Formulation and Adjuvant Effects on Uptake and Translocation of Clethodim in Bermudagrass (Cynodon dactylon)

The effect of formulation and adjuvants on absorption and translocation of C-clethodim was determined at 1, 4, 12, 24, 48, and 72 h after treatment (HAT) in bermudagrass under greenhouse conditions. Absorption of C-clethodim with the 0.12 kg L (15 to 85%) formulation was higher than with the 0.24 kg L (5 to 40%) formulation, regardless of presence or absence of adjuvant. There was considerable variation in the effect of adjuvant on C-clethodim absorption. When either ammonium sulfate (AMS) or AMS plus crop oil concentrate (COC) was added to the 0.12 kg L formulation, C-clethodim absorption increased significantly at all harvest times except at 12 HAT compared with 0.12 kg L formulation alone, whereas, C-clethodim absorption after addition of COC to the 0.12 kg L formulation was similar to the 0.12 kg L formulation alone up to 24 HAT. Conversely, COC enhanced C-absorption at all harvest times when added to 0.24 kg L formulation. Most of C-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 Cclethodim; however, presence of an adjuvant increased movement of C-clethodim out of treated leaf. Of the absorbed C-label, most remained in the treated leaf. C-clethodim that translocated out of the treated leaf remained in the shoot, and negligible amount of C-clethodim translocated to roots. These results demonstrated improved absorption of clethodim with formulations containing half the active ingredient (0.12 kg L) and inclusion of both AMS and COC. Nomenclature: Clethodim; bermudagrass, Cynodon dactylon (L.) Pers. CYNDA.