Purple Loosestrife Alert!

What is Purple Loosestrife?

Lythrum salicaria is an introduced, hard, aggressive perennial that occurs predominately in wetland habitats. Originally from Europe, it was inadvertently introduced to the U.S. in the 1800's in ship ballast water and intentionally as a medicinal herb. It can now be found in 40 of the lower 48 states and Canada.

Description:

• 2-7 feet tall
• Flowers on spike, attached closely to stem
• 5-6 petals per flower
• Opposite leaf arrangement
• Stiff, four-sided stem
• Blooms July-early Sept.
• A single mature plant can produce up to 2.5 million seeds per year.

Why is Purple Loosestrife a Threat?

Wetlands are the most biologically diverse and productive components of our ecosystems in Maryland. Productive wetlands are the backbone support for a healthy Chesapeake Bay. Hundreds of species of plants, birds, mammals, reptiles, insects, fish, and amphibians rely on healthy wetland habitat for their survival.

Once this plant becomes established, it rapidly degrades wetland habitat by out-competing beneficial native vegetation. If left unchecked, purple loosestrife forms vast monotypic stands that will dominate an area and provide very little if any habitat for wildlife.

An estimated 190,000 hectares of wetlands, marshes, pastures, and riparian meadows are affected in North America each year. This has an economic impact of millions of dollars. Purple loosestrife is classified as a noxious weed in 19 states; however, it is not considered so in Maryland at this time.

What you can do to help!

Because purple loosestrife is so widespread in the U.S., its total eradication is unlikely. However, the spread of purple loosestrife can be halted and newly invaded areas can be controlled.

Prevention is the best way to stop the purple loosestrife invasion.

• Don't plant purple loosestrife in your garden! Even Lythrum varieties advertised not to make seeds can cross-breed with the invading loosestrife to make seeds.
• Be on the look out for pioneering plants or isolated small colonies. Notify the proper authorities. If they occur on your own property, remove the plants or cut off the flower heads, bag and destroy them. Repeat throughout the flowering season mid-June, July - early August before seeds are set.
• Rinse equipment, gear, or clothing and footwear used in infested areas before moving to un-infested areas.

Control Methods

Any control method you select should be repeated for several years to catch missed plants and those established from seed. Purple loosestrife seeds remain alive in the soil for many years.

By Hand (for small clusters)

Pull young plants, bag and destroy all materials. Dig older plants and remove all the roots. Any remaining will sprout new shoots. Be careful to avoid excessive soil disturbance. If this is unavoidable, consider chemical methods.

By Herbicide (on larger populations)

As with any herbicide, extreme care must be taken to ensure the control of loosestrife and minimize damage to desirable vegetation. It is best to call the Cooperative Extension for up-to-date information on the herbicides recommended for loosestrife control and all precautions that need to followed when using herbicides.

Biological Control (in the future)

Refers to the use of natural "enemies" or agents such as parasites, predators, or pathogens to control plant populations. In the past ten years, much research has been conducted to find selected insects that feed specifically on purple loosestrife as a means to naturally control the spread of the plant. Back in the 1800's when purple loosestrife was introduced to this country, left behind in Europe were the natural insect enemies of the plant that helped to prevent population explosions. The goal of biological control is to reduce numbers of the target plant to lessen its ability to displace native vegetation. It does not eradicate a plant population. Obviously, extreme caution must be taken when introducing one organism to control another. Prior to introduction of a biological control agent, intensive testing is conducted to ensure that a safe and effective agent is selected. Currently, the effectiveness of this option are being field tested. As of 1996, biological controls have been released in 25 states and seven Canadian provinces.

Alternative Plantings for Purple Loosestrife

If you currently have purple loosestrife or a cultivar growing in your garden, it could contribute to the loss of fish and wildlife habitat. Please remove it (roots and all) or at least cut off the flower tops before they begin to form seed. Dispose of all materials properly.

Several species of garden perennials display characteristics similar to purple loosestrife, yet they pose no threat to our natural environment. The following are examples of some alternatives to purple loosestrife.

• Blazing Star or Gay Feather (Liatris spp.)
• Delphinium (Delphinium spp.)
• False Spirea (Astilbe arendsii)
• Foxglove (Digitalis purpurea)
• Lupine (Lupinus)
• Lobelia (Lobelia cardinalis)
• Obedient Plant (Physostegia virginiana)
• Salvia (Salvia superba)
• Siberian Iris (Iris)
• Spike Speedwell (Veronica spicata)

Environmental Education Series

The goal of the Department of Recreation and Parks is to preserve a balance of ecological, natural and environmental values in Open Space land throughout the County. We strive to manage these areas in a way that will preserve their ecological integrity while making them available to the public for passive recreational use.

A key element in our management plan is public awareness and education. This brochure is one of a series of publications designed to educate the public on matters related to the conservation and preservation of our environment.

To help accomplish this goal, our staff is available to speak with various civic and community organizations and to assist with the planning and implementation of projects such as habitat enhancement, reforestation, stream walks, water quality monitoring, etc. It is our firm belief that only by working together can we fulfill the moral and civic responsibility with which we have all been charged . . . the stewardship of the land.

For additional information, or to become involved in our program, please call 410-313-4700, or email the Department of Recreation and Parks.

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