Story of a small buckthorn area

We've been working for over 10 years to eradicate buckthorn in some of our savanna areas. It is hard now to realize how dense the buckthorn was when we started. Generally, you could not see past the first line of buckthorn plants into the interior of a unit. Knocking the buckthorn back, by basal bark and cut-and-treat, got rid of these large thickets, but due to seed bank and presence of dormant root masses, there was plenty of new growth. How to eradicate permanently?

This is the story of a single area where I am now convinced that I have successfully eradicated buckthorn. The area is Unit 19A, a long, narrow unit on top of the dolomite, where buckthorn had been well established. In the winter of 1998 the buckthorn had been basal barked (Garlon 4), which effectively killed the large stems. In the spring of 1999 no shoots came up next to the treated stems.

However, during the summer small shoots sprang up throughout the unit. They were effectively killed (1999 or 2000) by basal bark treatment, using a sponge-type applicator.

Unfortunately, by this time our attention had been turned to complete clearing of the south-facing slope and the ridge-top savannas, so this area was neglected (overlooked).

By 2006 the buckthorn was back in full force, and I decided to use this as a test area, small enough to deal with, but large enough so that there was plenty of buckthorn.

In early August 2006 the whole buckthorn area was removed using a Stihl brush cutter. All cut stems were removed, and any stems missed with the Stihl were hand cut. Because the density was so high, the cut stems were not treated with herbicide. Rather, the cut plants were allowed to resprout, which they did with a vengeance.

Then in late Sept 2006 these resprouts were foliar sprayed, using fosamine (Krenite; a woody plant herbicide). (One patch was left unsprayed as a control.) At the time of spraying, the buckthorn resprouts were about 6-12 inches tall.

Observations showed that these resprouts were NOT from underground root masses. Rather, each resprout was from the first lateral bud below the cut stem. (See photo to left) Thus, cutting each stem eliminated apical dominance, permitting lateral buds to become activated.











At the time of spraying, the buckthorn stem density was about 75 sprouts were square meter! (See photo below.)

Observations made the following late summer of 2007 showed that the foliar spraying had greatly delayed buckthorn growth but had not eliminated it. Lots of shoots 2-4 feet tall. There was, however, lots of native vegetation becoming established, including zig zag goldenrod, arrow-leaf aster, purple Joe Pye weed, bottle brush grass, and white snakeroot. (The buckthorn control area that had not be sprayed in 2006 was then treated with Garlon 3A (foliar).

At this point, the very dense buckthorn patch had been eliminated, although there were scattered viable buckthorn stems throughout the unit. For the next two years (2008 and 2009), these stems were sprayed with foliar Garlon 3A in early October, at a time when most native vegetation had senesced. Then in mid-summer 2010 all remaining viable buckthorn stems were treated with Garlon 4 basal bark, using the sponge stick technique. Since by this time, viable buckthorn stems were quite scattered, the sponge technique was quite easy to carry out. Observations a few weeks after treatment showed that all treated buckthorn stems had died.

During the three years that the remaining buckthorn plants were being eliminated, the native vegetation was proliferating. Presumably because the buckthorn stem density was low, buckthorn allelopathy was not being exhibited.

Last November, Unit 19A was burned when we burned the north woods. Since no viable buckthorn stems were visible, the burn may not have had any effect on the buckthorn, but it probably greatly stimulated the growth of native vegetation this spring.

Returning to this area now, I was unable to find any living buckthorns, but very lush native vegetation. The whole Unit looks very good.

Because this unit is adjacent to the main trail along the ridge, it is very easy to monitor for buckthorn resurgence. We'll be keeping an eye on it, but I am very encouraged. This may be the first site at Pleasant Valley Conservancy where buckthorn has been definitvely eradicated. Lots of work, but worth it!

Interns starting to work

Kathie and I have been managing the Prairie Partners summer internship program for Madison Audubon Society for 4-5 years now. This year we have another nice group of college students whose long-term interest is in restoration ecology. The team rotates through five separate sites, and Pleasant Valley Conservancy's day is Tuesday. Amanda serves as their supervisor, and since she was an intern herself 3 years ago, she is well suited to the task.

After a morning of orientation to the Conservancy, the interns started work with a vengeance. The East Basin, our newest reconstructed prairie, is only in its second growing season, and still has lots of undesirables. They covered this whole 5 acre site, digging bull thistle, mullein, and garlic mustard (a small patch), among other things. Despite the bad guys, they found lots of desirable plants, including shooting star, lupine, spiderwort, prairie dock, lots of old-field thistle, and many more good prairie species. The burn we carried out on this "prairie" about 6 weeks ago probably helped get it started for the year.

Welcome, interns!

Pretty things at Black Earth Rettenmund Prairie

Yesterday Kathie and I spent some time at Black Earth Rettenmund Prairie. Right now all the early blooming species are up, and the views are spectacular. Well worth a visit.

We had great burns at the end of March. Late enough so that the snows were gone and the fine fuel was well cured, but early enough so that all living plants were still dormant. What a difference 6 weeks has made! Despite the cool spring, great early prairie plants.

