Eficácia de herbicidas aplicados em pós-emergência na cultura da soja convencional e transgênica Efficacy of herbicides applied in post emergence on conventional and transgenic soybean

• Main Authors: M.J.P Corrêa, P.L.C.A Alves
• Format: Article
• Language: English
• Published: Sociedade Brasileira da Ciência das Plantas Daninhas 2009-12-01
• Series: Planta Daninha
• Subjects: lactofen; fitotoxicidade; Glycine max; glyphosate; phytotoxicity
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582009000500017

Na cultura da soja é frequente o uso de herbicidas seletivos aplicados em pósemergência para o controle das plantas daninhas. Com o objetivo de avaliar a eficiência e a seletividade de herbicidas aplicados em pós-emergência, isolados e em misturas, para o controle de plantas daninhas e os efeitos sobre o crescimento e o desenvolvimento da soja convencional (M-SOY 8001) e transgênica (M-SOY 7908 RR), foram desenvolvidos dois experimentos em campo, nos anos agrícolas 2006/2007 e 2007/2008. Os tratamentos constaram dos herbicidas: lactofen (168 g ha-1), glyphosate (1.080 g ha-1), lactofen + chlorimuronethyl (96 + 10g ha-1), chlorimuron-ethyl + imazethapyr (10 + 70 g ha-1), chlorimuron-ethyl + bentazon (10 + 600 g ha-1), glyphosate + imazethapyr (900 + 70 g ha-1), lactofen + chlorimuronethyl + imazethapyr (96 + 10 + 70 g ha-1) e lactofen + chlorimuron-ethyl + imazethapyr/ haloxyfop-methyl (96 + 10 + 70 + 60 g ha-1). Além disso, mantiveram-se duas testemunhas sem aplicação de herbicida (capinada e sem capina). O delineamento experimental utilizado foi em blocos ao acaso, com quatro repetições. O herbicida lactofen aplicado isoladamente e em mistura com chlorimuron-etyl, imazethapyr e haloxyfop-methyl provocou intoxicação inicial às plantas de soja, porém aos 27 dias após aplicação a cultura apresentava-se recuperada. No primeiro ano agrícola, as plantas daninhas foram satisfatoriamente controladas pelos tratamentos químicos. No segundo ano, os tratamentos que resultaram em melhor controle das infestantes foram glyphosate e glyphosate + imazethapyr. Houve redução na altura final das plantas, no segundo ano, tratadas com chlorimuron-ethyl + imazethapyr, lactofen + chlorimuron-ethyl + imazethapyr e lactofen + chlorimuron-ethyl + imazethapyr/haloxyfopmethyl. Foi constatada redução na produtividade de grãos da variedade M-SOY 7908 RR tratada com lactofen e com a mistura chlorimuron ethyl + bentazon no primeiro ano. A aplicação de chlorimuron-ethyl + bentazon proporcionou redução na produtividade da variedade M-SOY 8001 no segundo ano.<br>The use of selective herbicides is frequent in post emergence of soybean crop for weed control. A field experiment was conducted at the Education, Research and Production Farm of UNESP in Jaboticabal, SP, Brazil, during the growing years 2006/2007 and 2007/2008 to evaluate the efficiency and selectivity of post herbicide application, alone and in mixtures, for weed control, on conventional (M-SOY 8001) and transgenic (M-SOY 7908 RR) soybean growth and development. Treatments consisted of the application of the following herbicides, alone or in mixture: lactofen (168 g ha-1), glyphosate (1080 g ha-1 ), lactofen + chlorimuron-ethyl (96 + 10 gha-1), chlorimuron-ethyl + imazethapyr (10 + 70 g ha-1), chlorimuron-ethyl + bentazon (10 + 600 g ha-1), glyphosate + imazethapyr (900 + 70 g ha-1), lactofen + chlorimuron-ethyl + imazethapyr (96 + 10 + 70 g ha-1) and lactofen + chlorimuron-ethyl + imazethapyr/haloxyfop-methyl (96 + 10 + 70 + 60 g ha-1). The tests included two non-treated controls. A randomized block experimental design was used with four replications. Lactofen applied alone and the mixtures chlorimuron-etyl, imazethapyr and haloxyfopmethyl did not cause initial injury in the soybean plants, but the plants recovered on the 27th day after application. In the first year, the chemical treatments did exert sufficient control over the weeds and in the second year, the glyphosate and glyphosate + imazethapyr treatments presented the best weed control. In the second year, a reduction was observed in the final height of the soybean plants treated with chlorimuron-ethyl + imazethapyr, lactofen + chlorimuron-ethyl + imazethapyr and lactofen + chlorimuron-ethyl + imazethapyr/haloxyfop-methyl. A yield reduction was verified in soybean M-SOY 7908 RR, treated with lactofen alone and with the mixture chlorimuron ethyl + bentazon in the first year. The chlorimuron-ethyl + bentazon treatment provided a reduction in soybean M-SOY 8001 yield in the second year.