Tom's Blog

Wednesday, October 14, 2009

Further on sumac control

I am now convinced that we can control sumac with Garlon 4 basal bark (no cutting), provided we return to each clone several times during the summer to spray resprouts. In order to ensure that we don't miss a clone (either in the initial treatment or for follow-ups), we have set up a sumac database, marking each clone with a numbered stake. The location of each stake is recorded with our Garmin GPS, and the whole database uploaded to ArcGIS so that each clone can be mapped. (The map below is a low-resolution version that will upload quickly. I'd be happy to send a high-resolution version to anyone interested.)

Here are the gritty details of how we did this: We made 5 foot wooden stakes out of 1 X 2 wood strips (furring strips) and used a Dremel vibrating marking tool to mark each stake with a unique number. The sumac clones are now showing their brilliant red fall colors and are hence easy to spot. We put a numbered stake at each clone and recorded its GPS coordinates. A few notes were made about the size of the clone, and the management unit it was in. Since this is the second year of our sumac control program, there were fewer clones (32 total; last year we had over 70).

The Garmin data were uploaded to my computer and converted into an ESRI shape file which displays in ArcGIS. Each red dot on the air photo below is a single clone.

Once our fall work is finished (seed collecting, burns, planting), through the winter, when weather conditions permit, we will be basal barking the sumac clones. Then we will return to each clone in June 2010 and again in late August to treat all the resprouts. Hopefully, that should eradicate the clones, but we will make sure by returning in the summer of 2011. The value of having permanent markers and the map is that we can be sure we don't miss any clones. The print out of the Excel file is used as a checklist.

There is one more part of the sumac control routine. This is to basal bark any single sumac plants during the summer of 2010. These single plants represent the sumac clones of the future, so by killing them now we can keep them from getting established. We spent quite a bit of time this summer on these singles or small groups, and this work was successful. We don't need each such plant in the database, since the Garlon treatment kills the whole plant.

I said above that we were not doing any cutting. This is because our clones are relatively small, fewer than 200 stems each. With very large clones, such as are often present in areas that have not been burned frequently, basal barking is fairly difficult because of the high stem density. In these cases, the best approach is to cut the whole clone with a brush cutter, carry away the mass of stems, and then treat each cut stem with Garlon 4 in oil, being certain that both the cut surface and the sides of the stem are treated (as in a basal bark). However, you still must return several times in the summer (and perhaps the following year) and treat the inevitable resprouts!

Anyone interested in background on the biology of sumac might be interested in the summary I recently posted on my web site.


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