I think I’ll give the herbicide a try. I’ll go visit the dealer next time I’m up there. Lots of autumn Olive and black berry briars back there. Along with the poison ivy. Ha
I have had excellent success (100% kill rate) on my poison ivy using Crossbow and a little bit of the matching surfactant. I just looked up the product label, and blackberry is also readily controlled by Crossbow.
I have no clue on the Autumn Olive. I don't recall ever seeing it specifically listed on a herbicide label. I don't believe it is even a true Olive. I would suspect the Crossbow will work on it. (Non-expert opinion, but I don't think there is any harm in test spraying it.)
Further, the Crossbow is selective to woody plants and broadleaf weeds. I have sprayed poison ivy in my prairie grass and not harmed the grass at all. If you use it to control your nasty plants, the grass will survive to maintain your erosion control.
P.S. My county Noxious Weed department sells herbicides to landowners in the county at their cost - which is much cheaper than retail. I can also ask the department head questions when I have very difficult invasive species to eradicate. You might check to see if a similar resource is available to you.
