planted on a church property so they don't get the care they would on a private property.
Black Knot Disease
Certified GKH Gardening Expert
Are you sure the trees are goners? This article can help make that determination and offer fixes for the black knot issue: https://www.gardeningknowhow.com/edible/fruits/plum/black-knot-tree-disease.htm
Though I don't believe black knot affect horse chestnuts, the fact that this is a fungus means there will be spores in the ground (which can spread to other areas) where you intend to replace the trees. To avoid any future issues with replant disease, this article should help: https://www.gardeningknowhow.com/plant-problems/environmental/planting-in-old-spaces.htm