BACKYARDS ON THE BAY  A yard care guide for the coastal homeowner

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Appendix 3: Invasive Plant List And Control Strategies

Exotic invasive plants are not native to this region and can outcompete native plants. Generally these invasive plants grow quickly and are spread by animals that eat their fruits or seeds. Some of these invasive plants are still sold in nurseries. Invasive plants thrive in disturbed areas such as along roads and new developments.

The following is a list of common invasive plants in Rhode Island coastal areas with a description of control techniques.

  • REMINDER: The easiest time to control invasive species is when they are not dominant in the landscape. Clear-cutting invasive species in a buffer or coastal wetland is NOT recommended. Invasive species in this setting do provide some erosion and sediment control benefits. Always consult a professional to develop a restoration plan for the removal of invasive species in these sensitive areas.
  • Never purchase or plant the species listed in Section Four as Invasive Plants.

Invasive Plants:

Common/Scientific Name

Description

Control Techniques

Autumn Olive

Elaegnus umbellata

Fast-growing woody shrub that thrives in disturbed areas in full sun; drought tolerant; intolerant of shade; leaves are dark green above and silvery below; produces large amounts of fruit which is silvery in color and turns red as it matures.

Cutting: cut trees at ground level before they have set seed; cutting needs to reoccur due to resprouting.

Hand pulling is effective for young seedlings; plants should be pulled as soon as they are large enough to grasp and before they produce seeds; hand pull seedlings after rain when soil is loose.

Bush Honeysuckle

Lonicera morrowoii

A flowering shrub with a fragrant white to yellow flower; berries are dark red and may remain on shrub through the winter; tolerant of a variety of conditions; invades disturbed sites and woodland edges.

Hand pulling: young plants can be hand-pulled.

Grubbing: use a digging tool to remove the entire plant including the root; any part of the root not removed may resprout.

Japanese Knotweed

Polygonum cuspidatum

Bamboo-like plant growing five to ten feet tall with small flowers in the fall; spreads quickly to form a dense stand; spreads rapidly from long rhizomes and by seed; can tolerate a variety of conditions including full shade, high temperature, drought and high salinity; poses a threat to river and stream banks where it can survive severe floods.

Plants can be removed with a grubbing hoe; remove entire plant including roots and runners; juvenile plants can be pulled if soil is moist.

Multiflora Rose

Rosa multiflora

Thorny shrub with white flowers and small red rose hips; found in fields and roadsides; forms dense thicket which can choke out native plants; adapted to wide range of environments from extremely dry to standing water.

Plants can be removed (removing the entire root) with a shovel or grubbing hoe; for areas highly infested mowing or cutting three to five times a year for two to four years.

Oriental Bittersweet

Celastrus orbiculata

Oriental Bittersweet is a deciduous woody vine that can reach 60 feet high depending on surrounding vegetation; fruit is green changing to bright yellow/orange once mature and is used in floral decorations; the vines damage and kill native vegetation by constricting and shading the trees or shrubs; prevalent along road sides, field edges, thickets; shade tolerant; seeds remain viable for several years and control actions must continue until seed sources are eliminated.

Cutting: cut vines as close to the root as possible; cutting should continue from spring until early autumn on a regular basis to prevent resprouting.

Hand pulling: young roots can be hand pulled; any portion of the root not removed can resprout.

Purple Loosestrife

Lythrum salicaria

Outcompetes wetland vegetation, thrive in moist soil and full sun; has a showy purple flower which blooms in mid summer.

Do not cut or mow since it will increase the spread of plants; Hand pulling can be effective for plants less than two years old; Biological control: URI is conducting a study of the effectiveness of biological control on loosestrife at the Roger Williams Zoo.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Some other invasive plants to avoid:
  • Amur Privet, Ligustrum amurense
  • Barberry, Berberis vulgaris
  • Canada Thistle, Cirsium arvense
  • Common Buckthorn, Rhamnus cathartica
  • Crown Vetch, Coronilla varia
  • Japanese Honeysuckle, Lonicera japonica
  • Norway Maple, Acer platanoides
  • Porcelain Berry, Ampelopsis brevipedunculata
  • Russian Olive, Elaeagnus angustifolia
  • Saltspray Rose, Rosa rugosa
  • Spiderwort, Tradescantia virginiana
  • Tree-of-Heaven, Ailanthus altissima
  • White Mulberry, Morus alba
  • Burning Bush, Euonymous alatus
  • Wisteria, Wisteria floribunda

Phragmites australis

Phragmites is a tall reed grass that grows up to 15 feet high and is native to this area. Phragmites can grow in both fresh and brackish water marshes and can be found growing in narrow bands along the upper edge of salt marshes. Phragmites growing along the upland edge of a salt marsh can provide important benefits such as acting as a buffer between the marsh and the upland and as a filter of runoff from the upland. Even though Phragmites is native to this area, it can become invasive under certain conditions. Salt marshes disturbed by human activities such as filling and the construction of roads that restrict tidal flow can become dominated by Phragmites. Phragmites also tolerates waters that are degraded and high in nutrients. In these disturbed or degraded areas, Phragmites may outcompete other marsh grasses, reducing wildlife habitat value, plant diversity and abundance. It is believed that these invasive Phragmites stands are a non-native strain of Phragmites introduced from Europe. Extensive stands of Phragmites can pose a fire hazard to nearby homeowners because when the plants die back they leave an abundance of dead plant material that can catch fire in dry conditions.

How to prevent the spread of Phragmites:

Since Phragmites can thrive near freshwater inputs, in nutrient-rich waters and in areas of sedimentation, limiting watering, fertilizing and preventing erosion can be a strategy in controlling its spread. Creating a buffer of native vegetation can filter out nutrients and sediments entering the marsh. Preventing erosion of the shoreline and slowing down runoff from paved surfaces will reduce the amount of sediment reaching the salt marsh. Cutting has not been proven to be effective at controlling Phragmites and in fact, cutting may actually spur the re-growth and vigor of Phragmites.

Areas seriously impacted by invasive Phragmites can be successfully targeted for restoration measures. Evaluating whether a Phragmites stand should be restored depends upon the severity of the problem, the landscape setting, the disturbance history and the likelihood of success.


 

 

| TABLE OF CONTENTS | INTRODUCTION | SECTION 1 | SECTION 2 | SECTION 3 | SECTION 4 | SECTION 5 | SECTION 6 |
SECTION 7 | APPENDIX 1 | APPENDIX 2 | APPENDIX 3 | APPENDIX 4 | APPENDIX 5 | APPENDIX 6 | APPENDIX 7 |