Japanese Knotweed Just Emerging

I recently came across a post on a Facebook group regarding invasive plants.  A person who has been attempting to eliminate Japanese knotweed from their landscape is apparently having some luck using an herbicide treatment and the method suggested by another Facebook group called The Japanese Knotweed Support Group, a group designed for people dealing with this terribly invasive plant.  My membership to this group is still pending at this time.  Should you wish to join, here is a link to that group Worldwide Japanese Knotweed Support Group |.  

Below is a copy of the Facebook post I came across recently.  It includes a method recommended by the support group. The person who posted tried the recommended method with some pretty good success. 

"I have some new sprouts coming up this year as it is a multi-year process but after spraying once last year in late September I can tell you the difference is ASTOUNDING. I really just followed the recommendation of the worldwide Japanese knotweed support group. I ordered glystar 41% concentration glyphosate which already has surfactant in it. I used a battery-operated backpack sprayer and calculated how much water to add to it to make the glyphosate a 2% concentration, and I added a couple capfuls of blue lawn dye (got everything on Amazon). I suited up with proper PPE including a mask and eye protection and used a ladder to spray the really tall stands. I tried to hit as many knotweed leaves as I could physically get to. "

This is a copy of my earlier post on Japanese knotweed 

Monday, May 5, 2025

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 such as Joe Pye weed 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.

Bulblets

 Dicentra cuclaria AKA Dutchman's breeches, Little blue staggers

You can't help but laugh when you see all the cute white pantaloons hanging off this plant!  It is a plant native to Connecticut and New England, a perennial with an early spring bloom.  Both the flowers and the finely compound lacy fernlike leaves are attractive.  It is a perfect native plant for a shaded or semi-shaded spot with rich organic soil. Keep in mind that the leaves and flowers will die back completely after the bloom period so the plant will virtually disappear as the season progresses.  The bulblets in the ground will remain viable and the plant will reappear the following spring. Although the flowers do not have a fragrance, they are attractive to bumblebees.  The flowers are designed so that the bumbles separate the petals with their front legs and gather pollen from the anthers with their center legs. Pollinated flowers eventually produce a long pointed seedpod. The seeds within have sweet eliasome coating prized by ants who bring the seeds to their colony where the coating is consumed.  Ants being the good housekeepers that they are, will discard the seeds to their nutrient rich refuse pile after the coating is consumed.  There the seeds will eventually germinate.  This process, called myrmecochory, is shared by numerous plants.

I do not recommend using this plant for any purpose medicinally as it contains dangerous compounds.  However, Dicentra cuclaria does have a history of medicinal use by Native Americans and early European settlers including use as a cure for Syphilis.  The plant which is now considered to be in the papaveracae family contains isoquinoline alkaloid compounds.  These alkaloid compounds are the source of the plant's other common name Little blue staggers.  This is not a safe plant for livestock to graze on as the compounds contained can cause drunken staggering and even death, hence its other common name.  This is not a safe plant for humans or other animals to consume any part of!

 

Viola sororia AKA Common Blue Violet 

I love when in early spring our back yard becomes blanketed with violets!  These beautiful wildflowers are called Viola sororia.  They are a plant native to Connecticut, one that is not only beautiful but edible. There is a close imported look-a-like called Viola odorata, a variety from Europe.  Viola odorata shares many aspects of our native violet but its flowers have a pronounced sweet fragrance.  Viola odorata flowers are considered just as edible as our native violets. Most species of viola are edible including Johnny jump ups and other pansies. Historically our native Viola sororia was a source of both food and medicine for Native Americans. The flowers which range in color from white to various shades of purple can be eaten freshly picked.  Simply toss raw flowers into salads where they will add a colorful accent. Fresh flowers can be frozen into ice cubes or pressed into a soft cheese such as brie.  The flowers can also be preserved for a time as crystalized violets.  Crystalized violet flowers are a delicate confection impressive when used as a decoration on a cake or a garnish floated atop a drink. To make them, simply dip the flowers in slightly beaten egg whites, then dip in granulated sugar. Place the flowers on a parchment lined cookie sheet in a slightly warm oven until they are dry to the touch.  Stored in airtight containers in a dark place, they will keep for several months before the color fades. Just today I found out that the heart shaped leaves of this plant are edible as well!  The leaves can be steamed like spinach.  Although I have yet to try the steamed leaves, the flavor profile is said to be similar to peas, so I imagine slightly sweet. It is advisable to wait until the plant is in bloom before gathering violet leaves for consumption so that you are certain that you have accurately identified the plant.  Please be certain any plants you gather have not been treated with chemicals!

Here is an interesting fact regarding pollination and reproduction of this plant.  The plant forms two types of flowers, the above ground flowers that we are all familiar with.  These are the flowers visited by the pollinators of which there is a diverse group including honeybees, bumblebees, and various beetles, flies and moths.  However, to assure its continued existence perhaps in the case of an especially cold year with lack of insect pollinators, the plant also produces a group of self-pollinating flowers that lie beneath the soil.  These flowers never actually open but do produce seed. If you have ever pulled out a clump of invading violets from your garden, you may have observed some of these closed flowers growing among the rhizomatous root system.  The technical term for the underground flowers is cleistogamous flowers versus the above ground flowers which are chasmogamous flowers. 

