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

Objective: To evaluate the effect of paraffin oil and a mixture of oil-soluble surfactants (APMT) and vegetable oil plus polyalkylene oxide siloxane (ASOP) as adjuvants to potentiate herbicides for the control of Melochia nodiflora and Cynodon sp. in corn crops. Design/methodology/approach: Synthetic chemical herbicides and a bioherbicide were used, with three replicates, at doses of 50 and 100 %, with or without one of the two adjuvants under study. The design was a randomized complete block with a factorial arrangement, where: A (herbicides) had seven levels, B (adjuvants) had four levels and C (evaluation dates) had eight levels, each block consisted of an area of ​​12 m2. The evaluation was carried out every week using the scale proposed by the EWRS. The results were handled in terms of percentage and a data adjustment was performed using the arcsine. A 3-factor factor analysis (AxBxC) and a comparison of means test with Tukey (α ≤ 0.05) were performed using SAS software. Results: In factor A, the greatest control effects corresponded to glyphosate, BH2 (bioherbicide), and dicamba + atrazine, with an average of 77.93, 66.30, and 54.91%, respectively. In factor B, the highest results were obtained with 50% doses of the herbicides plus adjuvants, mainly with APMT and then ASOP with 55.85 and 43.20% control, respectively. For factor C, the treatments showed their greatest effectiveness during the third evaluation, 21 days after application. Limitations on study/implications: The study reveals the opportunity to improve the control of the weeds under study in corn crops, and to seek alternatives to the use of glyphosate. Findings/conclusions: The use of paraffin oil and a mixture of oil-soluble surfactants improved the effect of herbicides (at a dose of 50%) for weed control, such as: ammonium glufosinate, dicamba + atrazine, carfentrazone ethyl and glyphosate; where it stood out when using dicamba + atrazine, instead the use of vegetable oil plus polyalkylene oxide siloxane improved the effect of 2,4-D + carfentrazone ethyl and BH2.