Tom's Blog

Saturday, July 30, 2016

Hedge parsley at Pleasant Valley Conservancy

We first found hedge parsley (Torilis japonica) at Pleasant Valley Conservancy over 20 years ago. At that time it was essentially unknown in Wisconsin and Kathie collected seeds from a small patch along Pleasant Valley Road, thinking it might be a good thing to plant. Fortunately, she first sent a sample to Kelly Kearns, the invasive plant specialist at the DNR, who informed her that it was an exotic, recently arrived from Illinois.

It's a rather unassuming looking plant, not nearly as destructive looking as wild parsnip or garlic mustard. Unfortunately, in many ways it is worse than those two. Like garlic mustard, it grows best in shaded sites, such as forest edges, although we have also found it in some of our savannas.

It is a biennial or winter annual, growing the first year as low, parsley-like rosettes. Like garlic mustard, the first-year plants stay green until late fall, even until snow fall. It could be sprayed at that time, but unfortunately its rather delicate leaves get covered up by tree leaves so that it is hard to find.

The seeds stick like velcro and are undoubtedly transferred by rodents and deer. These seeds stick a lot worse than those of garlic mustard.

Once I marked some first-year patches in late summer and then returned to them in early December, blowing the fallen leaves off with a leaf blower and then spraying with glyphosate. (This is an ideal time to spray, since all the native vegetation has senesced and hence not affected by the herbicide.) This technique worked, but unfortunately the first year plants are really hard to find among all the lush vegetation. So mostly we have relied on hand-pulling second-year flowering plants. If you get them early enough you can just lay them on the ground, but once they start setting seeds they have to be bagged (again, like garlic mustard).

We have been trying carefully to pull all flowering hedge parsley plants every year, ever since we first discovered this plant, but have been unsuccessful in eradicating it. Because of its delicate structure, it is hard to see in the woods, and only shows up well when present in large flowering patches.

This year hedge parsley is the worst we have ever found it. The shady North Woods has been especially bad, and our crew has been working there 2-3 days a week for the past 2-3 weeks.
The results of a 15 minute "pull" by two people in a shady roadside near PVC.

Since we started controlling hedge parsely 20 years ago, it has become lots more frequent on roadsides in our area. Again, it is lots more difficult to spot than garlic mustard or wild parsnip, so it can easily be missed when driving along at 50 mph. I suspect the distribution map shown below needs a serious update, as it is easy to miss this species. Lots of land managers may be unaware that they even have it. Because of its transmittal by very mobile animals like deer, it can get inoculated quite far from roads. I have seen it deep along old abandoned woods roads that are undoubtedly still used by deer.

I have little hope of eradicating hedge parsley from PVC, but we are committed to doing the best we can. We usually budget two weeks in mid- to late-July, just after the sweet clover season is over.

Fortunately, because of its preference for shady areas, it is less likely to show up in prairies, except along edges near woods.


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