Efficacy of herbicides in postemergence control of weeds in corn crop

O objetivo do trabalho foi avaliar a eficácia agronômica de herbicidas aplicados no controle em pós-emergência de plantas daninhas e avaliar a seletividade à cultura do milho. O experimento foi desenvolvido no período de dezembro/OO a abril/Ol, na FEP-UNESP, em Selvíria, MS. O experimento foi conduzido em cultivo convencional e o híbrido de milho utilizado foi o 'Master '. O delineamento experimental adotado foi o de blocos ao acaso, com 9 tratamentos e 4 repetições. Os tratamentos avaliados foram: foramsulfuron (35,0 e 45,5 g/ha), foramsulfuronliodosulfuron-methyl-sodium (36,0/2,4 e 45,0+3,0 g/ha), nicosulfuron (50,0 g/ha), foramsulfuron--atrazine, (35,0+ 1000,0 e 45,0+ 1000,0 g/ha) e testemunhas no mato e no limpo. As aplicações foram realizadas com um pulverizador costal a pressão constante (CO)-de 3,2 kg/crrr', com barra equipada com quatro bicos do tipo leque, Teejet 110.03 XR, espaçados de 0,5 m e consumo de calda de 250 l/ha. Os tratamentos herbicidas foram seletivos à cultura de milho. Os tratamentos foramsulfuron (45,5 g/ha), foramsulfuron/ iodosulfuron-methyl-sodium (36,0/2,4 e 45,0/3,0 g/ha) e foramsulfuron+atrazine (45,0+1000,0 g/ha) foram eficazes no controle de Bidens pilosa, Commelina benghalensis e Digitaria horizonialis. Os tratamentos foramsulfuron (35,0 g/ha), nicosulfuron (50,0 g/ha) e foramsulfuroru-atrazine (35,0+ 1000,0 g/ha) foram eficazes no controle de B. pilosa e C. benghalensis. Não foi observado efeito fitotóxico dos herbicidas ao milho.The objective of this research was to evaluate the agronomic efficiency of herbicides applied as a postemergence treatment on the control of weeds and to evaluate the tolerance of the treatments for com. The experiment was developed during the period from december/OO to april/O 1, at FEP-UNESP at Selvíria, Mato Grosso do Sul, Brasil. The experiment was carried out in a conventional system and the hybrid com used was 'Master ' at a spacing of 0.9 m between rows with 5.4 seeds per meter. The experimental design was a randomized complete block, with 9 treatments and 4 replicates with 5 !ines of the crop. Plot size was 4.5 x 5.0 m. The treatments were: foramsulfuron (35.0 and 45.5 g/ha), foramsulfuronliodosulfuronmethyl- sodium (36.0/2.4 and 45.0/3.0 g/ha), nicosulfuron (50.0 g/ha), foramsulfuron- atrazine (35.0+1000.0 and 45.0+1000.0 g/ha) and a weed-free and a weeded control. The applications were accomplished with a manual sprayer and constant pressure (COz) of 45 lb/pol-, equipped with four Teejet 110.03 XR nozzles, spaced at 0.5 m and volume of 250 I/ha. The treatments were selective for the crop. The treatments foramsulfuron (45.5 g/ha), foramsulfuronliodosulfuron-methyl-sodium (36.0/2.4 and 45.0/3.0 g/ha) and foramsulfuroru-atrazine (45.0+1000.0 g/ha) were efficient in the control of Bidens pilosa, Commelina benghalensis and Digitaria horizontalis. The treatments foramsulfuron (35.0 g/ha), nicosulfuron (50.0 g/ ha) and forarnsulfuron+atrazine (35.0+ 1000.0 g/ha) were efficient in the control of B. pilosa and C. benghalensis.