## 2 Materials and Methods  
Field study and laboratory analysis of physical and chemical properties of spray liquid droplets were carried out at the Research and Education Center Gorzyn, unit Zlotniki (REC Zlotniki, 52 deg486' N; 16 deg819' E), Poznan University of Life Sciences, Poland, in the years 2017-2019. To plant sugar beet, a Monosem driller was used. The field experiment conditions are presented in Table 1. Field studies were carried out under natural conditions without any artificial irrigation.  
The tested adjuvarts based on rapeseed oil methyl esters, and standard adjuvarts with mixture of phenmedipham with ethofumesate and metamitron were used at recommended and reduced rates (Table 2). Herbicides with and without adjuvarts were applied 3 times, each time after weed emergence (weed at BBCH 11-12), independent of sugar beet plant growth stage during application.  
\begin{table}
\begin{tabular}{l c c c} \hline \hline  & **2017** & **2018** & **2019** \\ \hline Field experiment & \multicolumn{3}{c}{the randomized complete block design} \\ \hline Replications & \multicolumn{3}{c}{4} \\ \hline Plot size, m (area) & \multicolumn{3}{c}{2.7 \(\times\) 10 m (27 m\({}^{-2}\))} \\ \hline Previous crop & winter barley & winter barley & winter trtiticale \\ \hline Sugar beet variety & Gellert & Piast & Piast \\ \hline Planting date & 20 April & 13 April & 9 April \\ \hline Planting density, no. ha\({}^{-1}\) & \multicolumn{3}{c}{120,000} \\ \hline Row space & \multicolumn{3}{c}{45 cm} \\ \hline Planting depth, cm & \multicolumn{3}{c}{2.5} \\ \hline Type of soil and soil composition, \% & \multicolumn{3}{c}{loamy sand} \\ sand & 64 & 64 & 64 \\ clay & 14 & 15 & 15 \\ silt & 26 & 21 & 21 \\ \hline Organic matter, \% & 1.4 & 1.7 & 1.7 \\ \hline pH & 6.8 & 7.3 & 7.2 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Field experiment description, REC Zlotniki 2017–2019.  
A wheelbarrow with a CO\({}_{2}\)-pressurized sprayer equipped with 250 cm boom with five Tejet 11003 vs. nozzle tips spaced 0.5 m apart delivered 200 L ha\({}^{-1}\) of spray liquid. The application pressure was 0.3 MPa, and the ground speed was 1.67 m s\({}^{-1}\). Four weeks after the last herbicide application, weeds from the plots were collected (two randomly selected places in each plot). Weeds were divided into species, weighed, and, using the Henderson-Tilton formula, weed control efficacy was calculated [14].  
The laboratory study included assessment of the physical and chemical properties, both of the water and spray liquid containing herbicides and adjuvants. To measure the pH and electrolytic conductivity (EC) of liquids, an Elemtron pH conductor CPC-505 equipped with an EPS-1 electrode was used. To estimate ST (surface tension) and CA (contact angle) of droplets, an optical tensiometer KSV (Theta Lite) was used. An integral part of the tensiometer was a camera capable of taking up to 60 photos per second, one every 16 ms. The air temperature and relative humidity during surveys were 20-22 \({}^{\circ}\)C and 55-60%, respectively.  
To analyze the recorded data, Statistic software, version 13 (StatSoft Polska Ltd., Krakow, Poland) was used. Before analysis, the raw data were checked for normal distribution of residuals and homogeneity of variance. If necessary, they were transformed to arc sine square root. Finally, back-transformed data in their original unit are presented. To determine significant differences between treatments, an ANOVA (analysis of variance) was performed. [PERSON]'s HSD test at \(p\) = 0.05 to separate means was used. Data from untreated checks were not included in weed control analysis. Relationships between variables pH, ST, CA, and efficacy using correlation coefficients were estimated to present correlated characters (positively or negatively) with spray liquid properties and herbicide efficacy.