Showing posts with label mile-a-minute. Show all posts
Showing posts with label mile-a-minute. Show all posts

Saturday, August 01, 2020

Mile-a-Minute Vine in Princeton

Each year I conduct a solo campaign to keep the highly invasive weed Mile-a-Minute out of Princeton. It's a prickly annual vine that grows each year from berries produced the year before. Knock it out before it produces berries, and eventually there will be no berries to sprout. Otherwise, the infestation will grow and birds will spread the berries across all of Princeton, to spring up in backyards and vex homeowners with its thorns and rampant growth.

I know of two infestations--one at the Princeton Battlefield, the other down off West Drive on the gravel road to Rogers Refuge. Yesterday, passing by Princeton Battlefield, I stopped to uproot what Mile-a-Minute I could find and leave it on the lawn to dry in the sun. Like most annual plants, it has whimpy roots and can easily be pulled, wearing a good pair of gloves.

Princeton Battlefield has a remarkable history, which makes it all the more remarkable how ahistoric the landscaping is. Non-native turf is surrounded by giant kudzu-like topiaries of non-native porcelainberry vine growing over the native dogwoods that were proudly planted for the 1976 bicentennial. There's little hint of what the Clark Farm looked like on that fateful day in January of 1777. The lack of botanical context doesn't fit with the people and era the Battlefield is meant to celebrate. Plants were important to George Washington and other leaders of his time. They were farmers. It's not coincidence that the United States Botanic Garden was built to stand next to the U.S. Capitol building. What grew upon the land mattered back then. They didn't mow the lawn and think their work done.

Seeing a landscape so invaded and out of balance, I sometimes imagine a hospital with no doctors or nurses, only custodians dedicated to keeping the place clean. The patients are on their own, unless a volunteer doctor happens by to treat some localized infection. That's the situation in the vast majority of our landscapes, cared for by custodians armed with raucous mowers and leaf blowers, oblivious to the complexities of nature and its needs. 

In the meantime, I pull the Mile-a-Minute, trim back some small portion of the porcelainberry vines so the dogwoods might live another year, and wonder at the world's disconnect with nature.

The two photos show 1) porcelainberry vines overwhelming a dogwood tree, and 2) another sea of porcelainberry in which only the similarly invasive Canada thistle can manage to lift its pink flowers above the swarm.

Tuesday, October 03, 2017

Wanted: A Few Good Herbivores

If you encounter a book or article that claims that, surprise!, invasive species aren't such a big problem after all (a few were written over the past decade), you'll probably find no mention of herbivory. They'll say that invasive plants are being falsely maligned, because actually they do wonderful things, like provide berries and nectar for wildlife. But it's to the plant's advantage to have its flowers visited and its berries consumed. What the plant doesn't "want" is to be eaten, and therein lies the problem with plants that become invasive. For whatever reason, be it an invasive's chemical defenses or ingrained dietary habits, the wildlife tend not to eat them.

Nature depends on consumption to keep things in balance. We love nature for its beauty and variety, but behind the scenes there's a whole lot of mastication going on. Take away predators and the deer population explodes. Introduce a new plant that the wildlife won't eat, and there's potential for that species to make habitat less and less edible as it displaces the natives. To fill this void in consumption, people have had to play the role of herbivores. What we do at Herrontown Woods, as we cut down dense groves of winged euonymus and other nonnative invasive shrubs, is to play the role of the missing herbivores, using our loppers for teeth.

There's some pleasure in the work--pleasing vistas created, serendipitous discoveries. But all things being equal, it would really be nice if the resident wildlife could show some flexibility in food preferences and fill the void in consumption. Invasives, after all, represent a huge, untapped food source for any animal willing and able to broaden its palette.

Given how much work it would be for humans to play the role of herbivores in the forest, any evidence of wildlife gaining an appetite for invasive plants stirs some hopefulness.

For instance, an invasive honeysuckle shrub was recently found stripped of its leaves. A closer look revealed something had been hard at work, its mandibles outshining our loppers: the caterpillar of a snowberry clearwing moth, also known as the "hummingbird moth" or "flying lobster", for its capacity to hover in front of flowers as it sips their nectar. Maybe if we had more summer wildflowers for the adult moths to feed from, their caterpillars would help control the populations of bush honeysuckle in Princeton's preserves. Nice to think, anyway.

And what's this orange plant growing on a dense expanse of invasive mugwort that grows as a monoculture along the gas pipeline right of way in Herrontown Woods? Dodder is a parasitic plant with little capacity to gather energy from the sun. Instead, it wraps itself around other plants and sucks out their juices.

Usually, its impact is small, but this must have been a particularly good year, because a sizeable patch of mugwort was sucked dry.

