Evaluation of perennial pepperweed (Lepidium latifolium) management in a seasonal wetland in the San Francisco Estuary prior to restoration of tidal hydrology
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Published source details
Whitcraft C.R. & Grewell B.J. (2012) Evaluation of perennial pepperweed (Lepidium latifolium) management in a seasonal wetland in the San Francisco Estuary prior to restoration of tidal hydrology. Wetlands Ecology and Management, 20, 35-45.
Published source details Whitcraft C.R. & Grewell B.J. (2012) Evaluation of perennial pepperweed (Lepidium latifolium) management in a seasonal wetland in the San Francisco Estuary prior to restoration of tidal hydrology. Wetlands Ecology and Management, 20, 35-45.
Actions
This study is summarised as evidence for the following.
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Use herbicide to control problematic plants: brackish/salt marshes Action Link |
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Use herbicide to control problematic plants: brackish/salt marshes
A replicated, randomized, paired, controlled, before-and-after study in 2007–2009 in a brackish marsh invaded by perennial pepperweed Lepidium latifolium in California, USA (Whitcraft & Grewell 2012) found that spraying the vegetation with imazapyr herbicide reduced the richness and cover of non-target vegetation over two years, but that spraying the vegetation with 2,4D had no significant effect on these metrics. After two years, imazapyr-treated plots contained only 0.5 non-pepperweed plant species/0.25 m2 (vs 2,4D: 2.0 species/0.25 m2; untreated: 2.1 species/0.25 m2) and only 7% cover of plants other than pepperweed (vs 2,4D: 70%; untreated: 66%). Imazapyr-treated plots had only 1% cover of pepperweed (vs 2,4D: 26%; untreated: 31%), and above-ground pepperweed biomass was only 7 g/m2 (vs 2,4D: 29 g/m2; untreated: 40 g/m2). The pattern of results was similar after one year, although not the values of some metrics (e.g. only 3–34% cover of plants other than pepperweed). Before intervention, plots destined for each treatment had similar non-pepperweed richness (2.0–2.6 species/plot), non-pepperweed cover (30–35%), pepperweed cover (27–39%) and pepperweed biomass (87–110 g/m2). Methods: Thirty-six plots were established (in six blocks of six) in a degraded, historically tidal, brackish marsh. In 2007 and 2008, twelve plots (two plots/block) received each of three treatments: spraying with dyed imazapyr (Habitat®), spraying with dyed 2,4D (Weedar®) or no herbicide (spraying with dyed water only). Vegetation was surveyed in April before (2007) and after (2008, 2009) intervention. Plant species and cover were recorded in three 0.25-m2 quadrats/plot. Pepperweed was cut from three 0.125-m2 quadrats/plot then dried and weighed.
(Summarised by: Nigel Taylor)
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