Never Judge a Book by Its Cover: Flowering Rush

Flowering Rush (Butomus umbellatus) -- just because it's pretty doesn't mean we have to like looking at it
(fortunately, the seen above is not on Standing Rush property; but it's close by,
and we're doing our best to avoid a full-fledged invasion)

One of my new year's resolutions is to take the time to circle back into last year's field season to tell stories that I couldn't find the time to tell when the sun rises early and sets late. On a cloudy, balmy January afternoon seated in my office chair, where the quiet is only interrupted at present by the nearly constant ping of incoming email and texts and the distant rumble of seasonally misplaced thunderstorms (currently rolling over the marsh), it seems appropriate to share some summer green.

Clusters of a dozen or more flowers -- each about an inch
across and suspended from an umbrella-like network
of stems -- introduce both vibrant color
and the risk of an unwanted invasion

And in this case, I can also share some pinks, yellows, and lavenders. Flowering Rush (FR) -- NOT to be confused with Standing Rush -- is another of our region's visually impressive but ecologically depressing invasive species. With origins in Africa, Asia, and Eurasia, its range is vast, and based on what we've observed in the last several years, we can see why.

When we began our field work in 2015, Flowering Rush (or "F-ing Rush," as some prefer to affectionately refer to it) seemed very limited, at least in our corner of Sandusky Bay. We can remember isolated plants in a ditch area that fluctuated from inundated to dry multiple times throughout that first season.

But as water levels have continued to rise and hold, not just locally but across the Bay, Lake Erie, and all of the Great Lakes, we've seen what seems to be a sustained proliferation of the glossy-leaved plant all around us -- and unfortunately, to some extent, within our marshes' boundaries.

While the surface area impacted remained relatively modest in 2018 (under a single percent of our overall area), Flower Rush eradication became Job #1 for Roy last June - August. Many a hot day was spent scouting and spraying. Unfortunately, mechanical control (e.g., cutting or pulling) only amplifies the problem thanks to scores of stubborn "bulbils," or bulb-like propagules that grow within the root structure. A backpack sprayer (equipped with a cocktail of glyphosate, imasapyr, and a surfactant ) did the job for individual plants and small, isolated pockets that typically hugged dikes and canals. But on a few occasions, we actually tag-teamed to carefully apply herbicide both by backpack and by boat (equipped with a battery-powered ATV sprayer tank).

Roy on Flowering Rush patrol; identification was relatively easy as our eyes got trained to the showy, pink inflorescence --
but the challenge is FR tends to come on strongest from mid-late summer and blooming is a staggered event;
plus, the invasive seems quite at home among our desirable cornerstone emergents: cattail and soft-stemmed bulrush

Isolated plants (especially with flowers) became easy to identify and spray, but it seemed to take two discrete spray
events, separated by at least a week or two, to achieve the desired result

An example of what a FR looked like when it was ready for its second spray; two weeks later very little vegetation
remained, at least above the water surface

At first blush, this stand of largely soft-stemmed bulrush (a desirable emergent species thanks to its food and shelter
contributions) does not look too bad; but click to enlarge to see all of the pink flowers of FR circled in red

An off-site location heavily infested with FR; the risk is that, much like Phragmites, Flowering Rush will become a complete monoculture -- monopolizing the unique setting without supporting much other plant or wildlife diversity to speak of

We have heard horror stories of Flowering Rush growing from depths of up to nine feet of water and in monocultures so thick and persistent that impacted areas -- sometimes hundreds of acres in size -- are virtually impenetrable. But we are seeing decent evidence that FR doesn't respond well to turbid water (a condition we can encourage, as needed) and that we have a herbicide technique that should be effective. So for now, we feel fairly optimistic that we are staying on top of the onslaught. It's another chapter in the invasive species saga.