Invasives Dystopia

I've been asked to give the keynote address to a regional gathering of Garden Club of America clubs in October.  The theme that the organizers chose for the gathering is "invasive plants," which gives me a lot of leeway for my talk.  I'm going to focus on introduced ornamentals that have escaped and become invasive pests.

One of the organizers wants to create a poster board of "bad actors," and she wants to include Japanese knotweed (Fallopia japonica) among the plants.  I needed to find images of knotweed for her, and on the way back from the grocery store yesterday I saw a perfect patch just begging for a photograph.  So, I parked and walked over to get some shots.

The area is on the floodplain of a small tributary to my creek just upstream of my preserve.  It is - to put it bluntly - an invasives hell.  An ecological nightmare.  A complete write-off.

The floodplain is an impenetrable thicket of Japanese knotweed.  It's 10-feet tall - the tallest knotweed I've ever seen.  But wait, there's more!  The knotweed is being over-topped by porcelain-berry (Ampelopsis brevipedunculata).  And, just outside the area where the knotweed is so thick, there's a thriving stand of purple loosestrife (Lythra salicaria).  About the only plant I didn't notice was mile-a-minute weed (Persicaria perfoliata), but it certainly could have been there amid the green chaos.

I will admit that bees were enjoying the scene - and not just non-native honeybees, but native bumblebees, too, so I guess the site is not a complete write-off.

Invasive Gulch

Knotweed in flower

Porecelain-berry is rapidly engulfing the trees in the background

The land is owned and managed by the municipal wastewater authority.  Although the site is at the intersection of two fairly significant roads, the wastewater authority doesn't do much to maintain the property.  They probably don't know what to do (repeated herbicide applications would be appropriate), but they do try to mow it down occasionally.  I've tried to talk to them about management, but they're in the wastewater treatment business, not invasive plant control, and I've gotten nowhere with them.

Knotweed (background) and purple loosestrife

Purple loosestrife (mostly) with a little porcelain-berry in the foreground

Of course, since the stream is a tributary to my creek and is upstream of my preserve, all of the propagules produced by these noxious weeds flow downstream and end up you-know-where.

The knotweed in the foreground is being over-topped by porcelain-berry

Porcelain-berry Is Bringing Me Down

Porcelain-berry, the kudzu of the North, on the periphery of my natural area

For some reason (perfect temperatures, soil moisture, carbon dioxide concentrations, or a synergistic interaction of all three), the invasive Asian vine porcelain-berry (Ampelopsis brevipedunculata) "exploded" in my preserve this summer.  The perennial vine is ever present, and always the biggest threat in the natural area.  When I first took my job 25 years ago, one of the first tasks I set for myself was to bring the plant under control in the most heavily infested areas, and I was really able to knock it back with several years' intensive mechanical and chemical control efforts.  But, as I said, this year it has re-surged with a vengeance. 

Porcelain-berry fruits in varying stages of ripeness

Porcelain-berry was introduced to the united States from eastern Asia, probably as a garden ornamental.  It's fruits are attractive for about two weeks in the fall, but the rest of the year the plant just looks like a sprawling grapevine - to which it is very closely related.

Once the plant escaped the bounds of gardens (undoubtedly aided by birds that eat its fruit and then defecate the seeds elsewhere), it found a perfect home in the Mid-Atlantic.  It grows up into the canopy, spreads out to capture sunlight, and blankets the trees supporting it, eventually shading the trees to death or ripping off their limbs when the weight of the vines becomes too much for the tree to bear, especially when covered in snow and ice in the winter.

Porcelain-berry flowers attracting a honeybee

Porcelain-berry is served by generalized pollinators, so it is not dependent on a specialized bee, wasp or bat to spread its pollen.  And, while it's an introduced species, our native North American songbirds (and white-tailed deer) consume it readily, helping to spread the plant across the landscape, probably because it is so closely related to the grapes that are already familiar to our native species.

The only insects I have ever observed damaging porcelain-berry leaves are invasive, non-native Japanese beetles, but they never become numerous enough to inflict real harm to the plant.  I suspect that even if the plant has a specific disease or insect pest that keeps it in check in its homeland, such a disease or insect could never be imported into the United States as a biocontrol agent because it likely would also attack commercial grapes.

A porcelain-berry rhizome

Porcelain-berry develops an extensive, thick underground stem or rhizome.  The rhizome grows through the soil and sends up shoots ever few feet or so.  An infestation of porcelain-berry may actually consist of only a few plants all growing from the same underground stems.  Cutting off a few of the above-ground vines hardly fazes the plant, which has plenty of resources stored underground.  The only feasible method of control is to poison the plant with a broad-leaf herbicide applied either to the foliage or directly onto the rhizome after an above-ground stem is severed.

One of my board members asked me to do a photographic inventory of land parcels on the periphery of the preserve that we might be able to acquire to add to the natural area.  I completed the inventory and prepared a PowerPoint program that I presented at the last board meeting.  In my remarks prefacing the presentation, I alerted the board members to note that every single one of the 10 parcels I had photographed that was not maintained as a meadow was completely overwhelmed by porcelain-berry.  The Vandals are at the gates, and the endgame doesn't look good. 

Porcelain-berry is really bringing me down; it's the last straw.  I have psychically and physically invested nearly half my life in the stewardship of my natural area preserve and, if anything, it is in worse condition now than when I started working.  Storm-water flooding is worse, streambank erosion is worse, white-tailed deer damage is stable but is not declining, the invasive non-native emerald ash borer is on our doorstep and will kill perhaps a third the trees in the preserve, and porcelain-berry (and other invasive vines) are, if anything, even more prolific than they were a quarter-century ago.  If I haven't already crossed the threshold, I'm close to the point of despairing about my professional career.