MUGWORT AKA Artemisia vulgaris

Mugwort is native to temperate areas of Europe as well as Asia. Historically this plant was used to cure so many ills that during the Middle Ages it was called "The Mother of Herbs". There are a number of different plants in the Artemisia family.  Of these, mugwort is the most common variety.  When you see the Latin word vulgaris incorporated into a Latin name for a plant it simply means common, or the most commonly found variety. In addition to medicinal use, the plant was used as a flavoring for beer before hops and it was and still is used in various foods where a somewhat pleasant but bitter flavor was desired.  Because the plant had so many different uses, it was deemed a necessity in North America.  Therefore, the seeds hitched a ride with passengers headed here as early as the 1600's.  Once mugwort arrived on our shores it readily colonized, and then it naturalized.  This plant rapidly creates a monoculture.  

I have actually watched it happen right under my nose! The bridge spanning Merrick Brook on Station Rd. was replaced around 12 years ago.  The soil was disturbed in the process and after the work was completed, a grass seed mix was spread to suppress erosion and presumably weeds, but somehow mugwort sprouted in the disturbed soil.  I think because the plant so strongly resembled ragweed, I did not notice its presence.  Once the plant had begun to invade my yard and gardens, I looked at it more closely and realized what it was.  By that time, it had begun to spread significantly along both sides of the road.   When I tried pulling it out by the root, I realized what an extensive rhizome system it had. It is extremely difficult to remove the entire root system from the soil without leaving a portion behind.  At first, I thought perhaps cutting the plant back would help keep the plant contained, but by the time I got out my weedwhacker the plant had developed tough reedy stalks, and the mugwort just laughed at me.  After years of growing unchecked, the mugwort colonies along both sides of the bridge appear to be bursting through the guardrails. 

Large colonies of this plant can be seen growing along roadsides all over town.  Like many of the plants I've been writing about, mugwort contains allelopathic compounds, chemicals exuded from various parts of the plant which prevent other plants from growing nearby.  Despite its legitimate uses, mugwort has definitely achieved outlaw status, not only because it chokes out native plants, but also because it does not support any of our native wildlife.  The pungent medicinal fragrance contained in its foliage deters grazing animals and insect life from consuming its leaves.  Its flowers pollinate by wind therefore mugwort does not support any of our native nectar seeking insect life either. The plant rapidly spreads from its creeping rhizomes as well as from seed with one plant producing up to 200,000 seeds per year!  Fortunately, not all of these seeds will be viable, but then it really only takes one to germinate and rapidly create a new colony.  

HOW TO REMOVE

Hand pulling is an option for small infestations, again best done after a good soaking rain which softens the soil making rhizome removal easier, also gloves and long sleeves are recommended due to potential dermatological reaction.  Larger plants have an even more tenacious rhizome then their younger counterparts making hand pulling quite a chore.  Mowing the plants back early in the season and then smothering the colony with heavy duty landscape fabric or a layer of cardboard followed with a very thick application of mulch may help but the area will require monitoring. Mowing the plants with a brush mower in mid-September before seeds mature will at least eliminate seed dispersal. A foliar spray containing triclopyr applied on the mature plant seems to be one of the more effective treatments recommended for this plant's permanent eradication. 

 GARLIC MUSTARD AKA Alliaria petiolata

Garlic mustard first year

Garlic mustard second year

This is a plant found just about everywhere along the roadsides and in the shady forest understory throughout Scotland.  It was brought here because it is delicious and is proof positive that you can definitely have way too much of a good thing!  If you look closely, you will find wherever garlic mustard grows it forms a monoculture.  Few if any other plants grow among its ranks.  It has a sort of superpower, actually the same superpower shared by numerous other invasive plants, and even other biological organisms for that matter.  It is believed that garlic mustard contains allelopathic compounds.  Allelopathic compounds are chemicals found in a plant's leaves, roots, flowers or stems.  The compounds are toxic to other plants, preventing their germination.  They are also toxic to the fungi whose mycorrhiza (essentially a fungi's root system) help to nourish native plants and trees.  In the case of garlic mustard, these compounds are thought to be found primarily in the plant's root system.  Garlic mustard is native to Europe and was brought here as a culinary and medicinal herb.  In the United States it was introduced in Long Island in 1868 and has since spread throughout our country.  As a non-native invasive species, it has few natural enemies here.  Its early spring germination helps it to fill the forest floor, shading and crowding out many of our native species. The plant is biannual. The first year the plants remain short and there is only foliage.  The second year the plant produces clusters of tiny white flowers, which are attractive to several native pollinators.  The flowers are followed by an overabundance of tiny seeds.  The tiny seeds are easily spread throughout the forest on the feet of humans or animals; therefore, Garlic Mustard is frequently found growing along trails.   It is a forager's dream since all parts of the plant are edible, and the plant is easily identified by the garlicky odor emitted when the leaves are crushed. The leaves are best taken from the young short first year plants, flowers and seeds from the tall second year plants. The roots from the plants are said to be rather similar substitution for horseradish root.  Recipes are3 readily available on the internet.  It should go without saying that you want to forage plants for food or medicinal use only if you can identify them with absolute certainty.  In addition, be certain to forage only in areas where you are certain there has been no chemical treatment applied. When foraging garlic mustard use caution so as not to spread this plant's numerous seeds!  

