Brush control at Black Earth Rettenmund Prairie

Although Black Earth Rettenmund Prairie is one of the finest prairie remnants in southern Wisconsin, it still suffers from the legacy of past degradation. When restoration was first started in 1986, the site was about half wooded (per my GIS analysis of air photos), and most of the areas that were woody then still provide challenges for restoration.

Last Saturday our monthly work party at Rettenmund concentrated on brush control at the knoll on the north unit. In 1986 this was a large clone of aspen. Although all the trees were removed, this area has been one of the most difficult to get restored. The photo here shows what the top of this knoll looked like on Saturday morning.

What brush was present?

• Scattered aspen shoots
• Large amounts of prairie willow
• Numerous large clones of hazel
• Scattered small honeysuckles
• Rare buckthorn

We are using Garlon 4 in bark oil as a basal bark treatment for all these woody invaders. We either use a hand spray bottle directly, or use sponge applicators loaded with herbicide. Some people fastened the sponge applicators to long rods so that they did not have to stoop. Others used a hand-held sponge. In both cases, the herbicide was loaded on to the sponge with a spray bottle.

For the sort of habitat shown in the photo, the basal bark approach is ideal. Especially this time of year, when all sorts of "good" species are coming up. Some of the species we saw in flower:

• Seneca snakeroot
• Yellow star grass
• Shooting star
• Hoary puccoon
• Bird's foot violet
• Blue-eyed grass (except it is white at this site)
• Wood betony

By using the sponge (or a hand spray bottle), you can deftly apply herbicide to a woody stem without harming a nearby prairie plant. Admittedly, this is stoop labor, but at a high quality site such as this, you can't use a backpack sprayer.

One of the surprises was the large amount of spreading hazel (Corylus americana) clones. We had seen an occasional hazel bush at this site, but had never seen rhizomatous clones. In fact, many people doubt that hazel is rhizomatous, despite the fact that there are published papers that demonstrate this. Where had these clones come from, and why, for the first time, are we seeing them on the top of the knoll? I counted over 350 separate stems in one clone that I treated. Obviously, we will have to keep on top of this new invader.

Hazel clone at Black Earth Rettenmund Prairie