Ditch weed is another name for HEMP, which has no THC to speak of. A guy that I knew in college was from Ohio, Ind., Ill. or one of those God forsaken Midwestern states on the wrong side of the Ohio River. During WW1 farmers in that area grew lots of hemp, and some of it escaped into the wild. Now the stuff grows in the ditches and the county road depts. have to send out men and equipment to spray and cut the stuff back. My friend told me that every-so often some students from one of the local colleges and universities would spot a stand of ditch weed and harvest it, and save the county money. He said that the locals got a kick out of seeing those college boys and girls working in the hot sun, only to find out that they couldn't get high if they smoked their entire haul. Smoke inhalation is not the same as getting high!
Many years ago a county deputy was patrolling on a gravel road. He stopped to watch some teen-agers in the ditch. When the kids saw him they sheepishly left the ditch and approached him saying he had caught them red handed, fair and square. The deputy looked at them and asked what they were talking about. The teen-agers said they were harvesting M.J. from the ditch. The deputy was HIGHLY amused. seems the M.J. they were cutting was really what I grew up calling horse weed, giant ragweed. City folk.
I actually saw a bunch of that on the side of the road back in '99 when I was making a trip to Sturgis, S. Dakota ,,, can't remember which state it was in either .