RS 478 Lecture 16: Weed Control and Restoration Regulation
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Department
Rangeland Ecosystem Science
Course
RS 478
Professor
Mark Paschke
Semester
Spring

Description
RS 478: Lecture 16 Weed Control and Regulations in Restoration Outline 1. Introduction 2. Approaches 3. Considerations 4. Restoration Regulations 5. Industry Regulations 1. Introduction • What is a weed? o Typical characteristics of weeds: Annuals or short-lived perennials, Adapted to high nutrient soils, Fast growth and high seed production • When is weed control needed? o Presence of weeds at the site is a reason for restoration; Disturbance/restoration creates opportunity for weed establishment Review Question: What is a weed? ü Any plant growing where it is not desired 2. Approaches • Avoidance: • Don’t introduce weeds to your site via: Mulch, Topsoil, Restoration seed mix, Containerized stock, Livestock • Survey your site and surrounding areas for weeds • Check the soil seedbank at the restoration site • Chemical: Application of chemicals that are toxic to undesirable species. o Chemical selectivity, Broadleaf herbicides, Others (grass specific, cool- season specific, etc.), o Application timing: When weeds are vulnerable but desired species are not or immediately after seeding desirable species o Application placement: Depth in soil, Spot spraying, Cut stump spraying o Special consideration for chemical control in restoration: Non-target effects/drift Other plants, Native genotypes (good competitors with weeds,) Other trophic groups, Regulations, Public perceptions, What replaces the weeds • Physical: Hand pulling or hoeing, Fire, Grazing, Mowing, Chaining or masticating, Flooding, Mulch, Solarization • Cultural: Competition Cover crops, Successional management o Native weeds can be important in plant community development after disturbance • Biological Control: o Enemy Release Hypothesis of Darwin (1859) & Elton (1958): Invaders are successful because they have left their natural enemies behind o Introduction of natural enemies from the weed’s native range. o Once released, biocontrols are inexpensive Can be effective at reducing weed abundance Review Question: What is biological control of weeds? ü A form of control which introduces natural enemies/predators from the weeds native range to reduce/suppress the population Review Question: What is meant by using avoidance as a technique for weed control? ü Avoiding introducing weeds to a site through contaminated seed mixes, mulches, topsoil, etc. 3. Considerations • Any approaches unacceptable for a particular site? Social, economic, cultural considerations? • Were weeds present prior to disturbance/restoration? Are they likely to have large seed bank? viable rhizomes? • What is the spatial extent of weeds at the site? • What is the biology of the weeds? Life cycle? • Have they changed the soil/site? • Budget considerations? Tradeoffs between upfront costs vs long-term control? • Combination of approaches and/or repeated treatment may be needed (Example: cheatgrass) 4. Regulations • Prescriptive vs. outcome based: o Prescriptive – these are the methods you must use. o Outcome based – these are the conditions you must achieve. Review Question: Describe the difference between prescriptive and outcome-based regulations? ü Prescriptive regulations are methods you must use to get to a desired outcome. Outcome based are conditions are must achieve. These lead to defined results without specific direction regarding how those results are to be obtained. Fo
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