Seletividade e eficácia de programas de controle químico de plantas daninhas em soja tolerante e não tolerante a sulfoniluréias

Abstract

The objective of this study was to evaluate the selectivity and effectiveness of chemical weed control programs in soybean lines with and without STS® technology (LCO 44 and LCO 70, respectively). For that, two experiments were carried out in the experimental area of EMBRAPA Agrossilvipastoril in a randomized block design with 10 treatments and 4 replications. The treatments included the application (g ha-1 ) of s-metolachlor (1,152) in pre emergence and combinations with latifolicides at the V4 stage of the culture:chlorimuron-ethyl (20); chlorimuron-ethyl + bentazon (20 + 720), chlorimuron-ethyl+ cloransulam-methyl (20 + 39.23), chlorimuron-ethyl + flumiclorac-pentyl (20 + 60),chlorimuron-ethyl + fomesafen (20 + 250), chlorimuron-ethyl + imazethapyr (20 + 100) and chlorimuron-ethyl + lactofen (20 + 180), and infested and weeded controls. Phytotoxicity, canopy closure and control of Ipomoea grandifolia and Alternanthera tenella (0 to 100%) were evaluated at 7, 14 and 21 days after application, in addition to agronomic characteristics: height of first pod and plant insertion, stand, number of pods per plant and grains per pod, mass of one thousand grains and productivity. Data were submitted to ANOVA following the Scott-Knott test (p<0.05). For the STS® strain, the herbicidetreatments obtained the same yield as the weeded control, except for the infested control and the combination of s-metolachlor with chlorimuron-ethyl + imazethapyr. For the LCO 70 strain, none of the treatments reduced productivity. It was concluded that for the two lines, all treatments were selective, except for the management program with chlorimuron-ethyl + imazethapyr for the STS® line.