The effect of formulation and adjuvants on absorption and translocation of ¹⁴C-clethodim was determined at 1, 4, 12, 24, 48, and 72 h after treatment (HAT) in bermudagrass under greenhouse conditions. Absorption of ¹⁴C-clethodim with the 0.12 kg L⁻¹ (15 to 85%) formulation was higher than with the 0.24 kg L⁻¹ (5 to 40%) formulation, regardless of presence or absence of adjuvant. There was considerable variation in the effect of adjuvant on ¹⁴C-clethodim absorption. When either ammonium sulfate (AMS) or AMS plus crop oil concentrate (COC) was added to the 0.12 kg L⁻¹ formulation, ¹⁴C-clethodim absorption increased significantly at all harvest times except at 12 HAT compared with 0.12 kg L⁻¹ formulation alone, whereas, ¹⁴C-clethodim absorption after addition of COC to the 0.12 kg L⁻¹ formulation was similar to the 0.12 kg L⁻¹ formulation alone up to 24 HAT. Conversely, COC enhanced ¹⁴C-absorption at all harvest times when added to 0.24 kg L⁻¹ formulation. Most of ¹⁴C-clethodim (79 to 100% of absorbed) remained in the treated leaf, independent of formulation or adjuvant. Formulation did not have an impact on distribution of absorbed ¹⁴C-clethodim; however, presence of an adjuvant increased movement of ¹⁴C-clethodim out of treated leaf. Of the absorbed ¹⁴C-label, most remained in the treated leaf. ¹⁴C-clethodim that translocated out of the treated leaf remained in the shoot, and negligible amount of ¹⁴C-clethodim translocated to roots. These results demonstrated improved absorption of clethodim with formulations containing half the active ingredient (0.12 kg L⁻¹) and inclusion of both AMS and COC.

Nomenclature: Clethodim; bermudagrass, Cynodon dactylon (L.) Pers. CYNDA.