I am looking for an effective way to kill Brazos Blackberries - I have them going in the middle of a beautiful wisteria and I am sick and tired of pulling every year - what a pain..... I have tried roundup concentrate on new growth - just turns the plant red and it continues, I have tried 912 herbicide - no effect. Does anyone know of a solution for blackberries that really works??? Please help (he said with scratched arms) Thanks!!