Post-emergent Herbicides For Roadside Flowers   The bad news is that there are few products that will selectively remove broadleaves from roadside flowers. The good news is that there are several products that will remove grasses from flowers. Plateau herbicide can be used as a post-emergent broadleaf and grass herbicide with a variety of roadside flowers after the flowers are established. This is a growth regulator, thus temperature and soil moisture can influence the effect of this chemical. Stunting of roadside flowers may occur. Measure the chemical precisely to avoid problems. We suggest that roadside managers use this chemical with caution until they have a better feel for the chemicals potential effects. More information can be found at prairiesource.com/pages/plateau Grass herbicides - these must be applied when the grass weeds are young and no taller than 4 inches Poast II - grass herbicide - sithoxydim Grass-be-gon - grass herbicide - fluazifop Horizon - grass herbicide - fenoxaprop