Notes:
Glyphosate resistant horseweed in the U.S. was first discovered in Delaware in 2000. Since that time, resistant populations have been identified in 11 other states (12 total).

Glyphosate Resistant Horseweed in US (confirmed in 12 states)<BR>DE (2000) <BR>TN (2001) <BR>IN (2002) <BR>MD (2002) <BR>NJ (2002) <BR>OH (2002) <BR>AK (2003) <BR>MS (2003) <BR>NC (2003) <BR>OH (2003) <BR>PA (2003) <BR>CA (2005)<BR>Horseweed pictures from SWSS Weed ID Guide<BR>