Tom's Blog

Wednesday, August 31, 2011

Canada goldenrod control

Two weeks ago I mentioned a technique we had developed for controlling Canada goldenrod. This invasive native is often a problem in prairie restoration. Since it is clonal, it often forms fairly large patches, and grows so densely that other "good" species can't get a foothold.

As I wrote, most of our Canada goldenrod patches are primarily along the edges of the prairies, and hence are relatively small. The leaf spritz technique we use is ideal under these conditions, since it permits very selective treatment of the goldenrod without affecting adjacent plants that are even fairly close.

We use a 20% mixture of triclopyr (Garlon 4) in bark oil, dispensed with a hand-held spray bottle. A few leaves on the upper part of each stem in the clone are given a brief "spritz". The few leaves spritzed are high enough on the stem so that no stooping is needed.

The photos here show what a plant that was in full flower bud looks like after about 2 weeks. The adjacent untreated plants are completely unaffected.

I admit that this is a relatively slow technique, since one has to deal with each stem individually. However, this has the advantage that nearby good plants are unaffected. Marci and I were able to treat about a dozen reasonably large clones (15-30 stems each) in less than an hour.

As in most invasive plant control, the best time to initiate attack is when the problem is still small. Now is a very good time to do this, since Canada goldenrod is in flower and hence easy to find.

If all the stems in a clone are treated, you get rid of the clone for good. Last year when I first used this technique, I marked some treated clones and found no new growth this year.


Blogger Chris Z. said...

Have you tried a lower % triclopyr for your treatment. I'm just curious as 20% seems rather high, since we are having success killing buckthorn resprouts in a 2% triclopyr/water solution?

September 6, 2011 at 7:08 AM  

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