The effectiveness of herbicides is affected by the pH of the spray liquid. The use of adjuvants can mitigate the negative effect of pH, and it also allows for a reduction in herbicide doses while maintaining high efficiency. Greenhouse studies were performed to evaluate the efficacy of the herbicide sulcotrione (HRAC F2), against barnyardgrass, at full or reduced doses with adjuvants, and a modified pH of the solutions. The contact angle and surface tension of liquid spray drops, as well as the shear viscosity of individual solutions, were also tested. Results indicated that at a low pH of the spray liquid (4), the use of a reduced dose of sulcotrione with adjuvant based on methylated rapeseed oil can increase the effectiveness of barnyardgrass control to the same level as at the full dose of herbicide. The use of adjuvants contributed to the reduction in the contact angle and the surface tension of liquid spray droplets. No significant differences in shear viscosity were observed for individual solutions.

Weeds in sweet corn reduce the yield and are economically more harmful than other pests. The aim of this study was to evaluate the effects of mechanical weed control and efficacy of pre-and postemergence applied herbicides in sweet corn, and their influence on weed control expressed by various indices, corncob yield and net return. Field studies were carried out with preemergence thiencarbazone-methyl + isoxaflutole (at 29.7 + 74.3 g • ha-1), postemergence S-metolachlor + terbuthylazine (937.5 + 562.5 g • ha-1), mesotrione + terbuthylazine (100 + 652 g • ha-1), terbuthylazine + mesotrione + S-metolachlor (656.3 + + 131.3 + 1093.8 g • ha-1), weed free (WF, hand weeding), and mechanical weeding (MW, hoeing) to assess weed control, corncob yield and net return. Variability in potential yield losses was observed between years due to weather conditions at the level of 30 to even 93%. Hand weeding was the most effective, but it is expensive and needs is labour consuming, unlike mechanical weeding which was the cheapest but simultaneously the least effective. Among pre-and postemergence applied herbicides, a mixture of terbuthylazine + mesotrione + S-metolachlor was the most efficacious weed control treatment. It gave high corncob yield and economic net return.

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.

Due to the steadily increasing cost of weed control in corn (Zea mays L.) and possible negative impact of chemicals on environment the demand for less and more efficient herbicide use is rising. Field studies were carried out in 2010 and 2011 in the Middle-West Poland in order to assessment the effective weed control. Treatments included herbicides tembotrione and flufenacet + isoxaflutole at recommended (88.0 and 36.0 + 7.5 g ha-1) and reduced rates (44 and 22 g ha-1; 19.2 + 4.0 or 9.6 + 2.0 g ha-1) with addition of methylated seed oil (MSO) and ammonium nitrate (AMN) adjuvants. Tembotrione was applied once at the stage of 3-5 maize leaves and flufenacet + isoxaflutole once at pre-emergence of maize. Mixtures of these herbicides were applied sequentially post-emergence, at 16-20-d intervals, after successive weed emergence. Results indicate that herbicide applied at reduced rates with adjuvants provided satisfactory weed control in maize. Application of reduced rates of tembotrione (44 and 22 g ha-1) and especially mixture of tembotrione with flufenacet + isoxaflutole and MSO + AMN adjuvants applied twice provided similar grain yield of maize as from treatments where tembotrione or flufenacet + isoxaflutole herbicides were applied only once at recommended rates (9.5, 9.7, and 10.0 t ha-1, respectively).

A field experiment was carried out in 2019–2021. The effect of an increased amount of iron in water and the addition of citric acid on the efficacy of herbicides applied in maize cultivation at various times was tested. In the pre-emergence treatment, thiencarbazone-methyl + isoxaflutole were applied, while in the post-emergence treatment, nicosulfuron + tritosulfuron + dicamba were applied once in a full dose or in low dose system at two times in half of the recommended dose with the addition of an adjuvant. In selected combinations, FeSO₄ × 7H₂O and citric acid were added to the composition of the spray solution. The species composition of weeds and the efficacy of the herbicides used were determined. Plant stress caused by competition from weeds was investigated by measuring the plant chlorophyll fluorescence. The height of the cultivated plants and their yield level were also determined. The lowest efficacy of weed control was observed when the post-emergence herbicides were applied once. Increasing the iron content in water reduced the efficacy of the herbicides, but the addition of citric acid made it possible to decrease this problem.