RS 478: Lecture 16 Weed Control and Regulations in Restoration
4. Restoration Regulations
5. Industry Regulations
• 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
• 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
• 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
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,
• Any approaches unacceptable for a particular site? Social, economic, cultural
• 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
• 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
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.