Robert Emanuel, Ph.D.Water Resources and Community Development Faculty,
Tillamook and Clatsop counties
Introduction
What are invasive species?Why should we care?Biology & managementSome common invadersWhat can gardeners do about them?Resources for more information.
Invasive species means an alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health.
Biological invaders destroy habitats or out‐compete native plants and
animals.
At least 30 new potential biological invaders enter the US every day…
Invasive species costs Americans about $143 billion/year!
Why should we care?
Understanding Biological Invasions
“Invasive”
Definitions: Invasive PlantsExotics
(non‐native)Lots of beneficial species: Crops, pasture, forestry & ornamentals.
“Noxious”A regulatory designation.
“Weed”A plant growing where you do not want it.
Spreads outside of cultivation, and causes human, environmental, economic harm.
NativesCo‐evolution with other species, our natural heritage
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Weedy terms are used interchangeably, resulting in this problem. Euler diagrams
What makes a plant invasive?
Lack normal environmental constraintsFast growth and reproductionHighly adaptable a wide range of conditionsOften can transform their environmentPromoted by new or existing disturbancesLess biodiversity in the native ecosystemSometimes work with other invasive species
We also have learned from hard experience that options are very limited and costly when invasives become established in large populations.
Himalayan Knotweed: Polygonum polystachyum
Photo ‐ knotweed
Knotweed: Fallopia x bohemicum
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3) Bohemian knotweed is a hybrid of Japanese knotweed (Polygonum cuspidatum) and giant knotweed (Polygonum sachalinense). Photo: Sasha Shaw
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A big root!
knotzillaweed?
Photo ‐ English ivy
English Ivy: Hedera helix
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2) English ivy (Hedera helix) Photo: Susan Aldrich-Markham
Photos – black walnut tree covered by English ivy
English Ivy
2002
2006
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Ivy weakens a tree by competing for water, nutrients and sunlight. The added weight of the vines makes the tree more likely to fall down, especially during winter storms. This black walnut tree covered with ivy only has a few leaves left at the top because it has been so stressed by competition from the ever-increasing mass. Wouldn’t a healthy mature black walnut tree be more attractive in the yard than this? Photos: Susan Aldrich-Markham
Policeman’s Helmet: Impatiens gladulifera
Garlic Mustard, Alliaria petiolata
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Garlic mustard can be found year-round in forest understory, forest edges, shaded roadside, urban areas, riparian areas, floodplains, and on agricultural lands.
Parrot feather, Myriophyllum aquaticum
Yellow Flag Iris: Iris pseudacorusPhoto: OSU
Old Man’s Beard: Clematis vitalba
Photo: Wikim
edia
Old Man’s Beard: Clematis vitalba
Shining Geranium, Geranium lucidum
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Shining geranium is an annual that bears a tiny pink to purple flower and a long, straight, pointed beak that appears at the top of the fruit pod (hence its nickname shining crane’s bill). Its round and obtusely lobes leaves are shiny with widely scattered hairs. Towards the end of the summer, the leaves turn red and develop a waxy sheen. This pretty, yet noxious weed is native to Europe, Asia, and North Africa, and has a history of medicinal uses. It was first introduced to the United States for ornamental purposes; thus it likely escaped from gardens into wildlands. Shining geranium reproduces by seed and germinates in the late winter. It is spreading rapidly into oak and riparian habitats in Oregon’s Willamette Valley. It has become widespread in the Howard Buford Recreation Area near Eugene, and is also present in the Rogue River basin. Shade-tolerant, shining geranium invades undisturbed forest understories and forms monoculture patches that replace native plant communities. Dense blankets of shining geranium cover small, mossy boulders and can extend up bases of tree trunks (Newhouse, pers. comm., March 29th 2007). Control methods for G. lucidum include (1) hand-weeding for isolated plants or small populations, (2) burning with a propane-based flaming unit is effective if done several times each growing season, and (3) chemical control with a 1.5 – 2% solution of either a broadleaf selective herbicide, such as triclopyr, or a non-selective herbicide, such as glyphosate. (Christer LaBrecque, pers. comm.. April 2007) LOOK FOR Tiny pink to purple flower Long, pointed beak at the top of the fruit pod Shiny, round, obtusely lobed leaves that turn red toward the end of summer. Red stems WHEN It is most easily identified during flowering, which occurs from spring until late July. WHERE It tends to grow in monotypic stands in shady areas, especially oak woodlands. WHAT TO DO Only pull this plant if you are confident in its identification and the populations is isolated and small. Probably tracked by deer. Can grow in carpets 1.5 ft deep.
