Q.Killing trees
Three plum trees in our yard died. We cut them down, added new soil to the area, and planted grass. Nothing will grow in a three foot circle where the trees were. Could they have been poisoned?
Certified GKH Gardening Expert
It could be a disease that affects multiple plants, salt or fertilizer buildup, some other toxic substance in the soil, or very poor drainage in that spot. You could try getting a soil analysis to see if that identifies any problem. You could also flush the soil with clean water to try to remove toxins:
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/reversing-soil-salinity.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/fertilizer-burn-in-gardens.htm
If both grass and plum trees die in the same spot, though, it's unlikely to be a disease.
https://garden.org/nga/searchqa/answer/38112/
https://www.gardeningknowhow.com/plant-problems/environmental/planting-in-old-spaces.htm
