Hairy bittercress worst weed of early spring

I just read an article that likens hairy bittercress (HB) to the “cranky old man up the street.”

If you are familiar with hairy bittercress, you will most likely agree. If you are just now learning about that pretty little thing that seems to be everywhere, you will probably soon agree.

I was recently describing what this weed is to my sister and she said it should be called Satan. Maybe that’s a little harsh but this weed is definitely a nightmare.

Let’s look more closely at hairy bittercress.

It is a winter annual broadleaf weed that is a member of the mustard family (Brassicacaea). It was labeled the Weed of the Week back in 2018 by The Ohio State University’s “Buckeye Yard & Garden onLine,” not because it is popular, but because it is prolific.

The genus name of HB is Cardamine (Greek for “Kardamon,” meaning “cress”). The species name is hirsuta, which is Latin, meaning “hairy.” Hirsuta refers to the tiny hairs found on the leaves and stems.

North Carolina State University lists hairy bittercress as being native to Europe and Asia, a weed that has been introduced to most all other continents.

It appears as a small, low-growing weed that has two to four pairs of round or kidney-shaped leaflets on each leaf stem. The 3- to 9-inch flower stem emerges from the center and produces small flowers, each having four white petals that form a cross-like shape.

The fruit of hairy bittercress appears from March through May. The long, narrow seed pods (siliquas) stand upright around the flower and disperse seeds at maturity. Each pod can contain up to 30 seeds that can “burst” up to 16 feet from the HB weed.

Pennsylvania State University Extension states that botanists call the mechanism “ballochorym,” meaning ballistic seed dispersal. Each plant is capable of producing 600 to 1,000 seeds, according to NC State.

The best way to control hairy bittercress is prevention.

Hand weeding is not difficult because the fibrous roots are usually shallow. However, with our mild winter and frequent rainfall, HB is abundant. They need to be removed before maturity because any slight disturbance (wind, rain, touch, etc.) will cause the mature capsules to pop explosively. Therefore, removing all of them can be very difficult, if not impossible.

Frequent mowing in the spring removes the flowers before the seeds develop. If hand removal or mowing is used, do not compost, but dispose of all clippings, because the flowers will develop seeds. If composted, the compost will serve as a hairy bittercress incubator.

A pre-emergence herbicide used in late summer will help prevent successful emergence. If HB has already developed, the use of a post-emergence applied to the plants that are growing actively before the seed pods form may be effective. Organic options are available.

It is very important to read and follow all instructions on the herbicide, not only to increase effectiveness but also to prevent personal or environmental harm.

And a surprise — the flowers and leaves of hairy bittercress are actually edible.

They are not bitter as the name suggests, but have a mild peppery taste. I have never tried them nor do I know anyone who has, but in my research, it is suggested to add a few springs to salads, salsas and pesto.

For more information, http://go.osu.edu/bittercress

Dolak is an Ohio State University Extension Master Gardener Volunteer in Mahoning County.


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