Bermuda grass is a popular choice for lawns and athletic fields in the warmer climates of the U.S. But it can become an aggressive, hard-to-control weed in cool season lawns. "We find it's quite invasive in cool season lawns," said Brad Fresenburg, turf specialist for University of Missouri Extension. “It can be a blemish in a cool season tall fescue or Kentucky bluegrass lawn.”

Up until now, there haven't been many options for controlling it. But recently, at a University of Missouri Turfgrass & Ornamental Field Day, a new herbicide looked promising. "We've got a new one that just came out this year from BASF Corporation, called Pylex," Fresenburg said. "It's a post-emergent broadleaf and grass herbicide. The active ingredient is topramezone.”

Pylex can be used on cool season grasses like tall fescue, Kentucky bluegrass and ryegrass. "For the most part, it is safe to use on your lawn. You may, however, notice a slight amount of yellowing from this product," he said. “We’ve had some products in the past that do provide some selective control, but they’ve never been one hundred percent.”

Bermuda grass tends to grow lower to the ground and has more of a yellow/green color. It has runners, or stolons, that spread across the soil surface. Of the warm season grasses, it's the most aggressive and can spread six to eight feet per year. "But how to control it in cool season grasses is one of the most frequent questions I get," said Fresenburg.