Study

Efficacy, selectivity, and herbicide concentrations following a whole-lake 2,4-D application targeting Eurasian watermilfoil in two adjacent northern Wisconsin lakes

  • Published source details Nault M.E., Netherland M.D., Mikulyuk A., Skogerboe J.G., Asplund T., Hauxwell J. & Toshner P. (2014) Efficacy, selectivity, and herbicide concentrations following a whole-lake 2,4-D application targeting Eurasian watermilfoil in two adjacent northern Wisconsin lakes. Lake and Reservoir Management, 30, 1-10.

Summary

Action: Use herbicide to control problematic plants

A replicated, controlled, before-and-after study in 2006–2012 of two lakes invaded by Eurasian watermilfoil Myriophyllum spicatum in Wisconsin, USA (Nault et al. 2014) reported that the effect of adding herbicide on native submerged macrophytes depended on the dose. Unless specified, statistical significance was not assessed. At both high and low doses, watermilfoil was less abundant in the 2–5 years after adding herbicide than in the 2–4 years before. There was a significant decline in its frequency (before: present at 26–42% of survey points, vs after: 0–8%) and a clear decline in its above-ground biomass (before: 4–17 g/site; after: <0.3 g/site). Both doses reduced total submerged macrophyte biomass (before: 9–19 g/site; after: <1–5 g/site). However, the higher herbicide dose suppressed native macrophyte richness (before: 21; after: 11 species) and biomass (before: 6 g/site; after: <1–2 g/site). It led to significant, sustained reductions (for ≥5 years) in the frequency of five native macrophyte species (see original paper for data). These changes did not occur a lake that had not yet been treated. In contrast, the lower herbicide dose had no clear effect on native macrophyte richness (before: 13–17; after: 16–17 species) or biomass (before: 3–7 g/site; after: 4–5 g/site). It led to significant, sustained reductions (for ≥2 years) in the frequency of only two native macrophyte species (see original paper for data). Methods: Two adjacent lakes were treated with 2,4-D herbicide: one lake with a higher dose (around 600 µg/L near surface) in May 2008, one lake with a lower dose  (around 375 µg/L near surface) in May 2011. Submerged macrophytes were surveyed in a grid of points each summer 2006–2012 (324–427 points/lake/year). This captured periods before and after herbicide application in each lake. Biomass was dried before weighing.

Output references
What Works 2021 cover

What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read the latest volume: Volume 18

Go to the CE Journal

Discover more on our blog

Our blog contains the latest news and updates from the Conservation Evidence team, the Conservation Evidence Journal, and our global partners in evidence-based conservation.


Who uses Conservation Evidence?

Meet some of the evidence champions

Endangered Landscape Programme Red List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Bern wood Supporting Conservation Leaders National Biodiversity Network Sustainability Dashboard Frog Life The international journey of Conservation - Oryx British trust for ornithology Cool Farm Alliance UNEP AWFA Butterfly Conservation People trust for endangered species Vincet Wildlife Trust