Kristen Obeid, OMAFRA Weed Specialist – Horticulture

Internet If you are trying to identify a weed, find the newest information on herbicide resistance and other emerging issues in weed management you need to visit

Provincial Weed Page:

Ontario Crop IPM: Know how and why it is important to scout and identify weeds, as well as diagnose herbicide injury.

Herbicide Symptomology Photo Repository (UC IPM): Identifying nontarget crop and ornamental plant damage from herbicides has become much easier, with the launch of this new online photo repository developed by using nearly a thousand photos of herbicide-damaged plants. The images are cataloged to show damage that can occur from 81 herbicides in more than 14 specific herbicide modes of action, applied in field to demonstrate the symptoms or when known herbicide spray has drifted onto the plant. Each image is characterized with the name of the plant, mode of action of the herbicide, and notes the specific symptoms of damage. Together these photos provide a comprehensive archive of UC Herbicide Symptomsdamage to over 120 different crops and ornamental plants by known herbicides, which users can easily compare with what they see in the field.

Herbicide Injury Symptoms in Tomatoes PPI and PRE Herbicides:

Herbicide Injury Symptoms in Tomatoes Postemergence Herbicides:

Weed Control in Tomatoes and Peppers:

Pest ManagerPest Manager:  Originally for corn, soybean and wheat herbicides (as Weed Pro 75), now (as Pest Manager) allows you to identify, map and find integrated management options for common weeds, insects and disease in corn, soybean and cereal crops in Ontario.

Weed Science Society of America:

Sprayers 101: Sprayers 101 describes best practices in the safe, efficient and effective operation of agricultural sprayers:

University of Guelph:

Weed Control Act Legislation:

Noxious Weed List:

Herbicide Resistant Weed Maps: Stay up-to-date on where herbicide resistant weeds have been identified in Ontario with maps and a searchable Master table of all herbicide resistant weed species in Ontario by County and Herbicide Group.


Weed ID Guide for Ontario Crops. 2017. To order or download:

Ontario Weeds, Publication 505, Ontario Ministry of Agriculture, Food and Rural Affairs, by Professor Jack Alex, University of Guelph, 1992. 304 pages.  $15.00. To order, call: 1-800-668-9938  or see Products and Services on website out of print.

Guide to Weed Control, Publication 75, Ontario Ministry of Agriculture, Food and Rural Affairs. $20.00 + tax. Visit ServiceOntario Publications website at: or call ServiceOntario Publications Contact Centre at: 1-800-668-9938 or OMAFRA Resource Centres.

Identification Guide to the Weeds of Quebec, Publication VT 007, by Claude Bouchard and Romain Neron, 1999, ISBN 2-89457-174-7, 264 pages.  To order:  Distribution de livres UNIVERS, 845, rue Marie-Victorin, Saint-Nicholas, Quebec, G7A 3S8, (418) 831-7474 or 1-800-859-7474; fax (418) 831-4021,,  $16 + S&H.  French version also available.

Weeds of Canada and the Northern United States, by France Royer and Richard Dickenson, University of Alberta Press and Lone Pine Publishing, 141 Athabasca Hall, Edmonton, Alberta, Canada T6G 2E8, paperback, 434 pages, 750 colour photographs and 150 line drawings, 1999, $29.95.

Weeds of the Northeast, by Richard H. Uva, Joseph C. Neal, and Joseph M. DiTomaso, Published by Comstock Publishing Associates/ Cornell University Press, Sage House, 512 East State Street, Ithaca, New York, 14850,  1997,  paperback, ISBN 0-8014-8334-4, 397 pages, includes 299 weeds.

Steel in the Field: A Farmer’s Guide to Weed Management Tools, edited by Greg Bowman, 1997. Discusses history of herbicide use and concurrent decline in knowledge about weed management tools. Describes techniques of using a variety of cultivation tools while minimizing erosion and soil compaction. Presents case studies of weed management systems used by farmers throughout U.S., including small and large farmers growing agronomic, horticultural and dryland crops. Includes detailed drawings and explanations of many tools, including hoes, cultivators, flamers and guidance systems. 128 pp. US$18. Sustainable Agriculture Publications, Hills Bldg., University of Vermont, Burlington, VT 05405-0082; phone (802) 656-0471; email Website:

Weed Seedling Guide, Alberta Agriculture, Food and Rural Development, 1996, 62 page booklet, spiral bound field guide with photos and descriptions of 50 seedling broadleaf and grassy weeds.

Common Weed Seedlings of The United States and Canada, produced by the Weed Society of America. Their web site is at

Common Weed Seedlings of the North Central States, NCRE Publication 607, by Andrew J. Chomas, James J. Kells and J. Boyd Carey, Dept. of Crop & Soil Science, Michigan State University, Bulletin Office, 10-B Ag. Hall, East Lansing Michigan, 48824-1039, (517) 355-0240, Email:, paperback, 21 pages, 1998, $2.00 US,

The Biology of Canadian Weeds, Publications 1693 & 1765, Edited and compiled by Gerald A. Mulligan, Communications Branch, Agriculture and Agrifood Canada, Ottawa K1A 0C7, 1979 & 1984, paperback, 380 & 415 pages.

The Biology of Canadian Weeds, Contributions 62 to 83, Edited and compiled by P. B. Cavers, Department of Biology, University of Western Ontario, London, Ontario, ©1995 by the Agriculture Institute of Canada, paperback, 338 pages.

The Biology of Canadian Weeds, Contributions 103 to 129, Edited and compiled by P. B. Cavers, Department of Biology, University of Western Ontario, London, Ontario, ©2005 by the Agriculture Institute of Canada, paperback, 516 pages.

Peterson Field Guide to Wildflowers by Roger Tory Peterson and Margaret McKenney. Available from most bookstores, this is a good pictorial guide to identification and includes some species not commonly found in agriculture but similarly may not include all agricultural weeds.

Weeds of California (and other Western States) Joseph DiTomaso and Evelyn A. Healy, ©2007. A 2-volume reference book is a practical, easy-to-use guide to the identification and biology of over 700 terrestrial weeds. Included are full descriptions, colour photographs, shortcut identification tables, and identification keys. University of California, Agriculture and Natural Resources, Publication 3488. Order from Communication Services, 6701 San Pablo avenue, 2nd Floor, Oakland California 94608-1239. 1-800-994-8849,

And more

Videos: visit You Tube for weed management and identification videos.

Courses: Ontario Pesticide Education Program.

Weed Apps: Pest Manager App. Also, search the internet for the newest weed apps.

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1 comment on “Resources on weed management

  1. Kristy Grigg-McGuffin

    Reblogged this on ONfruit.

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