Evaluation of techniques for controlling non-native sea lavenders in California coastal salt marshes

Abstract

AbstractTwo species of non-native sea lavender, Limonium ramosissimum (Poir.) Maire (Algerian sea lavender) and Limonium duriusculum (Girard) Fourr. (European sea lavender) are prolific invaders of California salt marshes. We examined the efficacy of three non-herbicide treatments [tarping, selective removal (hand pulling), and scraping], and one herbicide (Telar®) treatment, in eliminating L. ramosissimum and L. duriusulum, as well as treatment impacts to native vegetation within three southern California salt marshes. Our experiments demonstrated that the non-herbicide treatments initially suppressed cover of L. ramosissimum and L. duriusulum to near zero but varied over time in their suppression of L. ramosissimum and L. duriusulum, and their effects on native species. Depending on the tarping duration, tarping eradicates L. ramosissimum and L. duriusulum at least a year post treatment with little to no long-term negative impacts to native vegetation. Selective removal had minimal effect on native species but did not consistently suppress L. duriusulum over time. Scraping eradicates L. ramosissimum and L. duriusulum; however, its negative impacts on native species make it an undesirable treatment across large areas. The herbicide treatment was not as effective in suppressing L. ramosissimum, either initially or over time, and it negatively impacted native species. Our findings support the use of tarping as the primary management method to control or eradicate dense infestations of L. ramosissimum and L. duriusulum in salt marshes. We suggest that a combination of tarping and selective removal be used to control L. ramosissimum and L. duriusulum in areas of lower infestation.