Since I began a career in weed science over 20 years ago, my three "go to" weed identification books have been Ontario Weeds, Weeds of Quebec and Weeds of the NorthEast. In the mid 2000s, Peter Smith and I wrote a small weed ID guide: A field guide to grassy and broadleaf weeds mainly so that we could experiment with macro photography and a section called I know it’s not … because where we could spell out the specific characteristics that made a plant different from similar looking species. That section was well received by farmers, agronomists and aspiring weed scientists. So for the Weed ID Guide for Ontario Field Crops François, Jocelyne and I have tried to take the best of all those guides and create what we hope is a comprehensive field guide to easy weed identification.

This book is for people who work in agriculture and are hoping to minimize the impact that weeds have on their crops. There are literally hundreds of other species we could have included in this book, but we wanted to focus on species that are commonly found in agricultural areas or that are common in Ontario and may pose a risk to human health (such as rashes and blisters caused by giant hogweed or wild parsnip). Perhaps one day, a “Volume Two” will be created that has more species, but for now this should cover most of your needs.

If you’re a plant taxonomist, please accept my apologies, we’ve taken many liberties with describing different plant species in this book at the expensive of, undoubtedly, technical accuracy. I have great respect for those trained in the classification of plants and the attention to detail that it requires. I would hope that this book sparks an interest in some to pursue plant taxonomy so that in another 20 years they can write a better, more accessible and technically accurate book then this one.

A special acknowledgement to Peter Smith and Annalee Winter who were instrumental in making this field guide a reality. Peter is a good friend, a hard worker and a talented photographer who has made many behind the scenes contributions to Ontario Agriculture. Annalee worked as a summer assistant with me for two seasons and laid the foundation for many of the weed profiles in this guide. I cannot say enough good things about Annalee, she is an impressive and remarkable person.

Mike Cowbrough

About the authors

Mike Cowbrough

Growing up on a beef and crop farm, Mike aspired to be a professional football or rugby player. Unfortunately there was not a great demand for 5'7" players of average skill in either sport so he decided to pursue a career in weed science instead. A graduate of the University of Guelph (BSc., 1998 and MSc., 2001) Mike began his career in the Crop Protection Industry and then in 2002 moved to his current role as weed specialist (field crops) with the Ontario Ministry of Agriculture, Food and Rural Affairs. He is the recipient of the 2009 Award for Excellence in Weed Science Extension presented by the Canadian Weed Science Society and the 2012 T.R. Hilliard Award for Agriculture Extension presented by the Ontario Agriculture College.

François Tardif

François is a Professor in the Department of Plant Agriculture, University of Guelph. His research programs focus on weed management and weed biology in field crops and turf. One emphasis of his program is the understanding of herbicide resistance in weeds, so as to develop better resistance management strategies. Dr. Tardif received his BSc., MSc. and PhD. from Laval University in Québec City, Québec, Canada, where he specialized in crop production and weed science. After completion of his studies, he went on to work in Adelaide, Australia to specialize in herbicide resistance. Dr. Tardif has been at the University of Guelph since 1996 where he has taught weed science to graduate, undergraduate and diploma students and supervised MSc. and PhD. students.

Jocelyne Letarte

Jocelyne was raised in a small town just outside of Québec City. Surrounded by farmlands, one of Jocelyne’s fondest memories with plants was riding her bike in the early days of summer to look for the best patch of wild strawberries and bring back home her precious harvest to eat with fresh cream and a “soupçon” of maple syrup. Later on, as a young adult, she received a BSc. in biochemistry at Laval University and then, decided to pursue graduate studies and obtained her MSc. in biochemistry-immunology at the same university. With a desire to travel, she accepted a PhD. scholarship offer from the University of Adelaide in Australia and earned her doctorate in plant molecular biology. Nowadays, she is still involved in the world of plants and works as a Research Associate at the University of Guelph in the department of Plant Agriculture. Her pleasure of berry picking has never left her and every summer she now brings her daughters and husband in tow for a bit of PYO and fun while exploring Ontario beautiful farmlands.

Photo Credits: Peter Smith, Mike Cowbrough, Annalee Winter, Meghan Grguric, Leanne Freitag, Darren Robinson, Mike Veenema, Christy Shropshire, Michelle Arsenault,, and Doug Richards.