Jeff from Elba, Al writes
I have 200 blackberry plants that have been overtaken by dog fennel.
Unfortunately there is not a chemical that we are aware of that would kill the dogfennel and not also kill the blackberry plants. Ã‚ You could use a glyphosate based product, but care should be taken to not spray the blackberry plants as they could also be killed.
Answer last updated on: 02/03/2016