ENVS*4190 Biological Activity of Herbicides

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The following description is for the course offering in Winter 2023 and is subject to change. It is provided for information only. The course outline distributed to the class at the beginning of the semester describes the course content and delivery, and defines the methods and criteria to be used in establishing the final grades for the course. Offered in odd-numbered years.

This course explores the diverse modes of action of botanical, microbial and synthetic herbicides. Detoxification mechanisms, selectivity, resistance management and the process of herbicide discovery and development are also considered. The course includes a review of plant physiological systems and discussion of the stability and distribution of herbicides in the environment.

In this course we will explore the reasons we are using molecules as weed control agents. The rationale for chemical weed control will be explored. The history and discovery process of herbicides will be presented. For every herbicide group, the target site inhibition, metabolic pathways, translocation pattern, selectivity, soil behaviour and basic chemistry will be presented.

Pre-Requisites: Minimum of 12.00 credits
Restrictions: ENVB*4240. Registration in the BAS, BBRM, BSC, BSC(Agr) or BSC(Env) program.



Teaching Assistant:


Credit Weight:


Course Level:

  • Undergraduate

Academic Department (or campus):

Plant Agriculture



Semester Offering:

  • Winter

Class Schedule and Location:

Please refer to WebAdvisor for class schedule and location.

Learning outcomes:

At the end of this course, students should be able to:

  1. Identify the need for chemical control of weeds in the global context of preservation of food, fiber and fuel production.
  2. Classify and compare the most currently used herbicides based on chemical structure, mode of action, usage and environmental fate.
  3. Identify and discuss the specific physiological processes targeted by herbicides.
  4. Relate, with specific examples, the molecular targets of herbicides to the symptoms they cause at the whole plant level.
  5. Determine how absorption, translocation and detoxification of herbicides relate to their mode of action.
  6. Explain the steps in herbicide discovery and development and how they compare to those of other chemicals such as drugs or pesticides.
  7. Explain how selectivity is attained and how it relates to chemistry, physiology and environmental conditions.
  8. Describe the conditions leading to herbicide resistance in weeds and how this phenomenon can be prevented or managed.

Lecture Content:

  • Herbicide discovery and development
  • Regulatory framework around herbicides
  • Herbicide formulation and application
  • Absorption, translocation and detoxification of herbicides.
  • Selectivity of herbicide
  • Target sites and chemical families
Labs & Seminars:

There are no labs or seminars scheduled for this course.

Course Assignments and Tests:

Assignment or Test Contribution to Final Mark (%) Learning Outcomes Assessed

Online Quiz 1


1, 2, 3, 4, 5, 6



1, 2, 3, 4, 5, 6

Online Quiz 2


2, 3, 4, 5, 7

Online Quiz 3


2, 3, 4, 7

Final Exam


2, 3, 4, 7, 8

Additional Notes:

Online quizzes will be open for a short time and be multiple-choice. Their aim is to help prepare for the assignments. The assignments will be take-home and will require thorough review of the material. They will help with midterm and final exams.

Final examination:

Please refer to WebAdvisor for exam schedule and location.

Course Resources:

Required Texts:


Recommended Texts:


Lab Manual:


Additional Resources:
  • Additional material will be made available on CourseLink as required. 
  • Course material will be available on Courselink prior to each lecture and will be in Power Point and PDF formats.
Field Trips:


Additional Costs:


Course Policies:

Grading Policies:

Policy on Late Assignments: Answers to all take-home assignments are due at the beginning of class on the dates specified. A penalty of 10% per day will be deducted for late assignments. Requests for extensions due to illness or other personal issues must be made in writing and accompanied by appropriate supporting documentation.

Re-evaluation: Students have 5 class-days upon receiving assignments to appeal to the instructor. The entire assignment will be re-evaluated for accuracy of grading.

Course Policy on Group Work:


Course Policy regarding use of electronic devices and recording of lectures:

Presentations that are made in relation to course work - including lectures - cannot be recorded or copied without the permission of the presenter, whether the instructor, a student, or guest lecturer. Material recorded with permission is restricted to use for that course unless further permission is granted.

Other Course Information:

University Policies

Academic Consideration

When you find yourself unable to meet an in-course requirement because of illness or compassionate reasons, please advise the course instructor in writing, with your name, id#, and e-mail contact. See the academic calendar for information on regulations and procedures for Academic Consideration:

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The Academic Misconduct Policy is detailed in the University Calenders:


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