Hi, I am the president of the garden club at the University of Maryland, Baltimore County (UMBC). Our raised beds that we use for growing vegetables, fruits, and herbs are becoming invaded by wire grass. I was wondering if you had recommendations for cheap (we're college students) ways to effectively rid our plots of this aggressive grass. Thank you!
Bermudagrass is one of the most challenging perennial weed grasses because of the stored energy in its roots which make it able to recover and surge again.
If it came from the turf surrounding the raised beds, we'd recommend creating a barren strip around each raised bed to keep it back. Kill everything with glyphosate and cover the soil with commercial-grade heavy landscape fabric pinned right up to the base of the raised bed. This will be about 3 feet wide around the beds. (You can buy it in a roll. You may have to call around to find it. Don't use the light weight stuff from a big box store.) Use commercial grade because it will last for years and does not require covering with mulch. (If you put mulch over landscape fabric, the Bermudagrass will simply grow on top of the fabric in the mulch.)
Within the beds, you can remove it manually, being sure to get every bit of root. There are also herbicides with glyphosate labeled for use in vegetable gardens that will kill Bermudagrass. Two applications late in the season, spaced 2-3 weeks apart, are most effective. Target it carefully only on the Bermudagrass foliage.
Glyphosate is a systemic herbicide, meaning that it is absorbed into the system of the plant and will go down into the roots--the biggest hurdle with Bermudagrass. As with any tough perennial weed, best time to spray a systemic is late in the active growing period (for Bermudagrass this is late summer), when the plant is transporting carbs down to the roots for winter, pulling the herbicide with it most efficiently. Spray twice.
Read through our page on Bermudagrass control, plus the links: https://extension.umd.edu/hgic/topics/bermudagrass
Don't hesitate to ask any further questions.