Effects of adjuvants and carriers on propoxycarbazone and pyroxsulam efficacy on Bromus sterilis in winter wheat

Abstract

Bromus species are annual winter weeds from the Poaceae family which have become troublesome weeds of winter cereals. The herbicides propoxycarbazone and pyroxsulam are widely used for control of B. sterilis. The objective of this study was to determine the effect of different types of adjuvants and carriers on the efficacy of pyroxsulam and propoxycarbazone on B. sterilis. Small plot field trials were carried out in North Bohemia, Central Europe during 2011-2013. The tested carriers and adjuvants affected the efficacy of both herbicides and the seed production of B. sterilis. Urea ammonium nitrate was a less effective carrier than water (differences 5-30%). The most effective adjuvant was methylated seed oil (MSO), whose addition into the application water solution increased the herbicide efficacy of propoxycarbazone by 5-35%. Efficacy of the herbicide pyroxsulam was increased by adjuvant MSO by 10-30%. Nonionic surfactant increased herbicide efficacy only in 2013 (by 17%). Effect of organosilicone surfactant on the herbicide efficacy was negative (lower efficacy). Seed production of B. sterilis on untreated plots ranged between 20 000 and 50 000 seeds/m2 in experimental years. Seed production was the lowest on plots treated by the herbicide plus MSO (1300-4500 seed/m2).

Keywords

• spring appliaction of herbicide
• urea ammonium nitrate
• heptamethyltrisiloxane
• isodecyl alcohol ethoxylate
• methyl ester of rapeseed oil