Invasive plants and the herbicide leaf spritz

I use the term "spritz" to indicate a brief squirt of an herbicide on a plant leaf. The herbicide I am using is the oil-soluble form of triclopyr (Garlon or Element 4) diluted in Bark Oil (at a 15-20% concentration). This is a new technique for me, and I have found it to be very effective in "killing" woody or nonwoody invasive plants. This post describes its use for control of small buckthorn seedlings, the usual growth form arising from the seed bank, and for Canada goldenrod, a persistent rhizomatous invader.

I think this technique has wide application in restoration work, but I have only tested so far it in a few cases. However, it appears so useful that I hope others will test it also.

The photos here show what happened to buckthorn stems five days after only "two" leaves were spritzed with herbicide. There was no attempt to completely cover the sprayed leaves. Rather, a single spritz from a small spray bottle was directed at each leaf.

The original intent had been to use the basal bark technique on these small stems. However, this time of year, when there is so much living plant biomass on the ground, it is difficult to expose bare stems for the basal bark treatment. Instead, I just spritzed a couple of leaves. Note that even the leaves that were not spritzed were affected. In fact, the whole plant is killed.

This technique is easy to use. Our crew has been working in very leafy bur oak savannas where almost all of the plants were "good", with occasional buckthorn seedlings. It takes a second to spritz two leaves. Since most buckthorn seedlings are multi-sprouted, it takes about 10 seconds to spritz two leaves on each stem. The buckthorn plants are easy to spot, since the leaves have a characteristic dark-green lustre. The stems of most buckthorn plants are erect and the leaves are clear of any "good" plants. Spritzing is just a one-handed operation. Although I have been spritzing two leaves, only one may be necessary.

The leaf-spritz technique also works well for nonwoody plants. I have used it extensively for woodland sunflower, and have been testing it for Canada goldenrod. Again, spritzing a couple of leaves of each stem is all that it takes. The photo here shows a small Canada goldenrod clone that was spritzed about two weeks ago. Again, just two leaves were treated. The stems that were not treated were unaffected. Note also that the Rudbeckia hirta stems adjacent are not affected. It is very easy to spritz a leaf without getting herbicide on nontarget plants.

We use simple spray bottles that one can purchase at any hardware store, in 16 and 32 ounce sizes. Because so little herbicide is needed, the 16 ounce size works well. I carry the bottle in a pouch bag fastened to my belt. These bags are sold for carpenters to carry power drills, but they work fine for spray bottles. With the spray bottle at the waist, it is always ready when a new target plant is found.