Question
1.  We had several gumball trees cut down 2 years ago.  We still have little "trees" trying to grow all over the yard, apparently from roots left underground.  We just keep cutting them off.  What can we do to stop this permanently?

2.  I heard that maple trees in paticular have some aspect to them that will prevent a healthy garden if planted later in the same area.  Is this true?

Answer
1. Root systems of hardwood trees will sprout new plants. Spray the new sprouts with a herbicide called Roundup. The foliage will take up the herbicide and move it to the root system and kill the roots and the sprouting will stop. Roundup will kill any green plant it is put on so spray only when the wind is NOT blowing and keep the spray off any plant not wanting to be killed.
2. No maple tree do not prevent other plants from growing under them or where they were growing. Some plant do not do well in the shade and these will not grow well under the shade of a maple tree. But there is no chemical that the maple tree produces that will stop one from planting where a tree was removed.