CROOKSTON, MINNESOTA — Research is underway at the University of Minnesota Crookston to determine if goats are a good way to control buckthorn, an invasive weed.

Professors Leslie Lekatz and Matt Simmons, who teach in the UMC Agriculture and Natural Resources Department, have teamed up on a research project that is studying whether buckthorn seeds remain viable after they’ve passed through the digestive system of goats.

Buckthorn, which is native to Asia and Europe, was introduced into the United States in the 1880s as an ornamental plant used for hedge rows. The tree, which can grow 20- to 30-feet high and have a trunk circumference of 10 inches, produces abundant fruit in the form of berries. Birds carry the berries, which contain seeds that are distributed when the bird defecates.

The prolific plant is on the Minnesota Department of Agriculture list of restricted noxious weeds.

Restricted noxious weeds are plants that are widely distributed across the state and are detrimental to human or animal health, the environment, public roads, crops livestock and other property, but only can be feasibly be controlled by prohibiting the importation, sale and transportation of the propagating parts except as allowed by specific Minnesota statutes, according to the Minnesota Department of Agriculture.

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Birds eat buckthorn berries like these in this picture taken Oct. 28,2021. After the berries pass through the bird, the seeds germinate where they have been dropped.
Ann Bailey / Agweek
Birds eat buckthorn berries like these in this picture taken Oct. 28,2021. After the berries pass through the bird, the seeds germinate where they have been dropped. Ann Bailey / Agweek

Buckthorn also has spread across North Dakota, South Dakota and Montana.

In Montana, buckthorn has been reported in at least 27 counties, according to Montana State University Extension. In 2017, the plant was placed on the state’s noxious weed list as 2A species, which means that it is common in isolated areas of Montana.

Buckthorn control is difficult because it does not respond to multiple control methods.

Students enrolled in the UMC Natural Resources program unsuccessfully have trimmed buckthorn in the Red River Valley Natural History Area near the campus, and then applied herbicide to the plant stumps, but the invasive weed continued to spread, Simmons said.

“It’s very robust, very competitive,” Simmons said.

Besides choking out native underbrush in forested areas, buckthorn infestations can result in damage to soybean crops. Soybean aphids overwinter in buckthorn, which is a common shrub in shelterbelts in the northern United States, and fields near to their location often are the first to be colonized by aphids in the spring, according to South Dakota State University.

Six Boer goats at University of Minnesota Crookston are being used for the ongoing buckthorn control research project, which first involved letting the goats eat buckthorn in the Red River Valley Natural History Area near the campus for two weeks in the fall of 2020. The goats were again penned in the area in late spring and late summer 2021.

The research was conducted during different time periods to determine at what time of year the goats’ control of the buckthorn is greater. Besides determining how many buckthorn seeds are digested by the goats and whether the ones that don’t are viable after passing through the animals, researchers are studying whether the animals can control small buckthorn plants by eating them.

Buckthorn leaves, like these in this photo, taken Oct. 28, 2021, remain green after other leaves have turned color or fallen.
Ann Bailey / Agweek
Buckthorn leaves, like these in this photo, taken Oct. 28, 2021, remain green after other leaves have turned color or fallen. Ann Bailey / Agweek

A year ago, after the trials in which the goats ate buckthorn plants and berries in the Red River Valley Natural History Area, researchers hand-fed each of the six goats, which were penned in the UMC livestock barn. The goats were individually fed 750 berries that contained three seeds each. During the two-week feeding study, the feces was collected every 12 hours, and the seeds were extracted.

Only 25 of the total 2,250 seeds that were recovered in the feces were viable in the 2020 hand-feeding study, Simmons said.

The UMC researchers repeated the project in 2021 during the last week in October and the first week in November.

Once all of the seeds have been recovered from the goat feces, the researchers will plant them to see if they germinate. The latter part of the project wasn’t completed in 2020 because there weren’t enough seeds recovered.

“This year, we tweaked our collection process, and we are getting more than last year,” Lekatz said.

There is not enough research data yet available to speculate about whether the goats are an effective buckthorn control method, she said.

However, the research itself is valuable to the undergraduate students involved with the project and is an opportunity most universities are unable to offer, she said. Meanwhile, the student researchers, who include some who are majoring in agriculture, and others in natural resources, are working together on a project, similar to what they likely will do in their future careers.

“It seems like a perfect synergy,” Lekatz said.