Silverthorn Elaeagnus pungens (Thunb.) Elaeagnaceae

Biology Evergreen shrub, but may also climbEvergreen shrub, but may also climb Introduced from China and Japan in early 1800’sIntroduced from China and Japan in early 1800’s Tolerates drought, shade and salinityTolerates drought, shade and salinity Silvery thorns on branches, hence common nameSilvery thorns on branches, hence common name

Background Economic Uses Cultivated as an ornamentalCultivated as an ornamental Evergreen hedge and roadside barrier plantEvergreen hedge and roadside barrier plant

Distribution Found in isolated areas of north and central FloridaFound in isolated areas of north and central Florida Found along roadways and disturbed areas, forest edges, waterwaysFound along roadways and disturbed areas, forest edges, waterways –Generally as a direct escape from cultivation

Silverthorn Distribution in Florida

Impacts Category II invasive species (FLEPPC)Category II invasive species (FLEPPC) –Limited spread into undisturbed sites Displaces native vegetation, climbs into trees and shades understory plantsDisplaces native vegetation, climbs into trees and shades understory plants Can hybridize with native Elaeagnus speciesCan hybridize with native Elaeagnus species

Identification

Mature Plant Evergreen shrub, grows 3 to 25 feet tallEvergreen shrub, grows 3 to 25 feet tall May climb into tree canopiesMay climb into tree canopies Rambling appearance – multiple stemsRambling appearance – multiple stems Seedling plantSeedling plant

Leaves Alternate arrangedAlternate arranged Rough & grainyRough & grainy Wavy marginsWavy margins Scaly upper leaf surface, silvery lower leaf surfaceScaly upper leaf surface, silvery lower leaf surface Reddish brown bark, lenticels on older plantsReddish brown bark, lenticels on older plants

Flowers and Fruit Flowers are pale yellow, bell-shapedFlowers are pale yellow, bell-shaped Sweet smelling fragranceSweet smelling fragrance Fruit are round drupes, red with silver scalesFruit are round drupes, red with silver scales

Management PreventativeCulturalMechanicalBiologicalChemical

Preventative 1.Limit planting as an ornamental 2.Remove existing plants, including resprouts and before seeds are produced 3.Rouge out plants in abandoned areas

Cultural 1.Alternative landscape plants to replace silverthorn 2.Programs to educate homeowners about the problems associated with silverthorn and proper identification 3.Maintain good ground cover and mixture of plant species to reduce establishment

Biological 1.There are no known biological control agents available for silverthorn management in Florida or the southeastern U.S.

Mechanical 1.Hand pull young seedlings, including all roots, repeated pulling for resprouts 2.Cut plant down at ground level 3.Mowing is effective on small bushes and resprouts, but must be repeated

Chemical - Foliar 1.Over-the-top applications for seedlings, resprouts and small plants 2.Thoroughly wet leaves with herbicide Triclopyr – 2% solution Triclopyr – 2% solution Glyphosate – 2 to 3% solution Glyphosate – 2 to 3% solution Imazapyr to 1.0% solution Imazapyr to 1.0% solution Use surfactant at 0.25% Use surfactant at 0.25% 3.Best results applied before fruiting

Chemical - Basal 1.Individual trees, near desirable species 2.Use 25% triclopyr solution with basal oil 3.Apply 12 to 15 inches above ground on stems 4.Wet thoroughly for good control, spray until run-off is noticeable at ground line

Chemical – Cut Stump 1.Individual stems, near desirable species 2.Cut trunks/stems horizonally at or near ground level 3.Apply 25% solution of glyphosate or triclopyr, 10% solution of imazapyr 4.Cover the outer 20% of the stump 5.Marker (blue) dye is helpful

Useful Links Invasive and Exotic Species of North America: University of Florida Center for Aquatic and Invasive Plants: University of Florida’s Cooperative Extension Electronic Data Information Source:

Useful Links USDA Natural Resources Conservation Service, Plants Database: Plant Invaders of Mid-Atlantic Natural Areas: midatlantic/indexsci.htm midatlantic/indexsci.htm

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