Effect of Adjuvants in Herbicides for Weed Control in Maize (Zea mays L.) Cultivation

Resumen

Objective: This study aimed to evaluate the effect of paraffin oil combined with a mixture of oil-soluble surfactants (APMT) and vegetable oil plus polyalkylene oxide siloxane (ASOP) as adjuvants to enhance the efficacy of herbicides for the control of Melochia nodiflora and Cynodon species in maize (Zea mays L.) crop.

Design/Methodology/Approach: The experiment involved the use of synthetic chemical herbicides and a bioherbicide, applied at two dosage levels (50% and 100%), with or without the inclusion of either of the two adjuvants under evaluation. The experimental design was a randomized complete block with a factorial arrangement: factor A (herbicides) included seven levels, factor B (adjuvants) comprised four levels, and factor C (evaluation dates) involved eight levels. Each block covered an area of 12 m². Weed control effectiveness was assessed weekly using the scale proposed by the European Weed Research Society (EWRS). Data were expressed as percentages and subjected to arcsine transformation for statistical analysis. A three-way factorial ANOVA (AxBxC) and Tukey’s mean comparison test (α ≤ 0.05) were conducted using SAS software.

Results: In factor A, the highest weed control effectiveness was observed with glyphosate, BH2 (bioherbicide), and dicamba + atrazine, achieving average control rates of 77.93%, 66.30%, and 54.91%, respectively. For factor B, the highest control rates were obtained with 50% herbicide doses combined with adjuvants, particularly APMT (55.85%) followed by ASOP (43.20%). Regarding factor C, the treatments exhibited their peak effectiveness during the third evaluation, conducted 21 days after application.

Limitations/Implications: The findings highlight the potential to improve the control of the studied weed species in maize crop and underscore the need to explore alternatives to glyphosate use.

Findings/Conclusions: The application of paraffin oil and a mixture of oil-soluble surfactants significantly enhanced the efficacy of herbicides, especially at the 50% dosage, for controlling weeds such as ammonium glufosinate, dicamba + atrazine, carfentrazone ethyl, and glyphosate. Notably, the combination with dicamba + atrazine showed the greatest improvement. Additionally, the use of vegetable oil plus polyalkylene oxide siloxane was particularly effective in enhancing the performance of 2,4-D + carfentrazone ethyl and BH2.