Observational monitoring of biological control vs. herbicide to suppress leafy spurge (Euphorbia esula) for eight years

Abstract

The effectiveness of Aphthona flea beetles (87 percent A. lacertosa Rosenhauer and A. czwalinae Weise, and 13 percent A. nigriscutis Foudras) as biological control agents of leafy spurge, Ephorbia esula L. was compared with a single application of herbicide (picloram) and untreated plots for a period of 8 years. Percentage of cover of leafy spurge, grasses; and flea beetle numbers were measured each year from 2000 through 2007. Cover of leafy spurge on Aphthona biological control plots exhibited annual declines until 2005. In 2006, these plots showed a temporary rebound in leafy spurge coverage followed by a decline in 2007. Spurge cover increased on the herbicide-treated plots and remained unchanged on the untreated check plots from 2000 through 2003. In 2003, the flea beetles began to emigrate from the release points within the biological control plots and dispersed throughout much of the surrounding leafy spurge infested area including the herbicide treated and check plots. This dispersal and colonization caused a subsequent decline in spurge cover on the herbicide-treated and control plots from 2004 through 2007.

Citation

Progar, R. A.; Markin, G.; Scarbrough, D.; Jorgensen, C. L.; Barbouletos, T. 2013. Observational monitoring of biological control vs. herbicide to suppress leafy spurge (Euphorbia esula) for eight years. In: Wu, Yun; Johnson, Tracy; Sing, Sharlene; Raghu, S.; Wheeler, Greg; Pratt, Paul; Warner, Keith; Center, Ted; Goolsby, John; Reardon, Richard, eds. Proceedings of the XIII International Symposium on Biological Control of Weeds; September 11-16, 2011; Waikoloa, Hawaii, USA. Session 9: Post-release Evaluation and Management. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Forest Health Technology Enterprise Team. Online: http://www.invasive.org/proceedings/pdfs/Progar.pdf