Stop Oriental Bittersweet in MN

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Goodhue County Extension Master Gardener Genella Mussell
answering questions about invasive Oriental Bittersweet

by Genella Mussell, Goodhue County Extension Master Gardener

As leaves, trees and undergrowth begin to fill out and eventually paint our world green I want to remind folks to be on the lookout for invasive species. We have heard the awful news about the Emerald Ash Borer for our Ash trees. How many of us as gardeners are aware of Oriental Bittersweet?

Bittersweet? That beautiful berry and vine used to make those fall wreaths often seen at craft fairs and stores? Well, yes and no. The bittersweet that should be used in these wreaths is the American Bittersweet. Unfortunately there may be wreaths made with a variety named Oriental Bittersweet.

The bittersweet causing concern for the Minnesota DNR is the Oriental Bittersweet. Unfortunately it was introduced to the US as an ornamental vine. It is a climbing woody perennial vine. It has proven to be very aggressive. It can grow to heights of 66’. Because of this aggressive growth it can smother trees, shrubs and other vegetation. It had been known to cover entire trees and pull them down due to the heaviness of the growth. The vines can girdle and kill grown trees.

The Oriental Bittersweet looks very similar to the American. Differences that can be noted are in how the fruit and flowers grow and the color of the berries. The Oriental Bittersweet has fruit and flowers located in the leaf axils along the length of the stem. American bittersweet, however, only has fruit and flowers in terminal clusters. The berries of the American Bittersweet are orange and those of the Oriental yellow. These are best seen in the fall.

Why the warning? As stated, this vine is very aggressive. The Oriental Bittersweet has at present a limited distribution in Minnesota, which is why we need to stop it now.  As gardeners we should be on the lookout for it or at least aware of it. Because it is a favorite in ornamental wreaths it may be unintentionally introduced. So as a warning, when attending craft fairs or shows, take a careful look at the wreath and make sure they are not compromised of the Oriental Bittersweet.

Sadly, we have any number of invasive species of which we must be aware. If we take a moment to familiarize ourselves with the plants around us or those with which we may come in contact, we can perhaps slow the spread of some of these species. We should remember the old adage, “An ounce of prevention is worth a pound of cure”.

Online Resources:

Garlic Mustard Videos

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TOO MUCH SNOW TO GARDEN? WATCH THESE VIDEOS :

Perfect timing! An upside of our new snow – it buys us time to get the word out. We have just a few weeks until garlic mustard goes to seed in Goodhue and surrounding counties. It is important for us as  to take action with best practices in our own back yards and through education – watch the video to find out how.

Sorry about the first attempt to post this and the accompanying message that lead to nowhere – something glitched when trying to embed the  first video, but as a result I found a second.  Hence, just the links now. Your humble blogger, nlb

Flowers, They Aint Always Pretty

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What could be a pleasant spring hike could leave you very disappointed.  Garlic mustard (Alliaria petiolata) has been found within the Red Wing city limits in the last couple years.  If you also appreciate native wildflowers and wildlife, this is one invasive species that should be “nipped in the bud” before it becomes established.  Like most invasive species it is most efficient and cost-effective to eliminate small populations before they expand and become widespread.

The good news is that the garlic mustard populations  within Red Wing are small, and if addressed now might be controlled or contained.

Garlic mustard is easy to identify.  The herbaceous biennial stems are 12 – 36 inches tall and are the only plant with four white petals blooming in wooded areas and edges in May.  The leaves are round/scalloped and the stems smell like onion or garlic when crushed.  It is critical to pull and destroy the plants before they go to seed in early to late May as garlic mustard seeds remain are viable in the soil for 5-7 years.  Small patches can be pulled by hand (be sure to get the full root) burned or chemically treated.

Garlic mustard is a Minnesota Department of Agriculture Prohibited noxious weed.  It poses and ecological threat to high quality woodlands upland and floodplain forests, not just into disturbed areas.  Invaded sites undergo an ecological decline of native herbaceous cover within 10 years – often garlic mustard is the only plant that remains.   Garlic mustard alters habitat native insects and thereby birds and mammals.  Some studies in New England found that trees did not reproduce in areas taken over by garlic mustard.

