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.