Mowing. Mowing for weed control in forages is generally not very effective (Miller and Strizke 1995) because it is non-selective and may occur too late to reduce competition between weeds and the seedlings. Mitchell et al. (2010a) recommended mowing just above the switchgrass canopy (typically 20 to 30 cm) near the 4th of July to reduce the leaf area of both grassy and broadleaf weeds in newly-seeded switchgrass stands. Mowing can reduce competition for light, and can prevent weeds from going to seed and contributing to the soil seed bank. It is sometimes the only option to suppress grassy weeds, especially when trying to establish switchgrass where herbicides are not effective.

Mob grazing. Mob-grazing is stocking a high density of animals in an area for a short duration (up to 1 wk). It reduces selective grazing by livestock, and thus, can be effective in the control of grass weeds and allowing sunlight to the new seedlings (Miller and Strizke 1995). However, grazing must be delayed until seedling roots are well established or the seedlings can be uprooted. Often, as with mowing, the efficacy of mob-grazing is only moderate, because it is applied too late to have maximum benefit in reducing weed competition for moisture, sunlight, and nutrients, and damage to the soil from foot traffic may be significant. Further, unpalatable weeds might not be grazed and the seedling forage may be preferred to weed species.

Cultivation (Tillage). The main use of cultivation in switchgrass has been for seedbed preparation to remove all vegetation prior to planting to help ensure good seed to soil contact. It is important to consider that tillage can bring dormant weed seeds to the surface, so it is often best plant into a stale seedbed after tillage. Under certain unique circumstances, tillage could be used post-planting to non-selectively control weeds between rows of switchgrass planted on wide row spacings.

Companion Crops. Companion crops are planted along with switchgrass to provide protection from wind and water erosion. Hintz et al. (1998) also reported companion crops could reduce weed competition during switchgrass establishment. For example, they reported that corn planted in perpendicular orientation at reduced seeding rates of 24,700 to 49,400 seeds ha1 on either 76 or 114 cm spacing did not reduce switchgrass establishment. They concluded that atrazine reduced weed emergence early season while the corn shaded the weeds during late season. It is important to illustrate that in this study, they planted following soybeans, and although grass weeds (foxtail) were present, they were not detrimental to the switchgrass in the control plots. Companion crops generally are not recommended except in extreme environments and conditions; cover crops may be best used when terminated prior to shading of the switchgrass seedlings. In Oklahoma, cowpea (Vigna unguiculata L. Walp) and forage sorghum (Sorghum bicolor (L.) Moench.) planted in perpendicular or alternating drill row orientations were too competitive with switchgrass seedlings and complete stand failure occurred when these crops were harvested at the end of season (T. J. Butler, unpublished data). Cowpea could be a viable cover crop if planted with an alternating row pattern, since it can be removed with 2,4-D amine once it begins to shade the switchgrass seedlings (Fig. 3). This alternating row pattern can be accomplished with drill containing two seed boxes, one for each species, and plugging every other hole of each drill box. However, care should be taken to ensure each planter unit is calibrated at the appropriate depth for each species.