Can Tangle Vine (Morning Glory) really be controlled?

Can you really control the growth and spread of Morning Glory?

Three years ago we had a Morning Glory hedge in front of our house. We put in this planter and I spent at least a half hour each morning pulling out the weeds, over and over again. I finally got smart and started spraying the weeds with a general weed killer. It helped, but each week I still had to pull the stupid Tangle Vine from in the middle of these grasses. The roots were so tight, I couldn't imagine how the weeds could grow there, but every week they were back. 

The next year was better. We put down a thin layer of bark mulch and applied a pre-emergent herbicide. The weeds were better, but still the defiant weeds would grow among and inside the grasses. Every week the weeds were back, over and over again. 

This year we got the three inches of bark mulch down and reapplied the pre-emergent herbicide. So what have I found week and week. This is it. This picture. I have not once pulled Morning Glory out of the inside of the grasses this year. Most weeks I have not found any weeds growing in between the plants. Only about once per month do I have to spray a tiny, little weed. So three years of bark mulch, established plants, pre-emergent herbicide, and continuing mechanical and chemical control have created a space with minimal weeds. Three years of continued application of a maintenance system have greatly controlled the growth and establishment of Tangle vine. So yes, you can control Morning Glory.