Tom's Blog

Wednesday, November 26, 2008

Sumac control now under way

Sumac is one of those native species that can become a major problem in prairie and savanna restoration. Some folks simply let it exist, which is a mistake. It is fiercely clonal and has the potential to dominate a site, given time. Annual burns will set it back but do not eliminate it.

Stop and look at some of the sumac clones along the highways of southern Wisconsin. Because of the heavy shade they create, the ground underneath is essentially sterile.

At the last North American Prairie Conference in Winona there was a paper on eradicating sumac in a Nebraska prairie. According to the author, over the years that prairie had become about 50% sumac!

For some years, we tried to get rid of sumac by simple mowing, generally in mid summer. This sets it back, but does not get rid of it. A large clone that Kathie mowed at Black Earth Rettenmund Prairie was greatly set back for a year or two but has now returned, just as bad as ever. Obviously, there are living rhizomes underground that eventually grow and recolonize the site.

One of the problems with sumac is that it has such stunning fall color! This year was especially good, and many people remarked at how beautiful it was. This was true, but from my perspective, the fall color was an opportunity for us to set up a sumac database so that we could eradicate it in the winter. Every sumac clone was located with GPS, and was given an ID #. Single plants were ignored and only the clones were marked. We ended up with over 100 clones, which seems like quite a few to me!

How to eradicate? The researcher at the Prairie Conference used foliar triclopyr, applying it by a sponge device from the back of a tractor. However, our topography does not permit use of a tractor.

After returning from the Prairie Conference, I set up some experiments using triclopyr as a basal bark (Garlon 4 in oil). At that time, all of the sumac clones still had leaves, so it was easy to monitor the results. I did about 25 small clones, spraying about a 10 inch band at the base of each living stem. Within a week the leaves were looking wilted and within two weeks the leaves were all brown. If was after this success that we set up our sumac database.

We started our basal bark work on the clones a few days ago. All the leaves are gone from the clones, making them easy to get into. According to the Dow Agrosciences recommendations, if the stems are less than one inch in diameter you only have to spray one side. It is going to take quite a bit of herbicide, but the expensive part is not the herbicide but the wages of workers. Hopefully, we will only have to do this work once every ten years.

We are keeping track of which clones have been sprayed, so that it will be possible for us to know we have done them all. Also, we can return next year and look for any problem areas.

Winter is a good time to do basal bark treatment. Even if the temperature is below freezing, the herbicide in oil remains liquid. However, we do need snow-free ground. Hopefully, this year won't be as snowy as last winter!

1 Comments:

Blogger savannagain said...

If sumac is native, why is there such a huge effort to eradicate it as if it didn't originally exist in the savanna ecosystems naturally? There seems to be a big effort at Pleasant Valley Conservancy to eradicate native shrubs, whether it be hazelnut, gray dogwood, sumac or whatever. Why is this? Is it because these shrubs wouldn't have existed in these types of ecosystems without the advent of european settlement? Like the upland colonization of red maple?? If these shrubs are native, wouldn't prescribed burning be the only dictator of what would have naturally grown on these sites?? I don't understand the strategy behind removing native shrubs.

November 26, 2008 at 6:11 PM  

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