EFFECT OF OIL AND MINERAL ADJUVANTS ON EFFICACY AND PHYSICO-CHEMICAL PROPERTIES OF FORAMSULFURON AND IODOSULFURON SPRAY MIXTURE

The effect of adjuvant on physico-chemical properties and efficacy of foramsulfuron + iodosulfuron mixture was evaluated. Foramsulfuron + iodosulfuron at recommended rate (45 + 1.5 g ha^-1) and at reduced rate (22.5 + 0.75 g ha^-1) was applied with petroleum oil (PO), two methylated rapeseed seed oils (MSO 1 and 2) and with urea-ammonium nitrate (UAN), ammonium nitrate (AMN), and ammonium sulfate (AMS) fertilizers. Foramsulfuron + iodosulfuron at recommended rate with oil adjuvants reduced biomass of rapeseed plants by 81 (MSO 2) and 84% (MSO 1 and PO). Efficacy of foramsulfuron + iodosulfuron applied at reduced rate was 2 to 9% lower. Addition of MSO 1, MSO 2 or PO to the herbicide applied at reduced rate did not change dynamic surface tension (DST) of the spray solution compared to recommended rate. Methylated rapeseed seed oils (MSO 2) decreased DST more than MSO 1 and PO. Dynamic surface tension of foramsulfuron + iodosulfuron spray mixture with MSO 2 and UAN, AMN or AMS was generally lower than with MSO 1 or PO. The applied adjuvants influenced spray deposit area, but differences were no more than 6 – 12%. The addition of nitrogen fertilizers such as urea (U), ammonium sulfate (AMS) or ammonium nitrate (AMN) maximized nicosulfuron efficacy when applied with petroleum (PO) or pH-buffered methylated seed oil (MSO 2) adjuvants.