If only we could get the dodder (genus Cuscate) to preferentially neutralize the mugwort all along the right of way, some diversity might return. Again, a nice thought and tall order.

A new invasive trying to gain a foothold in Princeton is mile-a-minute vine, with a distinctive triangular leaf, a prickly stem, and a growth habit to match its name. Another post shows how invasive this annual vine can be , on farms just outside of town. Fortunately, after weeding out a small population back in 2007, I know of only two patches currently growing in Princeton, still small enough to control and hopefully eliminate altogether.

One's at the Princeton Battlefield. This year's growth was pulled out in early summer, and when checked in late August, the patch had only managed to produce a few leaves, all of which were being very effectively munched on by a weevil intentionally introduced to the U.S. to bring this rampant new species under control.

Ah, I concluded, to control mile-a-minute vine, simply reduce the patch in early summer, leaving enough for the weevils to sustain their population on. Their appetites appeared to be sufficient to prevent any flowering or fruiting that could lead to the patch spreading elsewhere.

Nice concept, but it wasn't working at the other site, down along the driveway into Rogers Refuge, where the vine had sprung back up, flowered and fruited, undeterred by the minor nibblings of the weevil. That patch had to again be pulled out by hand.

Another discovery was the work of the Ailanthus webworm moth, which had completely defoliated a young tree of heaven near the parking lot of Herrontown Woods. The moth, like the tree, is an introduced species.

If you have flowers like boneset growing in your backyard, you may be helping the adult moths to prosper.

Here again, though, the larvae have thus far been seen only on very young trees, with larger ones largely left untouched.

These are glimmers of hope, sprinkled across Princeton. It will take some concerted mastication by as yet unnamed herbivores to stem the tide of rapidly spreading species like porcelainberry, callery pear and stiltgrass--a giant uneaten salad that grows by the year. A little salt and pepper, perhaps?

Wednesday, July 05, 2017

Mile a Minute--A Wave Growing Across NJ's Countryside

You can spot it a mile away. Early summer, and already this annual, thorn-covered vine called Mile-a-Minute is rising like a wave along fencelines in New Jersey's countryside. Thus far, in my ramblings around Princeton, I have found only two tiny patches--at the Battlefield and along the driveway into Rogers Refuge--both of which have been knocked out the past two years. Is this sort of early intervention and annual followup worth it? The answer becomes abundantly clear just outside of town, halfway to Hopewell, where Mile-a-Minute vine is demonstrating just how much of a prickly menace it can be if not caught early.

It's a plant that seeks to be seen everywhere, and with all the other players on the plant scene. Here it is growing up a tree,

and sprawling over another invasive, garlic mustard.

Even those thistles with their prickly personalities aren't off-putting for a Mile-a-Minute vine.

It's said to have been an accidental introduction from eastern Asia via the nursery trade, originally gaining a foothold in York County, PA, in the 1930s and spreading from there.

Rampancy rules in this photo, as mile-a-minute swarms an autumn olive--a highly invasive shrub. When mile-a-minute's around, the curtain doesn't fall on other plants, but rises, in a wave of triangular leaves.

Here's Mile-a-Minute chasing the growth tip of a blackberry. Check back in a month to see who won the race.

Here, a privet's growing a prickly skirt.

Those pink flowers are Canada thistle, invader of many a garden bed, which is about to meet its match.

Long-time ubiquitous invasives, multiflora rose and Japanese honeysuckle, are joined by Mile-a-Minute.

You'd think perennial vines like wild grape would have a big advantage over an annual vine that has to spring anew from the soil every year, but Mile-a-Minute is looking up to the challenge.

Note the holes in the Mile-a-Minute leaves. Those are most likely from a weevil that was introduced as a biological control. The hope is that the weevil will become numerous enough, and consume enough triangular leaves to slow the wave of Mile-a-Minute engulfing the countryside.

Thus far, the Mile-a-Minute looks undeterred, growing over the slowly maturing fruits of wineberry,

and the pale stems of native black raspberry.

Beyond any ecological impact of such rampancy, it's interesting to reflect on the aesthetic and emotional impact of seeing a landscape being overrun by Mile-a-Minute. A healthy native prairie, for example, teaming with many species of grasses and wildflowers, all reaching for the sun with no inclination to crawl over one another, gives a feeling of striving, freedom, diversity, peaceful cohabitation, tolerance of one species for another. In contrast, a vine like Mile-a-Minute creates a smothering effect, a sense of clutter and thorny entanglement, a suppression of difference, an oppressive dependency that plays out as a punishment for any plant that dare reach a sturdy stem for the sky.