Useful links

Agricultural chemical resources

Crop Data Management Systems :: CDMS :: website for MSDS's and chemical labels
Greenbook :: website for MSDS's and chemical labels for many chemical companies

Federal Government

ANSTF :: Aquatic Nuisance Species Task Force
BLM Invasive and Noxious Weeds :: Bureau of Land Management
ETOXNET :: Extension Toxicology Network
FICMNEW :: Federal Interagency Committee for the Management of Noxious and Exotic Weeds
NAPIS Pest Tracker:: National Agricultural Pest Information System
U.S. Fish and Wildlife Service :: invasive species
USDA :: crop profiles
USDA :: Exotic and Invasive Weeds Research Unit
USDA :: plant health :: noxious weeds program

California

CDFA :: California Department of Food and Agriculture
CDFA :: California Department of Food and Agriculture :: Encycloweedia :: noxious weeds
DPR :: California Department of Pesticide Regulation
DPR :: California Department of Pesticide Regulation :: continuing education

Other states

Control of Invasive Exotic Plants in the Great Plains
Idaho One Plan :: pest management
Kansas Dept. of Agriculture :: plant protection and weed control program
Michigan Dept. of Agriculture :: prohibited and restricted weeds
North Dakota Dept. of Agriculture :: noxious weeds team

International

Australia :: Tropical and Subtropical Weeds Research Unit:: University of Queensland
Australia :: Weeds Australia:: an Australian Weeds Committee National Initiative
Australia :: Weed's News :: weed research and weed control and prevention information
Canadian Poisonous Plants Information System
Saskatchewan Agriculture and Food :: guidelines for control of weeds
Saskatchewan Agriculture and Food :: weed identification guide

Societies

APMS :: Aquatic Plant Management Society
Cal-IPC :: California Invasive Plant Council
CWSS :: California Weed Science Society
CWSS-SCM :: Canadian Weed Science Society
CIPM :: Center for Invasive Plant Management
CWMA :: Colorado Weed Management Association
IWSS :: International Weed Science Society
MAPMS :: Midwest Aquatic Plant Management Society
NAWMA :: North American Weed Management Association
NCWSS :: North Central Weed Science Society
NEWSS :: Northeastern Weed Science Society
SWSS :: Southern Weed Science Society
WAPMS :: Western Aquatic Plant Management Society
Weeds Gone Wild :: Alien Plant Invaders of Natural Areas
WSSA :: Weed Science Society of America
WSWS :: Western Society of Weed Science

University of California

UC ANR :: Agriculture and Natural Resources
UC ANR :: Cooperative Extension county offices (UCCE)
UC Davis :: Center for Plant Diversity (formerly known as the Herbarium)
UC Davis :: Dept. of Plant Sciences
UC IPM :: Statewide Integrated Pest Management Program
UC IPM :: Pest Notes (weeds and other unwanted plants)
UC Research and Information Centers (RICs)
UC Rice Research and Information Program
UC Riverside :: Dept. of Botany & Plant Sciences
UC Weed Science blog

Universities

Clemson University :: South Carolina weed science research
Colorado State University :: common weeds, weed control, noxious weeds
Iowa State University :: weed science
Kansas State University :: agronomy :: weed science
Kansas State University :: extension agronomy :: weed management
Louisiana State University :: weed science
Monash University :: Australia :: The Weed's News
New Mexico State University :: weed science
North Carolina State University :: weeds
North Dakota State University :: weeds and weed control
Oklahoma State University :: weed science
Oregon State University :: weed science
Penn State University :: weed management
Purdue University :: Indiana weed science
Rutgers University :: New Jersey weed gallery
Southern Illinois University :: weed science
Texas A&M :: broadleaf weeds
University of Florida :: Center for Aquatic and Invasive Plants
University of Georgia :: weed science
University of Illinois :: weed science
University of Maryland :: weed science
University of Massachusetts-Amherst :: vegetable program :: weed management
University of Missouri :: Delta Center weed science
University of Missouri-Columbia :: weed science program
University of Nebraska-Lincoln :: weed science
University of Wyoming :: weed identification
Virginia Tech :: weed identification guide
Washington State University :: Hortsense

Miscellaneous

Jepson Online Interchange :: California Floristics
The Plant List :: a working list of all plant species