HOW TO REMOVE

The plant is very easy to pull out by the roots.  To be certain of the plant's demise, it is best to place the pulled plants in a black plastic bag exposed to the sun for at least a week.  Do not leave pulled plants on the ground in exposed piles as they will continue to grow and produce flowers and seeds.  The seeds can remain viable for up to four years so you will need to be persistent in pulling the plant for several years.  Garlic mustard can also be eradicated using Glyphosate at a 2% solution.  Other foliar sprays are also effective. 

There is experimental biologic control in the form of an aphid that was first discovered in the U.S. in Ohio in 2021.  It is appropriately called the garlic mustard aphid AKA Lipaphis alliarae.  Like the garlic mustard plant, the aphid is native to Europe.  The cause of its appearance in the United States remains a mystery.  It is presently being carefully monitored. Since its discovery, the small gray aphid, which has a raised pattern on its back that strongly resembles a grenade, has been spotted devouring Garlic Mustard in several other states.  At present there are isolated populations of this epicurean insect in Connecticut, so be on the lookout.  

My last thought here is that our town has quite a few large tracts of privately owned acreage.  You do not necessarily have to get involved with a group to improve our town's landscape.  Just enjoy a few hours walking your land and be observant.  Removing some of these plants from your own land really will make a difference to the entire town!

 

WHAT ABOUT POISON IVY? AKA Toxicodenron radicans

When we think about plants that are invasive, it is awfully difficult not to include our native plant poison ivy.  Perhaps I am just seeking revenge in posting it on this blog.  While it is not true of many, there are a few native plants that share some of the aggressive growth characteristics that non-native invasive plants have.  Poison ivy is one of them.  It is a plant most of us despise because of the itchy painful rash (contact dermatitis) caused by coming in contact with the oily and difficult to remove urushiol contained in its foliage, stems, roots, flowers, and seeds.  All parts of the plant contain this substance.  Urushiol is present during any stage of the plant's growth.  It is also present when the plant is in dormancy, and even when the plant is dead. I have never had a summer go by without getting a horrible rash from poison ivy.  It is not that I can't identify the plant, it's more like I think maybe I can get away with it just this time by wrapping the stem with a big maple leaf and pulling it out quickly.  Having lost the battle just about every year, I have become somewhat of an expert on treatment for the rash.  If you happen to come in contact with this plant accidentally, I highly recommend using Tecnu products. In my opinion, Tecnu Poison Ivy & Oak Scrub is a miracle worker. It will wash off the oily urushiol if used shortly after contact.  It will also help to relieve itching and help to dry any rash you end up with from contact and not washing off in time. 

Have you wondered why there seems to be more poison ivy these days than in the past?  Well, this plant happens to be one of only a few native plants that are capable, like many non-native invasive plants, of taking advantage of the warmer temperatures and the higher concentration of carbon dioxide in the atmosphere.  These changes are propelling poison ivy to grow into the lush vines that festoon many of the trees along the edge of the wood line.  This new enhanced version of the plant actually produces a more virulent version of urushiol, causing an even more severe reaction for us humans. 

It is fine to eliminate poison ivy if it is growing in a place where you do not want it to be.  It is under absolutely no threat of becoming endangered.  If it is growing in a place that you can avoid contacting it, it is best to just leave it alone. This plant is a very good food source for our native wildlife.  The vine has small white flowers that native pollinators visit.  The resultant seeds that form remain on the vine most of the winter making them an available food source for birds that choose to spend their winters here with us.  Deer, black bear, raccoons and other wildlife graze on the plant's foliage with no negative effect from the urushiol.  In fact, most humans, some primates, Guinea pigs, and most bats are the few species plagued by contact dermatitis from poison ivy's coating of urushiol.  This is due to the fact that none of these mammals are capable of creating their own vitamin C.  Early primates were capable of doing so, but as they continued to evolve, and eventually evolved into homo sapiens, that ability was lost.

