Overcoming Antagonistic Effects of Na-Bentazon on Sethoxydim Absorption

The influence of adjuvants, inorganic salts, and herbicide formulations on the antagonistic effect of Na-bentazon on sethoxydim absorption was studied in quackgrass. Adjuvant BCH 815 00, at 2.4 L ha −1 alone or at 1.2 L ha −1 combined with 1.1 kg ha −1 of ammonium sulfate, added to the sethoxydim and Na-bentazon spray mixture overcame the antagonism on 14 C-sethoxydim absorption in quackgrass. Crop oil concentrate at rates up to 9.6 L ha −1 did not overcome the antagonism. Adding ammonium phosphate or ammonium nitrate to the spray solution was as effective as adding ammonium sulfate in overcoming the antagonism caused by reduced absorption of sethoxydim even from the combination of Na-bentazon plus Na-acifluorfen. Ammonium salts and NH 4 -bentazon overcame the antagonism of Na-bentazon by forming readily absorbed NH 4 -sethoxydim.