Published online by Cambridge University Press: 20 January 2017
Field studies were used to examine the management strategies of mowing,herbicide, fertility, and all possible combinations on tall ironweedpopulations, weed biomass, and pasture yield at three Kentucky locations.Mowing was performed in July 2008 and 2009, herbicide was applied in August2008, and fertilizer was applied in September 2008 and 2009 at alllocations. Weed populations were measured in 2008, 2009, and 2010, andforage grass, clover, and weed biomass was collected in May or early June of2009 and 2010. All treatments with herbicide reduced tall ironweed stems by64% or greater in 2009 at all locations. Mowing alone, fertilizer alone, andmowing plus fertilizer did not reduce tall ironweed populations, except atone location where mowing alone reduced tall ironweed stems by 64% in 2009.Tall ironweed stems were not reduced in 2010 with any treatment at twolocations, but herbicide combined with mowing or fertilizer reduced tallironweed stems by 78% at the other location. Tall goldenrod population wasreduced up to 100% by all treatments with herbicide or mowing alone, andmowing with fertilizer reduced tall goldenrod from 59 to 89%. Treatments didnot reduce horsenettle populations. Herbicide-containing treatments reducedweed biomass at all locations. Weed biomass did not differ when comparingall treatments with and without mowing or treatments with or withoutfertilizer. Forage grass biomass was greatest with herbicide plus fertilizerand with the combination of mowing plus herbicide plus fertilizer at alllocations in both years.