PLSC 753 - Action and Fate of Herbicides
Department of Plant Sciences, NDSU
Spring 2008

Instructor:
Dr. Kirk Howatt
470-F Loftsgard Hall
office hours: 8-12 MWF
phone: 1-7209
E-mail: kirk.howatt@ndsu.edu

Course Description:

This course will examine pathways of herbicide entry into the plant and physiological responses to major herbicide modes of action.

Prerequisites:

PLSC 323, PLSC 453/653 preferred, BOT 380 and CHEM 240 and 260 helpful.

Course Objectives:

  1. To increase understanding of chemical processes regulating herbicide movement and partitioning in soil, water, and plant tissue.
  2. To increase understanding of herbicide metabolism in plants.
  3. To increase understanding of symptomology related to major herbicide modes of action.
  4. To increase understanding of physiological action of major herbicide modes of action.

Lecture Topics:

  I Introduction  
  II Herbicide Absorption and Translocation  
    a. Foliar  
    b. Root and shoot  
  III. Herbicide Metabolism  
    a. Fate in plants  
    b. Bio-activation  
    c. Pathways of metabolism  
  IV. Herbicide Classification by Mode of Action  
    a. Growth regulators  
    b. Photosynthesis inhibitors  
    c. Pigment inhibitors  
    d. Cell membrane disruptors  
    e. Mitosis inhibitors  
    f. Amino acid inhibitors  
    g. Acc-ase inhibitors  
  V. Safeners  
  VI. Adjuvants  

Lecture Reference: Physiology of Herbicide Action. © 1993. M. Devine, S. Duke, and C. Fedtke. PTR Prentice Hall, 441 pp. Some animations are available online through the Western Society of Weed Science lessons link www.wsweedscience.org

Lectures: Loftsgard 102, 1:00 - 1:50 p.m., M/W/F

Grading Structure:
Reading Log and Class Participation 15 pts
Metabolism Focus Paper/Presentation 35 pts
Exam I 100 pts
Exam II 125 pts
Exam III 125 pts
Comprehensive Final Optional

Make-up of missed examinations should be scheduled as soon as the conflict is known. Final exam score will be an oral format and provide the opportunity to increase the earned grade by one letter grade.

Each student will prepare log of reviewed literature (Journal articles) in preparation for class discussion on the modes of action. An electronic file will be acceptable. Each student should read a minimum of two articles before each of the major modes of action identified under section four of lecture topics are discussed with the class (2X7=14 articles minimum). The log will contain the source, presented in Weed Science format, followed by one or two words to describe the article's usefulness in explaining the mode of action. A brief summary will be expected that explains findings pertaining to mode of action. Each entry in total does not need to be more than half of a page.

Each student will prepare a short paper describing the technical and chemical properties of an herbicide introduced within the last few years. The paper should include chemical properties and how these relate to behavior in the environment and plants. Information could include pathway reactions, time course, fate of metabolites, evidence for selectivity or use patterns. Length is not mandated. Please use 10 or 12 pt Arial font, 1-inch page margins, and 1.5 line spacing. Students will present information in class.

Course Grading:

Expectations will not exceed those provided below.
92% and above - A
82% to 90% - B
below 82% - C

Students with Disabilities are asked to inform the instructor so that arrangements can be made in cooperation with the Office of Disability Services to provide appropriate services.

The Honor Code will be followed in this course. Examinations are given according to the policies of the Honor System within the College of Agriculture (http://www.ag.ndsu.nodak.edu/colag/honor.htm). University Guidelines for academic honesty are outlined in NDSU University Senate Policy, Section 335: Code of Academic Responsibility and Conduct (http://www.ndsu.nodak.edu/policy/335.htm).

Tentative Lecture Schedule:

January 9 - Introduction
11 - Chemical properties
14 - Chemical properties
16 - Absorption
18 - Absorption
21 - MLK Holiday
23 - Translocation
25 - Translocation
28 - Metabolism
30 - Metabolism
February 1 - Metabolism
  4 - Exam 1
6 - Growth regulators
8 - Growth regulators
11 - Photosynthetic inhibitors
13 - Photosynthetic inhibitors
15 - Photosynthetic inhibitors
18 - Presidents Day Holiday
20 - Pigment inhibitors
22 - Pigment inhibitors
25 - Pigment inhibitors
27 - Membrane disruptors
29 - Membrane disruptors
March 3-7 - Spring Break
  10-13 - WSWS meeting, Student Presentations
14 - Exam II
17 - Mitosis inhibitors
19 - Mitosis inhibitors
21 - Amino acid synthesis inhibitors
24 - Amino acid synthesis inhibitors
26 - Amino acid synthesis inhibitors
28 - Amino acid synthesis inhibitors
31 - Acc-ase inhibitors
April 2 - Acc-ase inhibitors
4 - Miscellaneous
7 - Safeners
9 - Adjuvants
11 - Exam III
  14 - Topic Discussion