 

Erythronium americanium AKA Trout Lily, Yellow Dog Tooth Violet  

This a beautiful little flowering plant is native to Connecticut, and a harbinger of spring.  The leaves have a mottled splotched pattern as well as a shape that much resembles the body of a trout hence Erythronium americanium's most common name trout lily.  You will find this plant growing on the damp forest floor during the months of April through May where it takes advantage of the sunlight before the forest canopy fills in.  The plant is a reluctant bloomer with only a fraction of plants producing blooms during the month of April.   A short time after any blooms fade the foliage of all the trout lily plants dies back for the year.  The leaves turn yellow and wither away returning again the following April. 

 Many of the trout lily colonies you encounter in the woods can be hundreds of years old.  When you encounter a large colony, you will likely notice only one or two plants with flowers.  Because the flowers are one of the first in the season to bloom, they are pollinated almost without fail by bees that are extremely hungry after a long winter.  A great deal of energy goes into producing any of the flowers you see. It may take up to five years of stored energy to produce it.  The stored energy comes from the process of photosynthesis, which these days may be best explained using the analogy of a solar panel connected to a battery. A solar panel gathers energy, and when connected to a battery any of that energy not expended for other things is stored within the battery for future use.  In the case of the trout lily, it can take up to five years of stored energy finally allowing for the production of a single bloom making you wonder how a colony of trout lilies can be so massive when there are so few flowers resultant in so few seeds.  Trout lily plants have a second method of reproduction, an unusual cloning method.  Each plant sends out a long slender threadlike stem called a dropper.  These droppers grow up to 10" long.  As they grow, they turn a 45-degree angle and burrow deeply into the ground.  After planting themselves the droppers gradually form a corm (sort of a bulblike structure) that grows into another plant.  This is how trout lilies are able form a dense carpet on the forest floor.  The seeds that form from the flowers are also viable.  Several are produced within a capsule.   They are designed to be planted by ants.  Each of the seeds within the capsule is coated with a sugary substance irresistible to an ant.  They carry the sugar-coated seed home to share with their buddies. After the coating is consumed, the seed gets tossed in their trash pile where it eventually germinates creating another trout lily plant that over time given the right growing conditions can develop into a new colony. The ant feeding process is called myrmecochory.  A variety of plants share this method of survival.   

 

Hate To Rush Things but Spring Now Please!

I am so thankful for the folks who put together the 10-day forecast.  I don't know what I would do without them.  I study that forecast with great anticipation every morning during the winter.  I frequently look several times a day, in hopes it might improve. Today, just when I didn't think I could take another day of ridiculously frigid snowy weather, and snow squalls, I see there is a light at the end of the tunnel.  Finally, a warming trend is included in the forecast, and it seems to include several days predicted to be in the 40s! Combined with days getting noticeably longer, and the occasional calls of a few very brave early voyaging birds, it gives me hope that spring may be in the air!  It may be time to at least consider emerging from hibernation and pondering some potential tasks for the days ahead. One of the first I'm contemplating, once the snow cover melts back some, is cutting the bittersweet vines as low to the ground as possible. I promised one of my partially strangled sycamore trees I would do that last year, but time got away from me. Late winter is a great time to accomplish the job as there is no competing vegetation and best of all no ticks!  It is a fairly easy job, a good way to break into the gardening cycle slowly.  There is no need to remove the vine from branches of the tree. Once the vine dies back it becomes light and fragile and it will lose its chokehold.  There is no need to paint herbicide on the cut portions at this time either.  Herbicides aren't effective during the spring months.  Plants are busy sending stored nutrients from the roots to the upper story beginning to produce foliage during the spring months.  Herbicides are always best applied when a plant has fully matured foliage.  It is at that point when the transfer of nutrients reverses and nutrients are transferred from the leaves back to the roots.  This allows the herbicide to be carried to the roots along with the nutrients which effectively kills the plant.  Sometimes herbicides aren't even needed.  Provided you have the time and patience, just keeping up with cutting the bittersweet vine, and pulling it out, when possible, will in time be enough to control an infestation. Cutting the lower branches of adjacent trees also helps as it deters the vine from climbing them.  Yup, after my second cup of coffee, I am actually looking forward to the physical aches that the spring tasks will bring!  In addition to the extended forecast, I am especially grateful for caffeine and Aleve!

 

Brush Fence

Somewhere along the line, I came across a photograph of a brush fence and thought what a good idea!  There are so many dead trees in the woods everywhere, and while there are many ways to dispose of the resultant branches, this one seems less labor intensive then most, and it creates an attractive border.  With the vertical posts in place additional brush can be added as it falls.  Best of all it makes a great home for the tiny creatures that populate the woods.

 Connecticut Flower and Garden Show

Experience spring even if it is only for a day!  The Connecticut Flower and Garden Show will be a great place to get some gardening ideas for the coming year!  The show will be running Thursday through Sunday February 19th - 22nd at the Connecticut Convention Center in Hartford on Columbus Blvd.  For more detailed information regarding hours, admission prices, parking options, and exhibitors, I have provided a link. https://ctflowershow.com