Through exposure over time to herbicides, some weeds can become resistant to the modes of action of particular herbicides. These weeds can thrive, spread and dominate if other weeds are controlled and provide no competition to resistant ones.
Dr. Daugovish has provided some guidelines for managing herbicide-resistant weeds and avoiding practices that can allow them to proliferate. These include identifying the weed species, using mechanical weed removal methods, getting them early, and monitoring the herbicide efficacy after application.
If you are interested in learning more about this, please see the entire article here. You can visit the Farm Bureau website at http://www.farmbureauvc.com/.