Event Title

Hard to Kill: Hybrid Watermilfoil are Less Sensitive to a Commonly Used Herbicide

Location

Exhibition Hall, DeVos Center

Start Date

10-4-2012 3:30 PM

Description

PURPOSE: The Eurasian watermilfoil and its hybrid with native northern watermilfoil are both widespread invaders that are extensively managed with herbicides. Recent reports by lake managers suggest this hybrid does not respond as well to commonly used herbicides, but very few studies have tested whether or not hybrids are less susceptible to herbicides. In the Menominee River Watershed, in the Western Upper Peninsula of Michigan, hybrids occur more often than parental species in herbicide (2,4-D) treated lakes than untreated lakes. This suggests hybrids may have a competitive advantage in environments where herbicides are commonly used. To test the hypothesis that hybrids are less 2,4-D susceptible than Eurasian watermilfoil, we conducted a herbicide sensitivity assay. SUBJECTS: We experimentally compared 2,4-D sensitivity of six hybrid and four Eurasian watermilfoil populations from the Menominee River Watershed, in addition to a second experiment where we compared 2,4-D sensitivity of six hybrid and nine Eurasian watermilfoil populations from the Lower Peninsula of Michigan. METHODS AND MATERIALS: 2,4-D sensitivity assays were conducted in mesocosms. ANALYSES: A two-way nested analysis of variance was used to compared hybrid and Eurasian watermilfoil 2,4-D sensitivity. RESULTS: Hybrids were less sensitive to 2, 4-D than Eurasian watermilfoil. CONCLUSIONS: If hybrids are less likely to respond to commonly used herbicides, new management strategies may be needed to increase the efficiency of chemical usage in freshwater ecosystems.

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Apr 10th, 3:30 PM

Hard to Kill: Hybrid Watermilfoil are Less Sensitive to a Commonly Used Herbicide

Exhibition Hall, DeVos Center

PURPOSE: The Eurasian watermilfoil and its hybrid with native northern watermilfoil are both widespread invaders that are extensively managed with herbicides. Recent reports by lake managers suggest this hybrid does not respond as well to commonly used herbicides, but very few studies have tested whether or not hybrids are less susceptible to herbicides. In the Menominee River Watershed, in the Western Upper Peninsula of Michigan, hybrids occur more often than parental species in herbicide (2,4-D) treated lakes than untreated lakes. This suggests hybrids may have a competitive advantage in environments where herbicides are commonly used. To test the hypothesis that hybrids are less 2,4-D susceptible than Eurasian watermilfoil, we conducted a herbicide sensitivity assay. SUBJECTS: We experimentally compared 2,4-D sensitivity of six hybrid and four Eurasian watermilfoil populations from the Menominee River Watershed, in addition to a second experiment where we compared 2,4-D sensitivity of six hybrid and nine Eurasian watermilfoil populations from the Lower Peninsula of Michigan. METHODS AND MATERIALS: 2,4-D sensitivity assays were conducted in mesocosms. ANALYSES: A two-way nested analysis of variance was used to compared hybrid and Eurasian watermilfoil 2,4-D sensitivity. RESULTS: Hybrids were less sensitive to 2, 4-D than Eurasian watermilfoil. CONCLUSIONS: If hybrids are less likely to respond to commonly used herbicides, new management strategies may be needed to increase the efficiency of chemical usage in freshwater ecosystems.