The aim of the study was to determine the level of biological effectiveness of soybean protection systems and to rationally combine the mechanisms of action of herbicidal formulations with the use of the adjuvant Skaba EC. The effectiveness of herbicide active substances on weed infestation and soybean yield was evaluated. The index of competitive pressure of weeds on crops was determined. Under all studied conditions, a clear hierarchy of effectiveness between two- and three-component systems was observed. Differences between application rates were much less pronounced than expected. When using 100% herbicide rates in combination with the adjuvant Skaba EC (0.2 L/ha) in two-component systems, the average reduction in weed numbers was: for annual broadleaf weeds – 80.0-91.4%, for annual grasses – 72.0-92.0%, and for perennial broadleaf weeds – 69.0-81.0%. In the three-component system, these values were 95.1%, 94.0%, and 87.0%, respectively. Reducing the herbicide rate to 75% combined with an increased adjuvant rate (0.3 L/ha) did not result in a significant decrease in weed control effectiveness. In the three-component system, the values reached 93.9%, 94.5%, and 85.0%, respectively. A 25% reduction in herbicide rates, when combined with the adjuvant, had little effect on the final biological outcome, while significantly reducing the chemical load on the agroecosystem. The combination of inhibitors provided the highest biological effectiveness of weed control. The level of weed infestation in soybean crops during the years of study depended significantly on the composition of the herbicide protection system and the combination of products with different mechanisms of action of active substances on plants. Two-component systems without the use of an adjuvant ensured moderate weed reduction (58-88%), whereas three-component multisite combinations increased control effectiveness to 85-97% for annual species and 76-88% for perennial species (and under conditions with an adjuvant – up to 90-97% and 84-88%, respectively). When applying optimised (reduced by 3-40%) herbicide rates in combination with the maximum adjuvant rate (0.4 L/ha), weed control efficiency remained consistently high
Sykalo et al. (Tue,) studied this question.