The first step to controlling weeds is proper identification. There are many resources available to help with identification.
Virginia Tech's Weed Identification Website and App
Virginia Weed Identification Clinic: Farmers and homeowners can also submit samples to the through their county extension agent.
Find your agent: https://ext.vt.edu/offices.html
For agents: Virginia Weed ID Clinic
Virginia Weed ID Clinic Instructions (for agents)
Other online identification tools include:
University of Missouri Weed ID Guide
North Carolina State University Turf Files
The Ohio State University Annual and Biennial Weed Guide
The Pennsylvania State University Center for Turfgrass Weed Science Plant ID
University of Delaware Vegetative Grass Key
University of Delaware Broadleaf Identification Key
The University of Tennessee has a fee-based identification service that offers both traditional identification by botanical characteristics and molecular weed identification.