HOW TO REMOVE

For small infestations, hand pulling using waterproof gloves and protective clothing can be helpful.  The plant has a long trailing rhizome system with periodic clusters of roots along its length.  This eventually connects to a tap root, so it is pretty difficult to pull the whole thing.  If the plant is growing on the ground along a wood line, simply mowing it repeatedly will control it well enough. Both sheep and goats can and will eat poison ivy with no negative effects, so they can be quite helpful in controlling its spread as well.

For larger infestations, especially those that are climbing in trees, the recommended herbicides are Glyphosate or Triclopyr.  Glyphosate can be used as a foliar spray.  Spraying is best performed later in the plants growing season when flowers are forming.  Keep in mind that Glyphosate is a non-selective herbicide meaning it will kill other broad leaf plants as well as grasses.  Another method is to cut the vine and paint the cut portion with a concentrated form of glyphosate.  An herbicide containing Triclopyr is also recommended.  As with Glyphosate, you can apply it as a concentrated version to the cut vine to prevent regrowth.  If using any herbicide as a foliar spray, spray on a calm day when the plant has reached full leaf growth.  If using Triclopyr as a foliar spray avoid spraying it on the trunks of trees, especially those with smooth bark or on the bark of trees with smaller diameters, as it can be absorbed through the bark and will harm the tree.  Triclopyr will not harm grasses.  DO NOT BURN POISON IVY!  Smoke and ash from burning this plant can carry the urushiol not only to your skin, but also to your mouth, eyes, nasal passages, and lungs.  THIS CAUSES A VERY DANGEROUS REACTION!

 

ORIENTAL BITTERSWEET AKA Celastrus orbiculatus 

Welcome to the Scotland Invasive Plants Working Group.  If you have some time today, click on some of the other informative links. Thank you for your interest in eliminating invasive Oriental Bittersweet from our town land and your own land. 

A native of Japan, Celastrus orbiculatus was brought to the United States as seeds in 1879 by Samuel Parsons who it is believed purchased seeds from Thomas Hogg Jr who was living and working in Japan, and whose father had a horticulture business in New York. The seeds were grown at the Arnold Arboretum outside of Boston, MA. After about ten years, the plants were offered for sale by Samuel Parsons who operated Kissena Nurseries in New York. The plant appears in one of their nursery catalogs from the 1880's, where it was described as very decorative especially during the winter months with its colorful display of yellow and orange seeds extending along the entire vine.  Although it remains a very decorative vine today, its colorful and prolific yellow capsules with their orange seed containing fruits have scattered over the years and have grown into the tangled vining plants that appear just about everywhere in our landscape. At this point our fields and forest edges have become incredibly overgrown with Asian bittersweet. Its vines have climbed into the treetops killing trees by wrapping around them tightly and girdling them or with their weight downing tree branches and even toppling older growth trees.  As more Bittersweet seeds fall new plants sprout and continue forming an increasingly impenetrable tangle that shades out native plants. The reward for removal of this plant is allowing native species to return to the landscape and protecting trees at the woodland's edge. You will also realize improved esthetics given the ability to see more clearly into a woodland unencumbered with a tangled mass of invasive vines.  This will also allow for easier access for recreational activities.

HOW TO REMOVE

The good news is that with a bit of persistence, this plant is fairly easy to control.  Bittersweet can actually be eliminated from areas where it has become troublesome.  It is a matter of cutting the trunk portion of the bittersweet back repeatedly while also cutting the "tree ladder". The tree ladder being the lower branches on any trees growing near the vine that make it possible for the vine to climb into the tree canopy.  Though it can be done any time of year, it is sometimes easiest to begin the process during the winter months when the vine is most easily accessible. At this point cut the trunk of the vine and any surrounding lower tree branches.  There is no need to physically pull the vine from the tree branches.  In fact, doing so could damage the tree. The upper portion of the vine will die back and disintegrate surprisingly quickly once its connection to the roots has been severed.  If you can pull out the root after cutting the vine, that will be helpful in the plant's faster demise.  Repeating the process of cutting the bittersweet as it attempts regrowth several times during the summer months will continue to sap the plants strength.  Your persistence will eventually kill it.  If you want to ensure that this pant does not regrow from the cut stumps simply paint them with a concentrated application of herbicide.  Eventually you will be left with only young Bittersweet plants sprouting from fallen seeds, and these will be quite easy to pull out by the roots.  They have a bright orange root system easily recognized.  I often hang the young plants I remove in the branches of a nearby shrub where they will they dry out and lose their vitality.  Of course you can also collect them, bag them up and dispose of them in the landfill. 