Lynn Ketchum, OSU EESC
Herb Robert: Geranium robertianum
Photo: University of G
eorgia
Spurge Laurel: Daphne laureola
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LOOK FOR: Leaves alternate and spirally arranged and cluster at the shoot tips. Leaves dark green and shiny on top and lighter on the underside. yellow-green, bell-shaped flowers that emit a honey-like fragrance. Green unripe and black ripe berries. WHEN It is found year-round, blooming March - May. WHERE It can be found along roadsides and in open, moist woods in the lowlands. WHAT TO DO Please report but do not try to pull this plant. Spurge laurel is an evergreen shrub that grows from 0.5 to 1.5 meters and can grow upright or arched at the base and spread upward. Young branches are green while mature branches are grey with a yellow hue. The leaves are alternate and spirally arranged, and are dark green and shiny on top and lighter on the leaf underside. The leaves cluster at the shoot tips. The yellow-green, bell-shaped flowers bloom between March and May and emit a honey-like fragrance. The fruits are berries that are green at first and then blacken when ripened This European native has become a growing problem in the Pacific Northwest. It has been documented in Washington and Oregon and is creeping into coastal British Columbia.��Spurge laurel reproduces by seed and vegetatively through the production of root sprouts. Seeds are primarily dispersed by birds and rodents.��Spurge laurel poses a particular threat to Douglas fir forests and Garry Oak woodlands of the Pacific Northwest. The shrub can form thick patches that block out sunlight, out-compete native flora for water and nutrients, alter the soil chemistry, and potentially alter natural succession. The leaves, bark, and berries of the plant are also toxic to humans, dogs, and cats. Studies show that the most effective way of eliminating spurge laurel is with herbicidal treatment; manual methods have produced some successful results, but precaution must be taken when using such methods because of the plants toxins.
Photo ‐ butterfly bush infestation in Lane Co.
Butterfly Bush (Buddleia davidii) Photo: OSU
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This butterfly bush infestation is along the Salmon River in Lane County. Butterfly bush produces abundant seeds that are easily spread by water, and it thrives on sites with regular disturbance. It grows well in infertile soils; it tolerates summer drought and winter flooding. Photo: Brad Withrow-Robinson
Photo – butterfly bush infestation in Lane Co.
Butterfly Bush: Buddleja davidii
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Butterfly bush flowers provide nectar for adult butterflies, as do many other flowers as well. The food necessary for a butterfly’s larvae, however, is usually only one species or a few related plant species. Some native butterfly species depend on willows for their larval food, one of the plants crowded out of its streamside habitat by butterfly bush. Photo: Brad Withrow-Robinson
Purple Loosestrife: Lythrum salicaria
English Holly: Ilex aquifolium
Lynn Ketchum, OSU EESCCommon Gorse: Ulex europaeus
French Broom: Genista monspessulana
Portuguese Broom: Cytisus striatus
Jubata Grass: Cortaderia jubata
Fennel: Foeniculum vulgare
But wait! There’s MORE!
Cotoneaster: Cotoneaster spp.
Petasites japonica var. giganteum Photo: Kurt W. Heckeroth
Know the enemy & teach others about themGrow native & non‐invasive wherever possibleHelp others to do the sameHelp the public with information on treatmentMonitor and report new invadersCheck clothes, vehicles, pets when out & about
What can gardeners do?
Don’t share unless you know it’s not invasiveCheck seed mixes before you buy themStay away from generic wildflower mixturesWatch for hitchhikers in nursery stockUse weed‐free soil and mulchWatch introductions for aggressive behaviorDon’t dump your yard clippings in the wild!
If you have a known invasive (but can’t part with it)
Deadhead faithfullyUse root barriersDispose of plant material properly—bagged in the garbage or burned (completely)Please don’t share your invader with others!
Contain it, control it, or cage it!
For Water Gardeners
Always wash new introductions (think snails)Keep water garden separate from native watersNever dump water garden materials or water into native watersResearch your plants for invasive potential—many commonly used aquatics are!
Some Resources
http://plants.usda.gov/java/noxiousDriver
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One resource for
www.plantright.org
Robert M. Emanuel, Ph.D.Water Resources & Community DevelopmentTillamook & Clatsop counties2204 Fourth StreetTillamook, OR 97141(503) 842‐5708 X 2 robert.emanuel@oregonstate.edublogs.oregonstate.edu/h2onc