Safeners are a group of chemically diverse compounds with the unique ability to protect grass crops from herbicide injury without reducing herbicide activity in target weed species (Davies and Caseley 1999; Hatzios and Burgos 2004). Most herbicide safeners were developed for corn, sorghum (Sorghum bicolor L.), rice (Oryza sativa L.), and wheat (Triticum aestivum L.) (Walton and Casida 1995; Hatzios and Burgos 2004). Fluxofenin is an oxime ether derivative primarily used to protect grasses from chloroacetanilide herbicides like metolachlor (Anonymous 2002; Anonymous 2004; Hatzios and Burgos 2004). Griffin et al. (1988) reported that switchgrass seedlings were safened against metolachlor with NA (1,8-napthalic anhydride), which is no longer commercially available. There has been relatively little research evaluating seed safeners to improve forage establishment (Roder et al. 1987). Butler et al. (unpublished data) observed that applications of metolachlor, metolachlor + atrazine, and pendamethalin reduced switchgrass emergence by 89 to 99 percentage points relative to untreated seed. Fluxofenin applied at 2 to 8 g a. i. kg-1 did not improve switchgrass emergence with any of these herbicide treatments. All seedlings died within three weeks of emergence, presumably due to lack of root development. Thus, fluxofenin does not appear to have potential for improving switchgrass establishment with metolachlor.

Activated charcoal is a well-documented herbicide safener (Becker and Wilson 1978; Yelverton et al. 1991) due to its large surface area and high adsorptive capacity (Coffey and Warren 1969; Cheremisinoff and Morresi 1978). Lee (1973) reported that 336 kg ha-1 activated charcoal in a 2.5-cm band effectively safened six grass species when applied with atrazine and diuron 3-[3,4-dichlorophenyl]-1,1-dimethylurea. However, there is limited information on charcoal as an herbicide safener on switchgrass.

Butler et al. (unpublished data) found that coating switchgrass seeds with activated charcoal safened switchgrass seedlings against metolachlor and metalochlor + atrazine, but reduced germination and emergence by 51 to 59% when rainfall was greater than normal. In addition, charcoal coated seeds failed to germinate and emerge in the field when rainfall conditions were below normal. Because charcoal is negatively charged, it may actually repel water, requiring greater amounts of water for seed to germinate. Given these inconsistent results, activated charcoal would not be recommended at this time. However, activated charcoal may have potential in regions with greater rainfall or in specialized areas with irrigation. Further testing and economic analyses are needed since charcoal seed coating treatments cost an average of $0.15 per 1,000 seeds. Addition of charcoal coating would increase costs approximately $454 ha1. This calculation also did not include cost of seed ($44 kg1), chemical ($37 ha1), shipping, and other variable establishment costs (land preparation, fertilizer, drill, and labor). In order for charcoal coated seed to become viable, seeding rate would need to be reduced, charcoal coating cost must be reduced, and coating material should not impede water inhibition, germination, and emergence.