The photo above (by Kathie) is of a typical area in the south burn unit. In addition to the orange hoary puccoon, there are loads of shooting star in full bloom, plus lots of blue-eyed grass, wood betony, pussy toes, Robin's fleabane, bird's foot violet, and yellow star grass.

The blue-eyed grass at Black Earth Rettenmund is interesting, since it is all white rather than blue. It is not uncommon to have both white and blue blue-eyed grass in the same area, and most people assume these are just variants. But we have searched extensively at Rettenmund and have never found any blue flowers.

Another point about the photo above: ten years ago when Kathie and I started managing this prairie, the area shown in the south unit had been heavily brushed in. Large honeysuckles especially, but also sumac, scattered buckthorn, and lots of other woodies. Most were eliminated by cutting and treating (Garlon), but last fall and early this spring crews made several passes through the whole prairie basal barking all remainng living woody vegetation. It is nice to see how well these areas have responded to careful herbicide use.

Of course, this prairie is just getting started for the growing season. Come back frequently!

Wood betony time

Wood betony (Pedicularis candensis) is an interesting species that is found in prairies and open wooded thickets throughout Wisconsin. Wood betony grows in hemiparasitic fashion upon the roots of grasses or other herbaceous plants. Because of its parasitic property it is able to exert considerable control on surrounding plants, and has hence been called a "keystone" species. (See Rich Henderson's paper on keystone species in the 18th North American Prairie Conference, available digitally through the U.W. Madison Digital Collections.) According to Henderson, there is a good probability that the presence of a keystone species such as wood betony will markedly enhance the diversity of a prairie or savanna site.

We had a few small native populations of wood betony at Pleasant Valley Conservancy, and have been working to extend these by spreading seeds.

This is the time of year when wood betony is very visible. It grows in patches and its light yellow color makes it easy to spot, even from a distance. Today we found it in a couple of our savanna areas as well as in two planted prairies, the Pocket Prairie and Toby's Prairie. The photos here, taken by Kathie, are from Toby's.

According to Henderson, wood betony particularly parasitizes grasses, and it is probably because of its reduction in prairie grasses that it increases diversity in prairie remnants. (The elimination of grass patches results in the presence of bare areas, where other prairie plants can become established.)

In planted prairies of extended age, large grass-free "holes" may be seen where wood betony has become well established.

If you can find a seed source (it is also available commercially) collect around the end of June. Throw seeds out in areas with heavy populations of grasses. Establishment may take some time, and the population will move around, since once it kills off its grass host it dies back, only to reappear in other grass areas.

The related species P. lanceolata, which is also common in our area, thrives in wet-mesic to wet areas, where we find it attacking clonal sedge species such as Carex trichocarpa.

Special savanna issue of Woodlands and Prairies

The magazine Woodlands and Prairies, published out of Monona, Iowa, is a very fine, full-color quarterly that focuses on restoration of midwest woodlands and prairies.

The new issue, just out, is a special issue on oak savannas. This particular issue is a follow-up to the Oak Savanna conference that was held in the Toledo, Ohio area in the summer of 2009. A lot of interesting information about the "Oak Openings" area of northwestern Ohio and southeastern Michigan is given. The following issue, due sometime in late summer, is also to be on savannas.

This magazine is highly recommended for midwest restorationists. Get more information at this link.



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Trillium recurvatum

Trillium recurvatum, a Special Concern species in Wisconsin, is now flowering in our front-yard perennial garden. (Photo by Kathie) We did not plant it, and have no idea how it got there. We also have some plants, not yet in flower, in the backyard. There is a good population of this species about a mile away from our house in Big Woods, one of the UW-Madison Lakeshore Preserve units, so it may have come from there, but not likely via us.

Interesting how plants, even rare ones, get around!


According to the Wisconsin State Herbarium web site, this plant is mostly confined to the southern tier of counties, and there is no collection for Dane County, where we live. Its main habitat in the state is southern Wisconsin upland forest (per Curtis).

We have never seen this species at Pleasant Valley Conservancy, where we have a big population of large-flowered Trillium (which should be in full bloom next weekend).

Early flowers (is it already May 1?)

It's not really news that spring is late this year. According to Wisconsin Ag reports, farmers have barely been able to get into their fields, whereas last year at this time, 20% of the fields had been planted.

I've been doing phenology for the past ten years and just reviewed my list. By this date in past years wood anemone, wild columbine, fringed puccoon, Jacob's ladder, and prairie violet would all be in flower. In some years, golden Alexanders would be in flower. Haven't seen any of these yet.

A brief survey today brought out only the following: Bloodroot (been out for a week or so); pussy toes; dooryard violet; early meadow rue; bird's foot violet (photo below); marsh marigold (photo above); and of course early buttercup, which has been up for almost two weeks. (Both photos by Kathie)

Well established plants with flower buds: Golden Alexander; large yellow lady slippers; shooting star; Jacob's ladder.

A brief survey indicates that this is going to be a great year for shooting star at Pleasant Valley Conservancy. Lots of savanna areas with remnant populations, and quite a few areas where we planted seeds 5-10 years ago are now finally producing good plants. This species takes quite a while to get established from seed.

Let's hope May will be better than April. (At least we got all our burns done!)