Overcoming the Antagonistic Effect from Spray Carrier Minerals on Imazethapyr Activity

• Published in: Agronomy journal 2014-09, Vol.106 (5), p.1569-1573
• Main Authors: Aliverdi, A., Ganbari, A., Rashed-Mohassel, M.H., Nassiri-Mahallati, M., Zand, E.
• Format: Article
• Language: English
• ISSN: 0002-1962; 1435-0645
• DOI: 10.2134/agronj13.0514

Minerals in spray carrier water can adversely influence the activity of weak acid herbicides, thus overcoming them has been considered a main research priority. A series of dose–response pot experiments were conducted to compare the water softening chemical methods [(NH4)2SO4, NH4NO3, C6H8O7, and KHPO4] and a new water softening physical method (passing through a magnetic field of 0.7 T) for overcoming antagonism from the carriers containing 0.5 g L−1 of CaCO3, MgCO3, Na2CO3, K2CO3, or Fe2(CO3)3 on imazethapyr (2‐[4,5‐dihydro‐4‐methyl‐4‐(1‐methylethyl)‐5‐oxo‐1H‐imidazol‐2‐yl]‐5‐ethyl‐3‐pyridinecarboxylic acid) activity on jimsonweed (Datura stramonium L.). The imazethapyr activity was significantly increased by all methods when distilled water was used as the carrier. The (NH4)2SO4 (relative potency [RP] = 3.52) was the most effective method, followed by C6H8O7 and NH4NO3 (RP = 2.58), a magnetized carrier (RP = 1.83), and then KHPO4 (RP = 1.48) to improve imazethapyr activity. The imazethapyr activity was clearly antagonized when carbonate salts were added to distilled water. The intensity of the antagonistic effects depended on the cation's valence and ranked as Fe2(CO3)3 (RP = 0.47) > MgCO3 (RP = 0.52) = CaCO3 (RP = 0.53) > K2CO3 (RP = 0.69) = Na2CO3 (RP = 0.66). The application of a magnetized carrier was not as effective a method for overcoming this antagonism as the addition of (NH4)2SO4 or C6H8O7, but it was more effective than the addition of NH4NO3 or KHPO4. Nonetheless, from different points of view—agronomic, environmental, and economic—applying a magnetized carrier is recommended as a technique because it not only needs no chemical but it also causes no side effects.