The Effect of Ammonium Sulphate on Efficacy of a Few Weak Acidic Herbicides

This research was carried out in 2009 at greenhouse of Iranian Research Institute of Plant Protection to determine the effect of water quality on weak acidic herbicides in control of Picnomon acarna (L.) Cass, as indicator plant, in wheat and canola. Clopyralid, glyphosate and 2,4-D+MCPA were applied, respectively, at 0.24, 2.64 and 0.72 kg ae ha-1. Each herbicide dissolved in water contained ammonium sulfate (AS) at concentration of 2, 4 or 8 percent, sprayed on the target plants at initial growth stage. AS, parallel to increasing the concentration, enhanced electric conductivity and reduced the pH of herbicide solutions. Adding AS into glyphosate or clopyralid, significantly reduced the percentage of the weed plants. Based on dry weight evaluation, AS had no significant effect on the efficacy of 2,4-D+MCPA or clopyralid. For reducing the number of plant of the weeds, 2,4-D+MCPA without AS was more effective than its solution solute in water contained AS. Adding AS into the solution of clopyralid had to effect on wheat and canola. Similar result obtained with 2,4-D+MCPA on wheat.