This being our sixth year really attacking those jokers. I can tell you that this spring spraying with crossbow/water. I only used a 1/2 of what I normally would and I only counted 13 "small" multi flora roses and they were in the middle of pastures, not in fence rows. So I guess the crossbow works but, has no residual. We are starting in on GRAZON P+D it supposed to last for three months at 3pts. to the acre so we shall see.