SELECTIVITY OF HERBICIDES APPLIED IN POST-EMERGENCE OF SHOWY CROTALARIA

ABSTRACT Weed control is essential to reduce or eliminate the interference of weeds on crops. Chemical control with the application of herbicides consists of the most used method, with this aim in grain producing areas. Information about the selectivity of herbicides to C. spectabilis (showy crotalaria) are scarce, which are critical for the management of this species as a crop. One field experiment was performed to evaluate the selectivity of herbicides applied in post-emergence of showy crotalaria. The herbicides bentazon (720 and 576 g ha-1), imazethapyr (106 and 79.5 g ha-1), pyrithiobac-sodium (84 g ha-1), flumiclorac (60 g ha-1), flumiclorac in sequential application (30 / 30 g ha-1), imazethapyr + bentazon (106 + 480 g ha-1), and clethodim + quizalofop (96 + 100 g ha-1) were applied in plants with four true leaves, also using a control without herbicide application. Pyrithiobac-sodium and flumiclorac isolated and the tankmix of imazethapyr + bentazon provided greater injuries to showy crotalaria, also affecting the final plant height. Pyrithiobac-sodium (84 g ha-1) was not selective to showy crotalaria. The herbicides imazethapyr (79.5 g ha-1), flumiclorac (sequential application), and bentazon (576 g ha-1), despite the association between clethodim + quizalofop, can be used for weed management in showy crotalaria crop.

摘要
杂草防控对于降低乃至消除杂草对农作物的干扰至关重要。在粮食种植区域，通过施用除草剂开展化学防控是当前最常用的防控手段。目前关于除草剂对美丽猪屎豆（showy crotalaria，C. spectabilis）的选择性相关研究较为匮乏，而该类信息对于将美丽猪屎豆作为经济作物进行田间管理具有关键意义。本研究开展1项田间试验，旨在评估除草剂在美丽猪屎豆出苗后施用时的选择性。供试除草剂包括：苯达松（bentazon，720 g·ha⁻¹与576 g·ha⁻¹）、咪唑乙烟酸（imazethapyr，106 g·ha⁻¹与79.5 g·ha⁻¹）、吡硫氰钠（pyrithiobac-sodium，84 g·ha⁻¹）、氟烯草酸（flumiclorac，60 g·ha⁻¹）、分次施药的氟烯草酸（30/30 g·ha⁻¹）、咪唑乙烟酸+苯达松桶混剂（106+480 g·ha⁻¹），以及烯草酮+精喹禾灵（clethodim + quizalofop，96+100 g·ha⁻¹）；试验设置不施用除草剂的空白对照组。所有供试药剂均在美丽猪屎豆长出4片真叶时喷施。
单独施用吡硫氰钠与氟烯草酸，以及咪唑乙烟酸与苯达松的桶混剂，均会对美丽猪屎豆造成更严重的药害，同时还会影响植株的最终株高。剂量为84 g·ha⁻¹的吡硫氰钠对美丽猪屎豆不具备选择性。剂量为79.5 g·ha⁻¹的咪唑乙烟酸、分次施药的氟烯草酸、576 g·ha⁻¹的苯达松，连同烯草酮与精喹禾灵的组合药剂，均可用于美丽猪屎豆种植田的杂草管理。