This invasive plant has no natural predators, so it is up to us to keep it contained within our landscape! 

 

 

BUSH HONEYSUCKLE AKA Morrow's Honeysuckle, Lonicera morrowii, or Lonciera tartarica, or Lonciera bella

There are a couple of invasive or potentially invasive bush honeysuckles living among us.  Technically they are or at least were two different species Lonicera morrowii native to Japan, Korea, and Northeast China, and Lonicera tartarica native to Eurasia.  Both were imported to the United States as ornamental shrubs.  The two are related and have similar growth habits, both reaching an average of 10 feet tall with a wide upper crown. These bush form honeysuckles are not to be confused with Japanese honeysuckle, also considered invasive, but which is a vine rather than a bush or shrub. As I am researching for this blog entry, and pondering which of the bush species we have, or if we actually have both, I learned that the two have actually cross bred on their own in a method called artificial hybridization (a cross consisting of two different species). The cross bred plant is called Lonciera bella. In mid-spring, even though I know I should, it is difficult to hate these invasive family of bush honeysuckle plants.  This is the time of year, early May, when the bushes are loaded with incredibly fragrant flowers.  When in bloom, during a span of a good two weeks, you can't help but detect their powdery fragrance in the air. The flowers form in clusters starting off white and maturing to pink or yellow.  After the flowers are done blooming, the red or orange fruit forms, also in clusters.  The fruit is just as prolific as the flowers and therein lies the problem.  As the fruit falls to the ground, the seed contained within germinates.  The colorful fruits are also carried away by birds or small mammals, The seeds within the fruit pass through their digestive tract and are later deposited elsewhere amid their droppings.    As a rule, bush honeysuckle prefers to grow in open sunny fields or on the forest edge.  Birds and animals transport the seed further into the woodland where the bush will grow if there is an opening in the tree canopy that lets in the sunshine.  If growth from seed dispersal is successful bush honeysuckle will colonize that forested area too.  I have personally witnessed this plant rapidly take over former pastureland and also witnessed its creep into the adjacent forest. 

HOW TO REMOVE

The plant has a relatively shallow root system, making smaller examples fairly easy to pull especially after a good saturating rainfall.  If there is not an overabundance of bush honeysuckle to tax your strength, larger plants can be removed by cutting the plant's branches back and using a pickaxe or similar tool to undermine the root collar.  Sounds fun huh?  If you can get under it, you can remove the shrub with the root collar attached leaving the remaining roots behind.  After all that work it is good to know that at least this plant will not grow back from the long trailing parts of the roots that remain in the ground.  

If the infestation is larger, there are several solutions you might consider.  During the plants summer growing season, cut back all of the branches as low to the ground as possible.  This can be done with loping shears, or with a battery or gas-powered brush cutter, the gas version is cleverly nick named a gas goat! After cutting back the shrub, it is essential that you treat the remaining cut portion of the branches with an herbicide such as glyphosate, otherwise the shrub will aggressively grow back, and all of your hard work in cutting will be for naught.  The herbicide will prevent regrowth of the branches.  If an infestation is especially heavy an autumn foliar application of herbicide is recommended.  The plant keeps its foliage after any native plants or trees have died back so a late in the season treatment will more specifically target bush honeysuckle and spare any native species.  You will need to keep an eye on the area and perhaps treat a second time, but rest assured, you will gradually win the fight.  I don't want to leave out goats as another possibility here.  Provided bush honeysuckle has not been chemically treated prior it is safe for most goats to consume this plant in addition to other foods that generally in their diet.  

JAPANESE KNOTWEED AKA  Reynoutria Japonica, Fallopia Japonica

Almost every time I search for or take a photograph of the "invasive plant of the week" I am surprised by the plant's decorative potential!  The first photo is a good depiction of what the plant looks like at its present stage of its growth.  The second photo shows the mature plant in flower.  Although commonly called Japanese knotweed this plant is native to all of Eastern Asia. When in bloom the plant is positively loaded with gorgeous foamy white flower spikes that are attractive to pollinators.  An interesting note is that the young shoots and leaves of this plant are edible.  The shoots have a tart flavor similar to rhubarb and can be used as its substitution in recipes.  Should you be interested, recipes for knotweed, including knotweed wine, sorbet, and chutney can be found on the internet.  If you are choosing to harvest this plant for consumption, be certain you are harvesting the correct plant and that it is not from an area that has been treated with chemicals!

