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Answer Man: What happened to the weeds by Silver Lake?

August 9, 2018

Dear Answer Man, could you explain how the decision was made to kill the beautiful native species planted along the southwest bank of Silver Lake. I remember reading a column in the Post Bulletin opining that the tall native plants were blocking the view of the lake. Now, after the area was sprayed, most of the shore line is dead, weedy and ugly. I’m curious who approved this and why? The rest of the lake shoreline is absolutely gorgeous right now. Thank you. — Sue

Sue, you’re not alone in noticing the sprayed patches along the shoreline. I’ve seen them too during my early morning strolls, where I’ve been known to draw a following of geese by force of sheer intellect.

First, you are correct in remembering a previous column mentioning the tall plants that used to grow along the shoreline. They were first mentioned in the June 2 Nature Nut column penned by Silver Lake fan Greg Munson. Munson’s complaint was that the tall plants blocked views of the lake.

As you and I have both noticed, at least some of those tall plants are now gone, although patches of tall grass and other wildflowers still flourish between the sprayed areas.

I went to Michael Nigbur, Parks and Forestry division head for the city of Rochester, to get the dirt on what happened.

According to Nibgur, those bare patches are the result of spraying from approximately two weeks ago to control problematic overgrowth of cup plant (also known as silphium perfoliatum), one of the native species originally seeded in the area as part of a shoreline buffer installed in 2007.

The buffer contained a mixture of native plants intended to help protect the soil of the shoreline and control geese populations, as well as filtering stormwater runoff into Silver Lake.

Unfortunately, someone’s elbow must have been jogged when they were mixing up the seeds for planting, because the cup plant got a little out of control.

Turns out the cup plant (much like the Answer Man) is a tough Minnesotan that always gets the best of the competition. That’s not a problem if you’re the Answer Man, but Nigbur says it caused issues in the shoreline buffer, where cup plants choked out other species.

Since part of the point of the buffer was to create a strip of diverse prairie habitat, the cup plants had to go. However (much like the Answer Man), it’s not easy to make them go if they don’t want to. Nigbur said the Park Division tried cutting, burning and weeding to control the plant’s growth, all “to no avail.”

Spraying seems to have done the trick, however, and now that they’ve killed off most of the cup plant, Nigbur says the plan is to turn over that soil and reseed with more native plants, sans cup plant. Additionally, he intends to conduct a wholesale review of the landscape around the lake to identify other potentially problematic species.

If things go according to plan, you should expect by next summer to see those bare, dead patches replaced with the tall grass and wildflowers that currently surround the east side of Silver Lake.

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