Efeito residual de herbicidas auxínicos em nitossolo e ação sobre plantas daninhas

Abstract

Auxinic herbicides are considered very useful tools for weed management in pre-planting desiccation procedures prior crop species, and are critical for controlling glyphosate-tolerant species. The duration of herbicide activity in the straw-soil system to control species in the seed bank has not yet been investigated. This study was undertaken to determine the residual effect of these herbicides in the soil, the effect of straw on herbicide retention and availability in the soil, and to rank the weed species most susceptible to the herbicides. The effect of five auxin herbicides (2,4 - D, Dicamba, Triclopyr, Halauxifen-methyl and Florpirauxifen - benzyl) applied pre-emergence, on 3 weed species (Euphorbia heterophylla, Commelina benghalensis and Amaranthus hybridus) was evaluated. relative tolerance level was evaluated at 21 and 28 days after emergence and determination of aboveground biomass at 28 days. The bioassays show that, in general, there was variation in the residual effect between herbicides and the weed species evaluated, being directly related to the characteristics of the herbicides and the weed species. For the species Commelina benghalensis and Amaranthus hybridus the herbicides that were most effective and showed a long residual effect were dicamba and triclopyr. For Euphorbia heterophylla, the herbicides dicamba, halauxifen and florpyrauxifen had the highest control efficacy at all application times, with a long residual effect. And the herbicide 2,4-D was the one with the lowest residual efficacy and control in all weeds evaluated.