Exploring The Last Green Valley: Autumn olive is silvery invader of field, pasture

Today, my focus turns to yet another invasive plant and one of the 10 most wanted in terms of problem plants in our region.

Our six acres of land in Putnam is mostly pastures and fields with trees predominately along the edges. When my wife first purchased the land, the fields had been left untended and had not been mowed for several years.

The result was fields covered with spreading brush and shrubs. The most dominate shrub was autumn olive.

Along with a good friend and the right type of equipment, she cut and mowed down the autumn olive, burned it in huge pile, and pulled up the smaller stems.

Since then, I have mowed or “brush hogged” the back fields at least twice a year and we’re pretty much autumn olive-free.

So what is autumn olive and why is it considered an invasive plant?

Autumn olive (Elaeagnus umbellate) grows as a shrub or small tree and was introduced to the United States in the 1800s. It was prized for pretty silver foliage, hardiness and bright red berries.

The shrubs were planted as an ornamental as well as for erosion control and windbreaks.

A close relative of autumn olive is Russian olive (Elaeagnus angustifolia) with a similar look and invasive characteristics but with orange berries.

While not found on my property, Russian olive is also prevalent in the country.

Unfortunately, both autumn and Russian olive have invaded open spaces, edge habitats and fields. If a hay field is left to return to nature, one of the first shrubs to move in is autumn olive.

That was our experience in our Putnam fields, and a drive through The Last Green Valley past old unused farm fields reveals a preponderance of autumn olive. Needless to say, it is alive and thriving here in The Last Green Valley.

Autumn and Russian olive are deciduous, woody species that grow from 6 to 20 feet as shrubs or small trees. Their multi-stems can create dense thickets. The twigs and branches appear silvery or golden and the stems appear speckled.

The leaves are oval or elliptic (similar to an olive leaf) with blunt points and are arranged alternately on the stem. The leaf edges are smooth and range in length from 2 to 4 inches and are 1.5 inches wide. The leaf is green to gray-green and smooth with the underside a silvery color.

The flowers appear in late April to May and are a white and light yellow color. They are fragrant and tubular with four-petaled flowers in clusters or individually.

The fruit is small and rounded with a single seed. In early summer the fruit is silvery and then it becomes juicy, ripening to a copper-speckled pink and red in the fall. The Russian olive fruit is orange colored.

The plant can be found in infertile soils due to its nitrogen-fixing ability. As a result it grows on forest edges, old fields, pasture, sand dunes and heavily disturbed areas. It does not do well in dense forest but will be found in gaps and along forest edges. It is rarely found in very wet soils.

Autumn and Russian olive are spread by birds and other wildlife that feed on the fruit. The plants grow rapidly and are able to bear fruit in just a few years. The shrubs are able to out-compete native plants and shade out shorter species.

Controlling the spread of autumn and Russian olive requires persistence and annual inspection and removal. Young seedlings can be pulled by hand (easier when the soil is moist). You’ll want to get all of the root system, and a weed wrench is a good tool for getting the roots.

Larger shrubs can be cut at ground level. The plants will regenerate from the stump so repeated cutting or application of herbicides such as glyphosate or triclopyr to the fresh-cut stump is suggested to prevent the plant from regenerating.

If you’re looking for a beneficial and flavorful use of autumn olive you may consider collecting the ripened fruit and making fruit leather similar to fruit roll-ups that are popular these days.

One of the more interesting books that I have picked up over the years is “Wild Plants I Have Known and Eaten” by Russ Cohen.

Cohen is a good friend of The Last Green Valley and is an expert on wild edible plants. He has led several walks and workshops on collecting edible plants and his book is available for sale through TLGV’s website.

His recipe for autumn olive fruit leather is included in the book and I can say from personal experience that it tastes wonderful. Like a fruit roll-up, the leathery consistency is fun to eat and the tart and tangy flavor is similar to cranberries. Here is some information of note from his book.

The fruit of the Russian olive is inferior to that of the autumn olive.

The fruit is available over a long period, from October well into November and occasionally even December.

The berries are high in vitamin C.

The autumn olive is easy to pick as the fruit-bearing branches are usually loaded with hundreds of fruit.

You should taste a fruit from each shrub before harvesting. Autumn olive fruit can vary considerably from shrub to shrub and some are too astringent.

When you find the right combination of sweetness and tartness, all the fruit should have the same great flavor.

The recipe that Cohen describes in his book calls for separating the fruit pulp from the seed by simmering the fruit until softened and then running it through a food mill to separate the seed from the pulp. If you don’t have a food mill you can mash the softened fruit and pour it into a sieve and stir it briskly. The sieve should hold back the seeds and the result is a frothy puree.

Cohen suggests using a food dehydrator and roll sheets. You simply pour the 100 percent autumn olive puree onto the liquid holding trays and roll sheets and run the dehydrator until it dries to the correct consistency, usually about 21 hours.

The autumn olive and Russian olive is a persistent invasive shrub with a very negative impact on our fields and open spaces. Despite the tasty usefulness of the fruit, I will continue to remove it from my property.

We live in a beautiful region full of amazing flora and fauna. I hope you’ll join me in caring for it, enjoying it and passing it on to the next generation.

Bill Reid is chief ranger of The Last Green Valley National Heritage Corridor and has lived in the region for more than 30 years. He can be reached at bill@tlgv.org.

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