https://phys.org/news/2018-10-epidemic-turf-herbicide-resistance-annual.html

"This is a landmark study bringing together weed scientists from across the United States to address the important issue of herbicide resistance in annual bluegrass. It is exciting for UTIA to be involved in an effort that will provide such comprehensive and valuable information to turfgrass managers," said Brosnan.

In Tennessee, turfgrass is big business, contributing $5.8 billion to the state's economy in 2013, the latest year for which measurements are available. In a survey of Tennessee turfgrass industry managers conducted by UTIA researchers including Brosnan, nearly all of the state's golf, sports field, lawn care and sod production professionals indicated that weed control was an important and problematic issue influencing the profitability of their businesses. Nationally, the turf industry has been valued to exceed $62 billion, but that figure dates to the mid 2000s in an industry that is notoriously difficult to quantify. Weeds, however, are everybody's problem.