Tom's Blog

Monday, October 6, 2008

Good time for foliar spraying of small buckthorn

Getting rid of large buckthorns is the easy part (really!). But the ferocious seed bank means that small buckthorns will keep coming for (who knows how many) years. These small ones can be handled by the laborious work of cutting with a handclipper and treating every cut stem with herbicide (triclopyr, Garlon). But even a small patch handled that way will take hours, and lots of stoop labor. Also, the small ones are fairly hard to find mixed in with all the other herbage.

But right now, and for perhaps a week at most, these small buckthorn shoots can be easily seen, making foliar spraying possible. Most of the native vegetation is dying back and the leaves are turning yellow or brown, but the buckthorn leaves remain green and can be easily seen. I assume the leaves remain green because this exotic invader remains adapted to the European or Asian environment where it came from, which has a longer growing season.

We did some foliar spraying last fall, but got started a little late and the buckthorns were already losing some leaves. This year I determined to get them earlier, and have been monitoring several egregious infestations. Today I sprayed a couple of major patches in the bur oak savanna. What would have taken hours I was able to handle in minutes.

As the photos show, these buckthorn stems are fairly short, and quite leafy, making it possible to spray them without spraying good plants. Even if a few good plants are hit, triclopyr only affects broadleaved plants, so that grasses, such as the savanna ryes and brome, will not be affected.

The top photo shows one of our Solo backpack sprayers with the special custom straps that make it possible to work all day long without getting too tired. This harness is a little expensive (from Forestry Suppliers) but is worth it.

For several years I have been monitoring carefully the locations of our buckthorn infestations, and concluded that they are primarily in areas with an underlying dolomitic rock base. At Pleasant Valley Conservancy dolomite is mostly restricted to the top of the ridge. Off the ridge top, the bedrock is sandstone, and buckthorn is almost absent (honeysuckle instead). A review of the European ecology literature uncovered a very detailed paper on the distribution of buckthorn in England. It turns out that it is restricted to carbonate rock areas there also. In fact, the English consider buckthorn to be a "calciphile".

Since our dolomitic areas are fairly small, I am encouraged that we will eventually be able to bring buckthorn under control. Unfortunately, it took us too many years to realize how bad the seed bank was, and as the photos show, we have some fairly significant infestations.


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