The following is reprinted from my recent article in the Tillamook County Headlight Herald.
Looking across a pasture, lawn or garden, any farmer or gardener can you tell you about weeds. Weeds are unwanted plants, generally because they grow in places we don’t want them to occupy. But often, these plants can be a much graver threat to our human and naturally-managed landscapes. Instead of just weeds, we refer to them as invasive plants. Examples include Himalayan blackberry, knotweed, cheat grass, and English ivy.
Invasive plants are those that are so successful that they grow to the exclusion of most or even all others. It’s not just plants that can become invasive; some species of animals have become invasive on virtually all continents. Some famous examples include rabbits in Australia, Norway rats, gypsy moths and Africanized honeybees in the United States, and the mongoose in the South Pacific islands. Another famous example is the pairing of the non-native Asian tiger mosquito with the West Nile virus in North America.
Invasive species of plants and animals overcome geographic barriers—often by hitchhiking with humans, cargo, or domesticated animals—into new habitats. In these new habitats, they have few or none of their natural enemies and quickly take over.
The invasion of unwanted plants and animals into new habitats is one of the most important challenges of our times. Invasive species cost Americans alone an estimated $138 billion a year in control, prevention and direct economic losses. Next to the immediate loss of habitat, invasive species are the second largest threat to native plants and wildlife world wide.
Gardening to Eliminate Invaders
Gardens and gardeners are one of the most important pathways for invasive plants to move into new places. You can help stop the biological invasion by eliminating known invasive plants from your garden, preventing the introduction of new, aggressive plants, and replacing non-native invaders with friendly native plants.
Some common plants to avoid include: English or Irish ivies (Hedera helix or H. hibernica), butterfly bush (Buddleia davidii), knotweed (Fallopia spp.), bachelor’s buttons (Centaurea cyanus), purple loosestrife (Lythrum salicaria), money plant (Lunaria annua), spreading bamboos, yellow flag iris (Iris pseudocorus), chameleon plant (Houttuynia cordata), French, Scotch, Spanish, or Portugese brooms, English holly (Ilex aquifolium), spurge laurel (Daphne laureola) , Jubata grass (Cortaderia jubata), leafy or myrtle spurge (Euphorbia esula or E. myrsinites) , and old man’s beard (Clematis vitalba). You can find some excellent replacements for these plants by picking up a copy of a new booklet titled, “GardenSmart Oregon: A Guide to Non-Invasive Plants” at the OSU Extension Service office or by going to www.oregoninvasiveshotline.org for an on-line version. Thanks to support from many corporate and public sponsors, the guide is free.
Volunteering to Map the Invasion
One of the key issues with invasive species is that once they get started in a new location, it can be difficult if not impossible to completely remove them. One of my colleagues at Oregon State University likes to say, “If you don’t catch them early, biological invasions are forever!” Like a wildfire, invasive species start out as small patches of a few organisms, and then when conditions are right, spread rapidly across the landscape. So it is important to identify and locate the invaders before they get a toe-hold. Once they are established, it is best to know the direction and spread of the invasion.
That is why the Tillamook Estuaries Partnership, Oregon Sea Grant Extension and The Nature Conservancy are piloting a new program to train citizens to spot invasive plants and animals before they get out of control, as well as to map the extent of invasions already underway. The Tillamook Invasive Species Early Detection Program will be a model for others across Oregon.
Thirty local volunteers will be trained to identify and map invasive species on publicly-managed lands in Tillamook County. The all-day, intensive training will take place on August 1st from 9:30 AM to 3:30 PM at the Oregon Department of Forestry, Tillamook District office conference room (5005 3rd Street, Tillamook) and at a selected field site. Participants will learn about biological invasions, learn to identify some important examples, and spend some time in the field looking for them. The training is free. To register, please call Pat Penney at the OSU Extension Service; (503) 842-3433.
To warm up for the training, the Tillamook Estuaries Partnership will sponsor a free presentation on aquatic invasive species by Oregon Sea Grant’s Dr. Samuel Chan. This open-to-the-public event will take place at the Oregon Department of Forestry, Tillamook District office conference room on Wednesday, July 30th, from 6:00-8:00 PM. For more information, contact TEP; (503) 322-2222.