Invasive Olives


Some landscaping can just be too adaptable.  The genus Eleagnus is a good example.  They make beautiful accent shrubs with pleasant fall aroma.  The undersides of the leaves have a silvery color that almost dances in the wind.  Oblong fruits are sought after by songbirds and they are not bad table fare either, and good for you to boot.  They also tolerate drought well, so even a summer like this past one won’t faze them.

But here’s where the trouble starts.  The common thorny eleagnus or silverthorn, (Eleagnus pungens), is probably the least invasive of these, but it still grows like wildfire.  A large evergreen shrub, it thrives in the salt spray near the beach.

They flower in the fall and early winter and fruit matures in late spring.  These shrubs can be found in most nurseries and can be controlled by timely pruning.  Don’t let the fruits mature and birds won’t carry them off.

The Russian olive, (Eleagnus angustifolia), is a little more problematic.  Few nurseries around here carry it, but it can be ordered by mail.  Russian olive looks somewhat like the previous species, but leaves are only semi-evergreen.  It is super aggressive and will take over an abandoned field or pasture.  This one flowers in late spring and fruits mature in the fall.  Other than providing a fast growing screen the only good thing I can say about Russian olive is that the fruit is pretty good and can be eaten fresh or in preserves.

Autumn olive, (Eleagnus umbellata), looks very similar to Russian olive, but it even more winter hardy and more invasive.  Don’t ever be talked into planting this one.  You won’t control it.

Obviously the best method of controlling these species is to prevent them from becoming established. Plants should be removed as soon possible if they are found newly colonizing an area.

What can we do if they get a strong foothold?  We have two options.  The first is to attack them with bush hogs and herbicides.  Apply a 10 to 20 percent solution of glyphosate (Round-up) immediately to the cut stumps.  Foliar treatments are also somewhat effective for smaller patches.

If chemicals aren’t your thing you might have to live with some of it, but it’s not all bad.  The fruits are tasty and very high in lycopene, a strong antioxidant found in tomatoes.  Lycopene gives them their red color and has been linked to good prostate health.  Both Autumn olive and Russian olive are prolific, so you will have plenty of fruits to pick.  They have a rather large seed and it’s a trick to separate it from the flesh, but they’re not bad.  I consider these reddish drupes are a major wild food secret.

Fruits are best when eaten after a few frosts, much like wild persimmons.  They are somewhat astringent and sour before that but still edible.  They make an attractive reddish orange jelly with a smooth texture.  Flavor is similar to a cross between pomegranate and cranberry.  Make sure to add additional fruit pectin when making jelly, as natural levels are low.

Ted Manzer teaches agriculture at Northeastern High School.

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About tedmanzer

I grew up in Old Town Maine and got a B.S. at the University of Maine in Plant Sciences/ minor in Botany. From there I moved to West Virginia and earned a M.S. in Agronomy at WVU. I also met my wife there. She grew up in rural WV as the daughter of tenant farmers who raised cattle and hogs. Their lifestyle at times was one of subsistence and I learned a lot from them. I've always been a foraging buff, but combining my formal botanical knowledge with their practical 'Foxfire-type' background opened up my eyes a little more. I now teach agriculture to high school students at Northeastern High School in Elizabeth City, NC. My wife teaches with me and we make a great team. I also write a weekly nature/foraging column for the local paper (dailyadvance.com) and frequently publish articles in several other newspapers in northeastern North Carolina. I also have written several Christian nature/adventure novels that I plan to publish eventually. One is a five book family saga I call the 'Forgotten Virtues' series. In the first book, Never Alone, a young boy comes of age after his father dies in a plane crash, and he has to make it alone. Never Alone is now available in paperback, Kindle and Nook. The second book, Strange Courage, takes Carl from his High School graduation to his recovery from a nasty divorce. The third book, Second Chances, takes Carl from his ex-wife's death and the custody of his son to his heroic death at age 59. The fourth book, Promises Kept, depicts how his grandchildren react and adjust to his death. In the final book, Grandfather's Way, his youngest and most timid granddaughter emerges from the shadow of her overachieving family and accomplishes more in four months than most do in a lifetime. I use many foraging references with a lot of the plants I profile in these articles in those books.
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