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.

To reduce the cost of intensive herbicide application and environment pollution and enhance biological effectiveness, effective multifunction adjuvants should be used. A field study was conducted in 2017–2019 in midwestern Poland in order to assess the effects of new adjuvant formulations on the activity of herbicides. Treatments included the herbicide nicosulfuron at recommended (40 g ha−1) and reduced rates (28 g ha−1) alone and with the addition of tested MSO 1, MSO 2, and MSO 3 (differing in the type and amount of surfactants), as well as standard (MSO 4 and NIS) adjuvants. Nicosulfuron was applied once during the 3–5 leaf stage of maize. Results indicate that nicosulfuron with the tested adjuvants provided satisfactory weed control equivalent to that provided by standard MSO 4 and better than that provided by NIS. Nicosulfuron applied with the tested adjuvants led to a similar grain yield of maize as that achieved with standard adjuvant treatments and much higher than that measured in untreated crops.