Management of Cenchrus setaceus in the USA
Cenchrus setaceus (Poaceae: EPPO List of Invasive Alien Plants) is a popular ornamental plant that has been widely planted in gardens and parks. It is native to Africa and has become invasive in Hawaii and the southern continental United States, Australia, the Canary Islands and Southern Europe. It can have a negative impact on native biodiversity and ecosystem services. Experiments were conducted in North America (Sonoran Desert, Arizona) to assess cost-effective removal efforts that also protect the surrounding native plant community. Experiments were conducted in Arizona from March 2018 to March 2021 in 5 m × 5 m plots to test the efficacy and record costs for common removal techniques (cut and herbicide treatment, herbicide treatment one or two times per year and manual removal (digging up the plants)). Each treatment took 2.5 years to achieve control in the plots, and treatments did not negatively affect the native plant community. Plots that received the manual removal treatment had on average almost five more native plant species than the control treatment. Herbicide (glyphosate) applied in spring and autumn increased efficacy of removals in the first year but was not significantly different from the other treatments averaged over the year. Herbicide applied once per year was most cost effective across different sized areas. Manual removal was also cost effective in small areas (< 0.06 hectares) but was more expensive than herbicide applied twice a year in larger areas. The authors concluded that their results provide a toolset that enables managers to select removal treatments based on a balance of convenience, resources, and scale of the infestation.
Sources
Rowe HI, Sprague TA, Staker P (2022) Comparing common fountain grass removal techniques: cost efficacy and response of native plant community. Biological Invasions 24, 3817-3830.