Olive Invasion

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Autumn Olive, a.k.a. Russian Olive, is the classic invasive, and one we have had to deal with on our new country property. It was first cultivated in Germany and imported to the U.S. in the late 1800s as an ornamental plant, where it has spread to nearly all of the central and western states. At first glance, it is an attractive bush or small tree with characteristic bladelike silver-backed leaves. In the spring it blooms with bright yellow flowers which are replaced by silvery-yellow berries.

Birds love the berries; it is browsed by deer and barked by rabbits. The berries are tart but edible, and some people make jelly or even wine out of them. This apparent attractiveness is part of what makes it a problem. It spreads from birds distributing the seeds, and through its root system. And uncontrolled, it will grow almost anywhere, and will out-compete almost anything in its path.  I have seen it grow up and choke out even well-established pines in a forest where the soil is so acidic almost nothing will grow. Once you begin to recognize it, you will see it everywhere.

Because it is spread by bird droppings, it can spring up almost anywhere, even where it has been recently eradicated. One plant is all it takes to get going, so annual inspections are needed to make sure it doesn’t re-establish itself. But if you cut it down, it grows lusher than before, and if you pull it out, any remaining root fragments will send up more shoots in the spring. So how do you rid yourself of this stuff?

I did a lot of research trying to determine the most effective treatment for a very large and well established stand of this attractive nuisance. Although I realize that some people eschew the use of herbicides, there seems to be no other current solution to dealing with this problem. Obviously, all recommended safety precautions should be followed when using these chemicals, and you should always follow the manufacturer’s instructions. So far, the program has proven to be very successful in eradicating the problem with no regrowth.

The program involves a multi-step approach. The first step is n the spring when the plants are actively growing, using a strong basal bark application of a triclopyr-based herbicide such as Garlon, Release or Brush-B-Gone. The benefit of this foliar herbicide is that it leaves grasses and conifer unaffected. We used a 20% solution of Garlon 4, soaking about 1 inch of each plant all the way around the base. There was no special preparation- we sprayed it right on the bark. This was highly effective against even well-established plants. On the smaller sprouts, the entire leaf system was covered.

The second step is in the early fall, after the heat of summer has abated somewhat and the plant is not growing. Cut the plants off at the base, and immediately daub the cut stump with a full-strength application of a glyphosate herbicide such as Rodeo, Roundup, or Tumblweed. Since this is a non-selective herbicide, it will kill anything it touches so extreme care should be taken with the application.

After this, it’s best to revisit the area every spring to check for sprouts, and pull them out or treat them again with triclopyr. This approach is very aggressive, and may be impractical or cost prohibitive in very large applications, but it has worked well for us. If anyone else has had success with another less aggressive approach or one is less reliant on herbicides, I’d love to hear about it.