Can you tell us about your site? Are the weeds in your lawn/landscape, pasture, or some other area? Rezilon is registered only for pastures, not home lawns, so it is illegal to apply it to a lawn. 

My wife is wanting a horse back on it, she wants the thorns out of the grass. We've always had a few but the heat and dry summers the last couple of seasons has allowed them to propagate in about an acre area. We live rural so "yard" is vague description of the area. Hope that helps. 

I can give you recommmendations for home turf/lawns but if there are animals such as horses on it you should probably treat it more as a pasture type situation because herbicides and rates will be different. Either way, encouraging your deisrable grass, which I assume is bermudagrass, to be more vigorous by proper fertilization and irrigation can help choke out weeds. To come up with a plan that may include herbicide applications for your particular situation I encourage you to reach out to the Seminole County OSU Extension Center for assistance. 

https://extension.okstate.edu/county/seminole/