INVASIVE PLANTS AND WEEDS

Why Care?The spread of noxious weeds:

• Signal the decline of entire ecological watersheds.

• Severely impact the biodiversity and beauty of natural areas and cause widespread economic losses.

• Problem for urban as well as rural areas, and for private, state, and federal lands.

• Noxious weed species spare no segment of society—rancher, farmer, fisher, and cycler alike.

• Can’t leave well enough alone - when unmanaged, they spread rapidly, unceasingly, and silently.

Exotic Invasive Species – more than just plants

• plants• animals• microbes (fungi, bacteria, etc.)• viruses (i.e., diseases)

Plant Terminology• Native• ?

• Introduced• ?

• Invasive• ?

• Weed• ?

Native or Indigenous

• Originated where they now occur without the help of humans.• For example, native to North America• Well adapted to the local climate, soils, animals, and microbes.• How long have they been here?

Western Yarrow - Native plant widely distributed throughout North America

Introduced, Exotic or Non-native

http://www.youtube.com/watch?feature=player_profilepage&v=eDji4I1v4-E#!

Introduced, Exotic or Non-native

• An organism occurring outside of its natural home range• Other names include alien, foreign, non-indigenous• Introduced by humans

Alien Plants –Mississippi Valley Example

http://www.youtube.com/watch?v=Brb3ES5aOcY&feature=related

Introduced, Exotic or Non-native• Humans introduced non-native plants as:• Grains and food crops• Seeds in ship ballasts• Ornamentals• Plants for erosion control• Plants with higher forage value• Accidental

• Introductions of exotics continues today

Invasive Species• An organism that spreads and establishes over large areas and persists• Growth characteristics that allow it to dominate the ecosystem

Invasive Species Website = http://www.invasivespeciesinfo.gov/

Invasive Species•Often non-native (or alien) to the ecosystem• Not all non-natives are invasive

•Whose introduction causes or is likely to cause economic or environmental harm or harm to human health.

Cheatgrass

Juniper

Characteristics of Invasive Plants• Abundant seed producers• Rapid population establishment• Long-term survival of seeds• Occupy disturbed sites• Competitive• Lack of natural enemies

Cheatgrass

Juniper

Weed • Plant of little value or a plant “out of place”• Competes with crops and native species• Troublesome pest that affects the health an productivity of native landscapes

• “a plant whose virtues have not yet been discovered”...Ralph Waldo Emerson

• “plants that interfere with the growth of desirable plants and that are unusually persistent and pernicious. They negatively impact human activities and as such are undesirable” - Ross & Lembi – Applied Weed Science. 1999

Impacts of Weeds• Reducing biological diversity

• Altering hydrologic conditions

• Altering soil characteristics

• Altering fire intensity and frequency

• Interfering with natural succession

• Competing for native pollinators

• Replacing complex communities with monocultures

• Displacing rare plant species

• Noxious = plant species that have been designated “noxious” by law. • The word “noxious” simply means deleterious• Weeds are declared noxious by states or counties.

• In Idaho, hundreds of weed species exist. However, only 36 are designated noxious by Idaho law.

Noxious Weeds

Idaho Noxious Weed Guide: http://digital.lib.uidaho.edu/cdm/compoundobject/collection/ui_ep/id/1294/rec/1

Plant Terminology•Native• Originated where they now occur without the help of humans

• Introduced• Introduced by humans, exotic or not native

• Invasive• Growth characteristics that allow it to spread and dominate the ecosystem

•Weed• Troublesome pest that affects the health an productivity of native landscapes• Noxious Weeds = designated “noxious” by law

Weed Control Approaches• Chemical

• Mechanical

• Biological

• Cultural

Weed Control Approaches• Chemical – herbicides to reduce or prevent weeds

• Mechanical

• Biological

• Cultural

Weed Control Approaches• Chemical – herbicides to reduce or prevent weeds

• Mechanical – removal or damage to weeds with physical/mechanical forces

• Biological

• Cultural

Weed Control Approaches• Chemical – herbicides to reduce or prevent weeds

• Mechanical – removal or damage to weeds with physical/mechanical forces

• Biological – suppress weeds with living organisms including parasites or pathogens

• Cultural

Weed Control Approaches

• Chemical – herbicides to reduce or prevent weeds

• Mechanical – removal or damage to weeds with physical/mechanical forces

• Biological – suppress weeds with living organisms including parasites or pathogens

• Cultural – alter agricultural practices (fertilize, cultivate, graze) to suppress weeds

Weed Control Approaches• Chemical – herbicides to reduce or prevent weeds

• Mechanical – removal or damage to weeds with physical/mechanical forces

• Biological – suppress weeds with living organisms including parasites or pathogens

• Cultural – alter agricultural practices (fertilize, cultivate, graze) to suppress weeds