Forestry: I just found that the root of my big ginkgo tree has thickened and a tumor has grown. Cut it open to see if it's dark. It seems to have rotted. What is the reason, experts?

Hello! "The roots of the big ginkgo tree have thickened and a big tumor has grown. When I opened it, it was dark and seemed to have rotted. " Prove that your ginkgo tree has been in existence for decades and its roots are deep. This may be caused by two reasons. 1. There is a stone under the root of Ginkgo biloba, which prevents the upper root or bark from being damaged and infected. You can pour some 10% lime water into the cut tumor to kill insects and sterilize. 2. There are parasites in the root soil (dig the soil to see if there are "nematodes"). First, some carbofuran granules can be sprinkled for shallow tillage control, and some 10% lime water can be poured into the cut tumor to kill insects.