Late fall control of hedge parsley

Hedge parsley (Torilis japonica) is a newly "emerging" invasive plant that has recently become of considerable concern. In a sense, we at Pleasant Valley Conservancy have been one of the "pioneers" in hedge parsley control, since we have been controlling it for almost 10 years.

Many people have not been aware of the widespread distribution of hedge parsley in southern Wisconsin. The U.W. Madison Herbarium shows it present in just a few counties in the state (including Dane County). The first Dane County collection in the Herbarium archives was made by Olive Thomson in 1982, and her husband John made more collections later. Kathie deposited the first collection from Pleasant Valley Conservancy in 2004. Here is a link to the Herbarium web site.

Because it has only recently become known, many landowners do not know they have it. I have seen it in large infestations in several sites in southern Wisconsin.

It is a relatively inconspicuous member of the carrot family, and only when it is flowering is it easy to spot in a natural area. Its preferred habitat is shady wooded areas (fairly similar to garlic mustard). It is what is called a "winter annual". It sets seed in late summer, and the seeds germinate in the same fall, forming first-year plants that overwinter. The seeds are very sticky (much more so than those of garlic mustard) and are presumably transported by animals.

Our preferred method of control of hedge parsley is by handpulling in mid summer, when it is in flower. However, like garlic mustard it can also be controlled by spraying in late fall, when the new plants are still green. Yesterday Susan, Marci, and Amanda spent the afternoon spraying (with glyphosate) on our ridge top, in areas that we knew from previous work were infested.

Unfortunately, spraying hedge parsley in wooded areas is difficult, because the plants are often covered with leaves, so that herbicide coverage is often spotty. However, there were plenty of lush green leaves visible. Glyphosate is the herbicide of choice because this time of year all the native plants have senesced, and because glyphosate has no soil-residual, it has no effect on these natives.