How did this plant arrive on our shores?  Female plants, thought to be sterile, were first introduced in the prestigious Kew Botanical Gardens in England in 1850. During the 1880's it became a desirable exotic plant for inclusion on the property of several expansive Long Island, NY estates.  It appeared as an ornamental plant in nursery catalogs until the latter 1930's.  Even then it was under watchful surveillance as a suspected outlaw and garden escapee.  

How did this plant arrive in Scotland, CT?  One of its adapted uses was for erosion control.  Stands of it were installed on highways and state roads.  This is likely the cause of its present bounty along some of our roadsides in town.  When traveling through Scotland on our town and state roads, you can't help but notice vast colonies of knotweed so dense that nothing else grows among it.  The reason for that is that it, like some other invasive plants, it has an allelopathic superpower.  The plant's roots and other decaying plant parts exude chemical compounds that prevent other plants from growing in its midst.  The plant also has dense lush upper leaf growth, keeping any brave potential competitors from finding the sunlight they require to grow.  This is how Japanese knotweed quickly creates a monoculture.  It crowds out native species that many of our native insects and animals require to thrive. You may wonder, how did only female plants reproduce so prolifically?  There are a couple of answers to that question.  One is that are other several species of knotweed and if one of these happens to be located nearby, there is a potential for cross pollination, which would create viable seed.  This plant, however, spreads primarily through its root system, technically called a rhizome system.  Rhizomes are roots that grow horizontally periodically sending up new growth. In the case of knotweed, these rhizomes are hardy enough to penetrate through any small cracks in a house foundation or any pavement potentially causing severe damage.  In some areas, the presence of this invasive plant is actually having a detrimental effect on real estate values.  Although the plant goes dormant in the winter months and temporarily dies back when there is a spring freeze, the rhizomes remain viable underground.  Even if plant growth is suppressed and no additional nutrients are added, it is said that the rhizomes are capable of remaining viable for up to 20 years!  Any small bits of this powerful rhizome system accidentally transported by a snowplow, brush cutter or unintentionally by a garden shovel will readily form a new ever-increasing colony.  If this plant colonizes along our waterways, the diverted water flow caused by dense stands of Japanese knotweed can cause flooding and potential bank erosion.  As riverbanks erode, segments of the plant's rhizomes could be transported downstream.  Rivers brooks and streams are a virtual highway for the plant to follow. Elimination of this plant should definitely be a priority!

HOW TO REMOVE

Take a deep breath!  This is going to be a difficult but not impossible task.  It is one that will likely involve a combination of techniques possibly including the use of herbicides.

If you want to try a method that does not use herbicides the present recommended method is to cut the plant back three times during its growing period.  Once in June, again in July, and last in late August.  The repeated cuttings are meant to keep the plant from flowering.  Cut as low to the ground as possible.  The stem has what look like joints or notches which are called nodes.  You want to cut the plant beneath the plant's lowest node.  Cutting the plant numerous times also helps to reduce the plants energy transfer to its rhizomes.  After cutting, the knotweed patch can be covered with black plastic carefully weighted around the edges.  The cut stems should be placed in contractor bags and disposed of in regular trash.  Do not compost them, as any pieces of attached rhizome could sprout in your compost pile! This method of removal will need to be repeated for at least three years.  Continue to monitor the area as this plant can be very persistent. 

If you are comfortable using herbicides, The recommended method is to cut the plant back to 2 to 3" in late May or June, and then let it grow until August.  Spray before the plant flowers using glyphosate with an added surfactant or with triclopyr.  Many pollinators feed on this plant so spraying either before flowers form or after the flowering stage is complete is essential so as not to harm them. Cutting the plant back in the spring reduces the height of the plant, therefore the amount of chemical needed for coverage.  The same protocol will need to be repeated the following year.  After the second year of treatment, plant the area with some native species to reduce the growth of Knotweed.  You will likely need to continue treatment every two years following the second treatment.

Biological Control:  An insect called Japanese Knotweed Psyllid or Aphalora itadori was introduced in 2020 as a possible biological control method.  The insect is host specific to Invasive knotweed.  During all of its life stages, the insect consumes the sap from the leaves and stem.  This in theory weakens the plant.  In the United States in 2020, several releases were done in areas including Rhode Island and Massachusetts.  Other releases in the UK and Canada done back in 2010 have resulted in populations of the Knotweed Psyllid having established a presence in that area. It remains to be determined how successful the release of this insect in the United States will be.