OK, maybe its a stupid question, but I'll ask it anyway!
Another case of a neighbor's tree causing a nuisance: sweet gum balls
all over (a part) of my father's lawn. Other than being a nuisance,
they are a tripping hazard for someone who is not as nimble on his
feet as he once was. Is there a spay, or other hormone treatment that
would cause the tree to not produce the balls? He has considered
asking the neighbor to do a little selective pruning, which may lessen
the problem a bit, but it seems that if we can create seedless fruits,
(I know, stopping seed production is probably easier that stopping
fruit production), there may be a hormone that could prevent sweet gum
trees from producing their spikey little caltrops.