Noxious Weed & Invasive Plant Control

Peninsula Environmental Group provides noxious weed control, invasive plant control and invasive plant mapping in a variety of environments.

We are a Washington State Department of Agriculture Commercial Pesticide Operator with five different licensed applicators on staff. We treat weeds in private residences, aquatic areas, ornamental landscapes, right-of-ways, industrial sites and utility corridors. We can treat invasive plants and noxious weeds in almost any environment.

Noxious Weeds and Invasive Plants

Noxious weed control is a vital aspect of ecological restoration. Noxious weeds cause a number of damaging and costly problems to homeowners, farmers, wildland managers, and foresters. Apart from being direct threats to the lives of humans, pets, and livestock, noxious weeds can cause irreparable damage to natural and wild areas. Species like reed canary grass (Phalaris arundinacea) and knotweed (Polygonum spp.) can physically choke out waterways and raise water temperatures and render areas uninhabitable by Washington’s salmon populations and other aquatic wildlife.

Noxious weeds are plants that have been introduced outside of their native range and are not controlled effectively by any natural predators or competition from native vegetation. Common noxious weeds include Himalayan blackberry (Rubus armeniacus), English Ivy (Hedera helix & H. hibernica), Scotch Broom (Cytisus scoparius) Japanese knotweed (Polygonum japonica), tansy ragwort (Senecio jacobaea), and poison hemlock (Conium maculatum). We use a variety of tools and machines to help us in our treatment and control of vegetation.

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How We Manage Noxious and Invasive Plants

Reinstallation of Native Flora

Simply removing the invasive plant doesn’t mean native plants will regrow into that space. Invasive plants grow faster and out-compete native flora easily. We treat the infested area then install native flora to help give native plants a much higher chance of survival and increase overall restoration success.

Ecologically Sound Techniques

We take pride in our ecological soundness. We always use the least toxic and least impactful approach to invasive plant treatments. We are licensed to treat in aquatic areas, and we use special chemical formulations that are non-toxic to salmon, amphibians and other wildlife in their applied concentrations.

Multiple Treatments

A single treatment of herbicide is rarely enough to treat these aggressive, exotic plants. Normal invasive plant control requires multiple treatments over 3+ years. Control techniques could change throughout the year, from manual removal, to broadcast herbicide, to spot applications.

Longterm Preservation

Invasive plants don’t often affect landscapes on the short-term. Thinking long-term: neglected landscapes can become inundated with unmanaged weeds resulting in serious consequences. Long-term preservation and control starts now.

Types of Noxious Weeds

Washington State designates three types of noxious weeds: Class A, Class B, and Class C.

Class A weeds are species that are limited in geographical distribution and have been deemed especially hazardous or costly. Class A species include giant hogweed (Heracleum mantegazzianum) and kudzu vine (Pueraria montana). Control of Class A weeds is mandated by law.

Class B noxious weeds are plants that are more widespread but still potentially damaging to natural and cultural resources. Their control is mandated at the local level. Class B species include scotch broom (Cytisus scoparius) and yellow archangel (Lamiastrum galeobdolon).

Class C species are widespread but can still be considered a nuisance. Their control is optional.

Common Invasive Plants

English Ivy: 

The density and abundance of English Ivy on the ground prevents other plants and trees from growing up and out of the ivy.

Our team has identified English Ivy as a primary cause for forest decline and reduced forest regeneration in Port Angeles, Port Townsend, Olympia and Poulsbo. English Ivy poses long-term threats to steep slope stability, soil loss, erosion, and forest regeneration. We treat English Ivy in the winter when nearby plants are dormant in order to reduce herbicide damage. We use a combination of both mechanical removal, either by hand or by machine, and a special chemical herbicide formula which can break through vines and thick waxy leaves.

English Ivy is most detrimental on shorelines, steep slopes, riparian slopes, and hillsides.

Scotch Broom: 

Scotch broom, a woody-yellow ornamental flowering plant, displaces native vegetation, reduces wildlife food and habitat, and interferes with reforestation by outcompeting tree seedlings for nutrients.

This plant is mildly toxic to pets and livestock, its fragrance can trigger allergic reactions in some people, and it is a highly flammable fire hazard.  Seeds in scotch broom can survive for nearly 80 years and persist through both fire and flooding.

Our team controls scotch broom using multiple methods: we cut and extract, topically treat foliage with herbicide, and use tractor tillers.

Himalayan Blackberry: 

Himalayan blackberry produces juicy, plump fruit. When managed and controlled in a small backyard garden, or in a park, the plant is a great food source for humans and birds alike.

However, this plant has a fruiting timeline limited to only a few months out of the year. Birds and other local wildlife populations need a diverse and reliable palette of plants to choose from as a source of food throughout the whole year.  But Himalayan blackberry’s aggressive growth pattern can overtake a native forest or riparian understory in a matter of years, resulting in the disruption and reduction of other important food sources.

Blackberry also rapidly grows along trees near streams and rivers, causing those trees to eventually die from lack of water, nutrients, and sunlight. This invasion results in streams and rivers lacking sufficient natural tree cover to shade from direct sunlight, which then increases water temperatures. With increased water temperatures, juvenile salmon and other local fish species are less able to survive.  Uncontrolled growth of Himalayan blackberry ultimately contributes to the problem of decreasing salmon populations in Washington State.

Organic Weed Control

For those clients who are sensitive, or for sensitive environments, we offer general organic weed control. We do not use chemicals like salt, vinegar, and oils, which have more chance of building up in soils and harming desired vegetation, and drastically alter soil pH levels. Instead, our organic weed control is old-fashion: hands, screw drivers and weed wrenches. This control method is especially important for weeds like field bindweed (also known as morning glory, Convolvulus arvensis) that bind themselves to other desirable plants.

We recommend 3-5 years of subscription based weed control services after all our environmental restoration and rehabilitation projects. This weed control and be herbicidal based, or organic depending on the client, the target weeds, and the environment.

We offer subscription based weeding services, at reasonable rates, which you can modify at any time to keep up with your garden and landscape bed weeds. In additional to organic weed control, our gardening services include mulching, pruning and hedging, landscape irrigation and general upkeep.

Pelargonic Acid

Pelargonic acid is a chemical substance that is found is almost all species of animals and plants. It is used as a “burn down” herbicide to prevent growth of weeds indoors and outdoors. Pelargonic acid is similar to vinegar; it is a skin and eye irritant but have no reactivity to soil, water, bark, or roots. The acid only affects green, chlorophyll filled leaves and needles.

Given it’s organic contents, and non-reactivity with anything but green leaves, the chemical is often used in organic horticulture and orchards to manage plants. We use pelargonic acid to control undesirable weeds in landscape beds, orchards, vegetable gardens, and other sensitive areas.

Case study – City of Olympia

In 2012, principal John Bornsworth, performed a series of forest landscape surveys in Priest Point Park in Olympia. These surveys represented all 300 acres of the park and their forest maturation, forest species present and native regrowth. After analysis of the data returned, it was apparent the areas of the Park infested with a thick ground cover of English Ivy were experiencing no coniferous or deciduous tree regrowth. The invasive Ivy practically arrested natural forest succession. In 20-50 years if left unmanaged, the current trees would begin dying and there would be no younger trees taking their place. In 100 years the 300 acre forest could have had very few naturally grown trees. Using this data, the Park launched a program to drastically reduce the presence of English Ivy.

Washington State Weed Control Board

For more information, or to see a complete list of exotic plants deemed noxious weeds in the Washington, please visit the Washington State Noxious Weed Control Board’s website at http://www.nwcb.wa.gov/.