Silverthorn

1. Silverthorn Elaeagnus pungens (Thunb.) Elaeagnaceae

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

3. Background Economic Uses • Cultivated as an ornamental • Evergreen hedge and roadside barrier plant

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

5. Silverthorn Distribution in Florida

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

7. Identification

8. Mature Plant • Evergreen shrub, grows 3 to 25 feet tall • May climb into tree canopies • Rambling appearance – multiple stems • Seedling plant

9. Leaves • Alternate arranged • Rough & grainy • Wavy margins • Scaly upper leaf surface, silvery lower leaf surface • Reddish brown bark, lenticels on older plants

10. Flowers and Fruit • Flowers are pale yellow, bell-shaped • Sweet smelling fragrance • Fruit are round drupes, red with silver scales

11. Management Preventative Cultural Mechanical Biological Chemical

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

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

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

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

16. Chemical - Foliar • Over-the-top applications for seedlings, resprouts and small plants • Thoroughly wet leaves with herbicide • Triclopyr – 2% solution • Glyphosate – 2 to 3% solution • Imazapyr - 0.5 to 1.0% solution • Use surfactant at 0.25% • Best results applied before fruiting

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

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

20. Useful Links Invasive and Exotic Species of North America: www.invasive.org University of Florida Center for Aquatic and Invasive Plants: http://aquat1.ifas.ufl.edu/welcome.html University of Florida’s Cooperative Extension Electronic Data Information Source: http://edis.ifas.ufl.edu/index.html

21. Useful Links USDA Natural Resources Conservation Service, Plants Database: http://plants.usda.gov Plant Invaders of Mid-Atlantic Natural Areas: http://www.nps.gov/plants/alien/pubs/midatlantic/indexsci.htm

22. Literature Cited 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