Agronomy and Horticulture Department
Appearance of Herbicide Resistance in a Weed Population
Date of this Version
Plant and Soil Sciences eLibrary (PASSeL) Lessons.
A contribution of Kansas State University and the University of Nebraska Cooperative Extension. Journal series no. 1025.
Through the repeated use of the same herbicide, weed populations can consist of susceptible (S)-biotypes that are controlled and herbicide resistant (R)-biotypes that are left behind to produce and return seed with the resistance characteristic back into the soil. This lesson will highlight the population dynamics of a mixed weed population, containing S- and R-biotypes, and compare and contrast the rate at which herbicide resistant weeds appear in a population under a diversity of selection pressures. This lesson will highlight the population dynamics of a mixed (herbicide susceptible and resistant biotype) weed population, and compare and contrast the rate of appearance of herbicide resistance in a mixed population under a diversity of selection pressures.
At the completion of this lesson, students will:
1. Understand the differences between susceptible, tolerant, and resistant weed populations.
2. Describe diagrammatically and mathematically, the dynamics of an annual weed species population composed of S- and R-biotypes.
3. Describe herbicide characteristics, aspects of weed species biology, and management practices that alter intensity of selection pressure and impact the rate at which herbicide resistance appears in a weed population.
4. Devise a weed management plan with a diversity of selection pressures to reduce the rate at which herbicide resistance appears.
Copyright 2005, the authors. Used by permission.
JNRLSE approved, 2005.
This project was supported in part by the National Research Initiative Competitive Grants CAP project 2011-68002-30029 from the USDA National Institute of Food and Agriculture, administered by the University of California-Davis and by the National Science Foundation (NSF), Division of Undergraduate Education, National SMETE Digital Library Program, Award #0938034, administered by the University of Nebraska. Any opinions, findings, conclusions or recommendations expressed in this publication are those of the authors and do not necessarily reflect the views of the USDA or NSF.
Development of this lesson was supported in part by the Cooperative State Research, Education, & Extension Service, U.S. Dept of Agriculture under Agreement Number 00-34416-10368 administered by Cornell University and the American Distance Education Consortium (ADEC). Any opinions, findings, conclusions or recommendations expressed in this publication are those of the authors and do not necessarily reflect the view of the U.S. Department of Agriculture.