A recent post in Hay & Forage Grower by Robin Newell argues that planting alfalfa is an excellent strategy to manage herbicide-resistant weeds.
Alfalfa offers a great opportunity to combat the spread of herbicide-resistant weed variants on your farm for two main reasons. First, alfalfa is a forage crop with multiple cuttings per year. The frequent harvest schedule for alfalfa greatly reduces the opportunity for weeds to thrive and produce viable seed. A disc mower or cutterbar does not discriminate between “normal” weeds versus weed variants that have developed resistance to various herbicide groups.
Secondly, alfalfa provides a good opportunity to rotate herbicides by applying different herbicide groups for weed control than you would normally apply to other crops in rotation. The practice of herbicide rotation can be used to break the cycle of herbicide-resistant weed selection brought on by repeated applications of the same herbicide group in the same fields.
You can read the full article here.