Elaeagnus pungens

Silverthorn

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Introduction

In the early 1800’s Elaeagnus pungens, or silverthorn,was introduced from China and Japan as an ornamental plant. Silverthorn is used in the United States as a landscape plant, often grown as an evergreen hedge and barrier and is regularly planted along highways. Unfortunately, many Florida nurseries and homeowners are not aware the Florida Exotic Pest Plant Council considers this plant a Category II invasive exotic species. This means silverthorn has the potential to cause ecological damage by altering naive plant communities by hybridizing with native Elaeagnus species, displacing native species, and changing community structures or ecological functions.

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Description

Elaeagnus pungens is an evergreen shrub that is able to grow 3 to 25 feet in height. Although silverthorn is primarily considered a shrub, it also can take the form of a climbing plant, growing over and shading out other plants. Take caution when handling this plant. Its common name, silverthorn, comes from the thorns on its branches.

Leaves are lanceolate with entire to wavy margins arranged alternately on the stem approximately 2 to 4 inches long (0.2 to 2 inches wide).  Upper leaf surfaces are waxy green and scaly. Lower leaf surfaces are silvery and scaly, as is the petiole. To the touch, leaves are rough and grainy.  The bark is reddish brown in color, having lenticels (small spots) when older, smooth when young. 

Flowers are 1/2 to 5/8 inch long, pale yellow to white, bell shaped with a sweet smelling fragrance.  These are borne in axillary clusters of one to three flowers in the fall. The fruit are drupes, round and red in color with silver scales.

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Impacts

Silverthorn is a fast-growing, weedy ornamental. It is able to grow and thrive in a variety of conditions, and can tolerant shade, drought, and salt. Animals and birds disperse seed, widening its area of distribution. Reproduction also occurs via stem sprouts. When silverthorn is in the climbing form, it can climb into trees, leading to the displacement of native vegetation.

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Management

Preventative:

Remove all silverthorn plantings to prevent the spread and dispersal of seed. Educate the public on the potential dangers of invasive plants to prevent future plantings.

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Cultural:

Remove plants prior to seed production.  Revegetate natural areas with native species.

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Mechanical:

Aggressive tillage and/or mowing is an option whenever possible.  Repeat as needed to control regrowth. 

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Biological:

Silverthorn has very few pests or diseases in landscapes. There are no known biological agents.

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Chemical:  

Foliar applications of imazapyr or glyphosate with a surfactant in water have been used to treat silverthorn. Triclopyr as a 20% solution in a petroleum base with a penetrant can be used for upper stem treatments, as well as to young bark as a basal spray. Large stems can be cut and stumps treated immediately with imazapyr (10% solution), triclopyr (50% solution) or glyphosate (20% solution) in water with a surfactant.

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Helpful Notes:

Surfactant – 0.25% is the standard rate for all foliar herbicide applications, 2 teaspoons per gallon.

Dry time – generally 4-6 hours is adequate, but the longer the better for glyphosate

Pay particular attention to herbicide labels near wetlands or bodies of water.

The use of trade names in these publications is solely for the purpose of providing specific information. UF/IFAS does not guarantee or warranty the products named, and references to them in this publication does not signify our approval to the exclusion of other products of suitable composition. All chemicals should be used in accordance with directions on the manufacturer's label.

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References and Useful Links:

Invasive Plants of the Eastern United States

University of Florida Center for Aquatic and Invasive Plants

Langeland, K.A. and K. Craddock Burks. 1998. Identification and Biology of Non-Native Plants in Florida's Natural Areas. IFAS Publication SP 257. University of Florida, Gainesville. 165 pp.

USDA Natural Resources Conservation Service. Plants Database

Morgan, E.C. and W.A. Overholt. 2004. Wildland Weeds: Paper Mulberry, Broussonetia papyrifera. Publication ENY-702, Entomology and Nematology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida.

Plant Invaders of Mid-Atlantic Natural Areas

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