For more information on herbicides, as well as weed control practices and concerns, peruse the sites below.

Universities
California Weed Identification www.ipm.ucdavis.edu/PMG/weeds_common.html
University of Illinois — Weed Identification web.aces.uiuc.edu/weedid
Illinois Agricultural Pest Management Handbook ipm.uiuc.edu/publications
Southern Illinois University www.siu.edu/~weeds
Iowa State Weed Science www.weeds.iastate.edu
University of Maryland Weed Science www.agnr.umd.edu/users/weed
University of Minnesota Weed Science appliedweeds.coafes.umn.edu
University of Missouri Weed Science www.psu.missouri.edu/agronx/weeds
Missouri Weed Science For Field Scouting muextension.missouri.edu/explore/agguides/pests/ipm1007.htm
Montana State Center For Invasive Plant Mgt. www.weedcenter.org
University of Nebraska 2003 Weed Guide www.ianr.unl.edu/pubs
New Mexico State University Weed Science taipan.nmsu.edu/weeds
2002 North Carolina Ag Chemicals Manual ipm.ncsu.edu/agchem/agchem.html
North Dakota Weed Information www.ext.nodak.edu/extpubs/weeds.htm
Ohio State University Weed Control Guide ohioline.osu.edu/b789
Oklahoma State University Herbicides And Use www.agr.okstate.edu/soybeans/herbicides.htm
Purdue National Ag Pest Information System www.ceris.purdue.edu:80/napis
Rutgers University — Weed Images www.rce.rutgers.edu/weeds
Texas A&M — Broadleaf Weeds aggie-horticulture.tamu.edu/plantanswers/turf/publications/weed2.html
Virginia Tech Weed Identification Guide www.ppws.vt.edu/weedindex.htm
Organizations And Other Sources
CDMS — Herbicide Labels & MSDSes www.cdms.net
Herbicide Resistance Action Committee plantprotection.org/HRAC
Idaho Pest Management Links www.oneplan.org/Crop/1cPestM.htm
International Survey Of Herbicide-Resistant Weeds www.weedscience.org/in.asp
Kansas Ag Department Pest Identification Photos www.ks-agr.org/plantpest
North American Weed Management Association www.nawma.org
North Central Weed Science Society www.ncwss.org
Northeastern Weed Science Society www.ppws.vt.edu/newss/newss.htm
Southern Weed Science Society www.weedscience.msstate.edu/swss
Weed Science Society of America www.wssa.net