Small-plot, low-dose treatments of triclopyr for selective control of Eurasian watermilfoil

  • Published source details Poovey A.G., Getsinger K.D., Skogerboe J.G., Koschnick T.J., Madsen J.D. & Stewart R.M. (2004) Small-plot, low-dose treatments of triclopyr for selective control of Eurasian watermilfoil. Lake and Reservoir Management, 20, 322-332.


Action: Use herbicide to control problematic plants

A replicated, paired, controlled, before-and-after study in 1998 in two lakes invaded by Eurasian watermilfoil Myriophyllum spicatum in Minnesota, USA (Poovey et al. 2004) found that treating plots with herbicide typically maintained, or minimized declines in, aquatic macrophyte richness and abundance. Comparing data from just before and eight weeks after herbicide application, total richness did not decline in seven of nine treated plots (for which before: 0.6–2.8; after: 0.8–3.6 species/survey point) but declined in two of three treated plots (for which before: 1.6–2.4; after: 0.5–1.4 species/survey point). The frequency of native macrophytes declined in both treated plots (before: present at 34–62% of survey points; after: 28–42%) and untreated plots (before: 35%; after: 11%) – but note that the decline was smaller in treated than untreated plots (not statistically tested). Eurasian watermilfoil cover declined in treated plots (before: 98–100%; after: 56–73%) but was stable in untreated plots (before: 99%; after: 100%). See original paper for data on the abundance of other individual species. Methods: A total of twelve 1-ha plots (three sets of four) were established in submerged macrophyte beds dominated by Eurasian watermilfoil. Triclopyr herbicide was applied to nine plots (three plots/set) in late June 1998. The dose was 0.5, 1.0 or 1.5 mg/L, depending on how sheltered or exposed the plot was. The final three plots (one plot/set) received no herbicide. Aquatic macrophytes were surveyed at 36 points/plot before intervention (20 June) and eight weeks after (3 August).

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