|Koger Iii, Clifford|
Submitted to: Weed Biology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/6/2007
Publication Date: 12/1/2007
Citation: Nandula, V.K., Poston, D.H., Reddy, K.N., Koger III, C.H. 2007. Formulation and adjuvant effects on absorption and translocation of 14**c-clethodim in wheat (Tritichum aestivum L). Weed Biology and Management 7:226-231. Interpretive Summary: Clethodim a postemergent grass herbicide registered for use in cotton and soybean is commercially available as a 0.24 kg/L formulation. A newer formulation with half the strength (0.12 kg/L) is under commercialization. Scientists from Delta Research and extension Center, Mississippi State University and Southern Weed Science Research Unit, Stoneville, MS have examined the efficacy of newer formulation and adjuvants on efficacy, uptake, and movement in wheat. Uptake of clethodim with the 0.12 kg/L formulation was higher than with the 0.24 kg/L formulation, regardless of presence or absence of adjuvant. Addition of adjuvant increased uptake of clethodim with the 0.12 kg/L formulation compared to no adjuvant. There were no differences in clethodim uptake among adjuvants (ammonium sulfate, crop oil concentrate or both) added to the 0.12 kg/L formulation. Most of clethodim absorbed remained in the treated leaf independent of formulation or adjuvant. Formulation did not have an impact on distribution of absorbed clethodim; however presence of an adjuvant increased movement of clethodim out of treated area. These results demonstrated improved absorption of clethodim with formulation containing half the active ingredient (0.12 kg/L) and inclusion of both adjuvants.
Technical Abstract: The effect of formulation and adjuvants on absorption and translocation of 14C-clethodim was determined at 1, 4, 12, 24, 48 and 72 hours after treatment (HAT) in wheat. Absorption of 14C-clethodim with the 0.12 kg L-1 (44 to 90% of applied) formulation was higher than with the 0.24 kg L-1 (16 to 37% of applied) formulation, especially at 24 HAT and beyond, regardless of presence or absence of adjuvant. Addition of adjuvant increased absorption of 14C-clethodim with the 0.12 kg L-1 formulation at all harvest times (16 to 90% of applied with adjuvant vs. 1 to 71% of applied without adjuvant), except at 72 HAT. However, there were no differences in 14C-clethodim absorption among adjuvants (ammonium sulfate, crop oil concentrate or both) added to the 0.12 kg L-1 formulation, except at 48 and 72 HAT. Most of 14C-clethodim (73 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. Autoradiograms indicated 14C-clethodim did not translocate appreciably to all parts of the plant. Of the absorbed 14C-label, most remained in the treated leaf.