Effect of Multifunctional Adjuvants on Physical and Chemical Features of Spray Liquid and Efficacy in Sugar Beet

In the period 2017–2019, field experiments were conducted at the Research and Education Center Gorzyń, unit Złotniki (52°486′ N; 16°819′ E), Poznan University of Life Sciences, at the Luvisols, under natural weather conditions, to evaluate the effect of multifunctional methylated seed oil (EXP 1, 2, and 3) and standard adjuvants (AtB and S) on the efficacy of mixtures phenmedipham + ethofumesate and metamitron applied in full (PEM 1) and reduced rates (PEM 2) in sugar beet. Field studies were carried out and three applications of herbicides were administrated subsequent to the emergence of weeds (BBCH 11–12). PEM applied at reduced rates with EXP was more effective than after AtB and S adjuvants. They enabled the attainment of high and consistent efficacy of herbicides (with EXP—96–97%, AtB—97%, S—95%, compared to PEM 1—93%, and PEM 2—82%), irrespective of varying weather conditions during, and subsequent to, their application. The sugar beet root yield from herbicide treatments after tested adjuvants was higher than from the untreated control and after application of reduced rates of herbicides without adjuvants.