Aplicações sequenciais ou associações? qual a melhor escolha para os herbicidas inibidores da ACCase e latifolicidas em dessecação pré-semeadura de Conyza spp (L.) Conquist e Digitaria insularis (L.) Fedde

Abstract

The Mato Grosso do Sul’s region is highlighted in agricultural production, for the obtainment of high productive level, the weed’s management is essential. Among the weed species, Conyza spp. L. (hairyfleabane) and Digitaria insularis L. (sourgrass) stand out as hard control species, due to its presence of resistant biotypes to different herbicides and/or mechanisms of action. The objective of this work was to evaluate which was the best control management in areas infested with Conyza spp. and Digitaria insularis in pre-sowing desiccation in weeds with high developed phenological stage. For which, it was done a field experiment at federal university of the Great Dourados - UFGD’s experimental farm – Dourados/MS, in experimental delineation of casualized blocks, with 4 repetitions for each treatment, 13 treatments: (1) 2,4 D + glyphosate (1000+1440 g.a.i.ha-1 ); (2) dicamba + glyphosate (480+1440 g.a.i.ha-1 ); (3) fluroxypyr/clethodim + glyphosate (300+210+1440 g.a.i.ha-1 ); (4) triclopyr + glyphosate (720+1440 g.a.i.ha-1 ); (5) atrazine/mesotrione + glyphosate (500+50+1440 g.a.i.ha-1 ); (6) diclosulam/halauxifen-methyl + glyphosate (20,3+3,86+1440 g.a.i.ha-1 ); (7) 2,4-D + glyphosate + haloxifop-p-methyl (1000 + 1440+150 g.a.i.ha-1 ); (8) dicamba + glyphosate+ haloxifop-p-methyl (480+1440+150 g.a.i.ha- ¹); (9) triclopyr + glyphosate + haloxifop-p-methyl (720+14400+150 g.a.i.ha-1 ); (10) atrazine/mesotrione + glyphosate + haloxifop-p-methyl (500+50+1440+150 g.a.i.ha-1 ); (11) diclosulam/halauxifen-methyl + glyphosate + haloxifop-p-methyl (20,3+3,86+1440+150 g.a.i.ha1 ); (12) atrazine/mesotrione + 2,4-D (500+50+1000 g.a.i.ha-1 ); (13) atrazine/mesotrione + 2,4-D + haloxifop-p-methyl (500+50+1000+150 g.a.i.ha-1 ); and a witness for comparison. The treatments 1, 2, 4, 5, 6, 12 received dose of haloxyfop-p-methyl (150 g.i.a.ha-1 ) 10 days after the initial application and dose of ammonium glufosinate 20 days after the initial application (400 g.i.a.ha1 ); the treatments 3, 7, 8, 9, 10, 11, 13 received dose of ammonium glufosinate (400 g.i.a.ha-1 ) 10 days after the initial application. The visual analysis data were submitted to deviance’s analyze utilizing the additive models generalized to location, scale and form (GAMLSS), with Beta’s distribution for the variables of Conyza spp and Digitaria insularis control. The auxinics 2,4-D, dicamba and triclopyr were the ones that most affected the haloxyfop-p-methyl efficacy with average control inferior to 80% for Digitaria insularis in all reviews, the association diclosulan/halauxifen-methyl didn’t affected negatively the control of Digitaria insularis when associated or in sequential with haloxyfop-p-methyl presenting control superior to 80% at 35 DAT. The Conyza spp’s management with fluroxypyr/clethodim and glyphosate + 2,4-D were inferior to 75%, this way, being disadvantaged when compared to the other treatments that reached average control superior to 80%. Therefore, in areas with mixed infestation of broadleaves and narrowleaves, there are options for effective control of both species like diclosulam/halauxifenmethyl associated to haloxyfop-p-methyl and sequentials options of haloxyfop-p-methyl with initial application of the herbicides diclosulam/halauxifen-methyl and atrazine/mesotrione.