Hope it's ok to bump an old thread.
I planted a row of butternut along the road a year ago on 20' centers.
Deciding to hedge my bets so that the tree line doesn't look god awful in 20 years (in case they succumb to butternut canker). Planning on putting American Persimmon in between. Curious if anyone else has Persimmon and Juglone together.
Another aside, I have American Persimmon that grew 7-8 feet this year out of tubes. These are well mulched with no weed competition. The persimmon that just get mowed and no mulch only grew 1-2 feet this year. One of the biggest lessons I have learned is that nothing matters as much as weed control.