Published online by Cambridge University Press: 20 January 2017
Old World climbing fern (OWCF) is a highly invasive plant that is spreading rapidly and disrupting natural areas in Florida, with the potential to spread by wind-blown spores into Central and South America. Experiments were performed using gametophytes to determine the dose response of OWCF to metsulfuron methyl (metsulfuron). OWCF gametophytes were highly susceptible to metsulfuron with ≤ 1.4% survival at concentrations ≥ 27 mg ai L−1. Metsulfuron OWCF gametophyte 50 and 95% inhibition (I50 and I95) values were 6.1 and 26.4 mg ai L−1, respectively. Survival of treated gametophytes that developed into sporophytes was ≤ 0.014% at concentrations ≥ 27 mg ai L−1, but no sporophytes developed at concentrations ≥ 432 mg ai L−1. Metsulfuron OWCF sporophyte inhibition I50 and I95 values were 5.6 and 24.1 mg ai L−1, respectively. At 216 mg ai L−1 metsulfuron, half of the standard operational use rate, 1.1 × 10−8% of the treated gametophytes developed into sporophytes. The results indicate that the potential for tolerant, and potentially resistant, OWCF populations is higher using lower concentrations of metsulfuron as no gametophytes developed into sporophytes at the standard field treatment concentration of 432 mg ai L−1.
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