According to the Minnesota DNR website “species on the Prohibited noxious weeds listed must be controlled, meaning efforts must be made to destroy all propagating parts and prevent seed maturation and dispersal, thereby reducing established populations and preventing reproduction and spread as required by Minnesota Statutes, Section 18.78. Additionally, transportation, propagation, or sale of these plants is prohibited.”

If you see garlic mustard in your woodland  address it now.  If not, next year you will be guaranteed even more.  For more information see http://www.dnr.state.mn.us/invasives/terrestrialplants/herbaceous/garlicmustard.html

Native Plant Alternatives

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A great reference of native plant alternatives to plants that can become invasive.  (Source: US Forest Service Celebrating Wildflowers Website: http://www.fs.fed.us/wildflowers/nativegardening/alternatives.shtml#note1)

 

Traditional  Planting

Desirable Characteristics

Great Alternatives

Japanese Wisteria showy flowers, fragrance woodland phlox, Phlox divaricatus
sweet azalea, Rhododendron canescens
coast azalea, Rhododendron atlanticum
American wisteria, Wisteria frutescens
Japanese Honeysuckle fragrant flowers leatherflower, Clematis viorna
Carolina jasmine, Gelsemium sempervirens
trumpet honeysuckle, Lonicera sempervirens
sweetbay magnolia, Magnolia virginiana
purple passionflower, Passiflora incarnata
English Ivy Drought Tolerant Evergreen plantain-leaved sedge, Carex plantaginea
marginal woodfern, Dryopteris marginalis
woodland aster, Eurybia divaricatus
alumroot, Heuchera villosa
creeping mint, Meehania cordata
Allegheny spurge, Pachysandra procumbens
creeping phlox, Phlox stolonifera
Solomon’s seal, Polygonatum biflorum
Christmas fern, Polystichum acrostichoides
Autumn Olive Drought Tolerant strawberry bush, Euonymus americanus
wax-myrtle, Myrica cerifera
meadowsweet, Spiraea latifolia
mapleleaf viburnum, Viburnum acerifolium
Barberry Cheap/Nice Fruit strawberry bush, Euonymus americanus
shrubby St. Johnswort, Hypericum prolificum
winterberry, Ilex verticillata
deerberry, Vaccinium stamineum
mapleleaf viburnum, Viburnum acerifolium
Purple Loosestrife Long Bloom Season/Wet Tolerant swamp milkweed, Asclepias incarnata
sweet pepperbush, Clethra alnifolia
purple coneflower, Echinacea purpurea
gayfeather, Liatris spicata
grass-leaved blazing star, Liatris pilosa
green-headed coneflower, Rudbeckia laciniata
New York ironweed, Vernonia novaboracensis
Miscanthus species Strong Vertical and Fall/Winter Interest split-beard bluestem, Andropogon ternarius
switchgrass, Panicum virgatum
sugarcane plumegrass, Saccharum giganteum
little bluestem, Schizachyrium scoparium
Indiangrass, Sorghastrum nutans
Lesser Celandine Early Color spring beauty, Claytonia virginica
yellow ragwort, Senecio aureus
Other spring ephemerals, if nursery propagated
Asian Bittersweet Showy Fruits American bittersweet, Celastrus scandens
Virginia rose, Rosa virginiana
Porcelainberry Fast Grower/Colorful Fruits gray dogwood, Cornus racemosa
Virginia creeper, Parthenocissus quinquefolia
swamp haw viburnum, Viburnum nudum
Shrubby honeysuckle Replant after removal spicebush, Lindera benzoin
highbush blueberry, Vaccinium corymbosum
arrow-wood viburnum, Viburnum dentatum
Burning Bush Euonymus Fall Color fringed bluestar, Amsonia ciliata
Hubricht’s bluestar, Amsonia hubrichtii
witch-alder, Fothergilla gardenii
oak-leaf hydrangea, Hydrangea quercifolia
fetterbush, Leucothoe racemosa
swamp haw, Viburnum dentatum
arrow-wood viburnum, Viburnum nudum