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The invasive yellow bluestem (Bothriochloa ischaemum [L.] Keng) threatens native biodiversity, and its control is of interest to land managers involved in restoration of invaded grasslands. We used single, double, and triple applications of glyphosate (2.125 kg ai Á ha À1 Á application À1) over the course of one growing season in combinations at different timings (early, middle, late season) with and without a mechanical treatment of mowing or burning to determine the most effective control method. One year after treatment, burning and mowing prior to a mid-season single or double early, middle, and/or late season herbicide application resulted in a similar level of control of yellow bluestem relative to a triple herbicide application, all of which had greater control relative to herbicide treatment alone. Reproductive tiller density and visual obstruction increased 2 yr after treatment with two herbicide treatments applied either early and middle season or early and late season, but it was prevented with burning and mowing prior to herbicide application. With the exception of three herbicide applications, combining burning or mowing with herbicide applications provided more effective control of yellow bluestem than any individual herbicide applications. Burning or mowing likely improves glyphosate effectiveness by altering the invasive grass structure so that plants are clear of standing dead and have shorter, active regrowth to enhance herbicide effectiveness. During restoration projects requiring control of invasive yellow bluestem, an effective management option is a combination of mechanical and chemical control.

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Bermudagrass [Cynodon dactylon (L.) Pers.] is the most common warm-season introduced forage species grown in the southern portion of the United States. Often grown as a monoculture, bermudagrass responds well to fertilizer and intensive management but provides little wildlife or microbial soil community benefits due to the lack of species diversity. A methods study to evaluate methods of increasing diversity of bermudagrass by adding switchgrass (SG) or a native warm-season grass mixture (NGMIX) was conducted in southern Oklahoma. An established bermudgrass stand was suppressed using either 7, 11, or 19 months of seedbed preparation time (PREP) with either zero, one, two, or three cover crops depending on PREP time and applied to either till or no-till strips. Initiation of PREP times were staggered so a common date for SG and NGMIX planting was achieved in two consecutive planting years, April 2011 (Year 1) and April 2012 (Year 2). On both soil textures, till establishment increased stand frequency of SG and NGMIX the year of establishment compared to no-till. Stand frequency was repeated in 2015 (3 and 4 years post planting, respectively). The loam soil, no-till stand frequency counts in 2015 had improved for SG and NGMIX and were similar to till. The sandy loam site 2015 stand frequency counts of till established SG and NGMIX remained higher than no-till. No-till establishment was slower than and not as successful as till but it still achieved plant diversity in bermudagrass at a lower cost compared to till. Cover crops and PREP time had little effect on establishment. INTRODUCTIONThere are multiple reasons to consider establishing native warm-season grasses into bermudagrass [Cynodon dactylon (L.