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Control of hay-scented and New York ferns with Oust Xp® herbicide: Revisiting rate and timing required in mixed oak and northern hardwood stands

Informally Refereed

Abstract

Dense rhizomatous fern layers compete with desirable tree seedlings for light, which suppresses development and even kills seedlings. Sulfometuron methyl (Oust XP®) herbicide can be safely and effectively used to control ferns. Previous research showed that depending on application timing, as little as 2 ounces of Oust XP per acre controlled ferns while hardwood tree seedlings growing beneath them survived. It was recently suggested that some sites may require higher rates because of soil differences. This study uses a wider variety of site conditions than previous studies to reevaluate the rates and timing of Oust application. This study examined the efficacy of 2, 3, and 4 ounces of Oust XP herbicide per acre applied in July, August, and September without a surfactant for controlling Dennstaedtia punctilobula and Thelypteris nove-boracensis (hay-scented and New York ferns) in mixed oak and northern hardwood forests. Ten-foot by ten-foot plots were treated and monitored for fern control and impacts on nontarget species within 10 stands across north-central and northwestern Pennsylvania. Ferns were controlled with all rates and times of application. More surviving ferns in plots were treated in September. Hardwood seedlings survived even at the highest rate. Prunus serotina and Amelanchier arborea had some nonsignificant reductions in numbers at all rates and times. Some growth malformations were noticed on individual seedlings with July treatments. Oust XP killed Rubus spp. (blackberry) at all rates and times, but grasses and other herbs were unaffected. Oust XP continues to be an effective tool for controlling ferns at a variety of sites and allows seedlings to survive in place.

Parent Publication

Citation

Ristau, Todd E. 2017. Control of hay-scented and New York ferns with Oust Xp® herbicide: Revisiting rate and timing required in mixed oak and northern hardwood stands. In: Kabrick, John M.; Dey, Daniel C.; Knapp, Benjamin O.; Larsen, David R.; Shifley, Stephen R.; Stelzer, Henry E., eds. Proceedings of the 20th Central Hardwood Forest Conference; 2016 March 28-April 1; Columbia, MO. General Technical Report NRS-P-167. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station: 11-18.
https://www.fs.usda.gov/research/treesearch/53752