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Effect of Coapplied Glyphosate, Pyrithiobac, Pendimethalin, or S-Metolachlor on Cotton Injury, Growth, and Yield

  • Daniel O. Stephenson (a1), Jason A. Bond (a2), Randall L. Landry (a1) and H. Matthew Edwards (a2)


Field studies were conducted in Louisiana and Mississippi in 2009 and 2010 to evaluate coapplications of glyphosate, pyrithiobac, and residual herbicides on growth and yield of glyphosate-resistant cotton. Treatments were a factorial arrangement of glyphosate (0 and 860 g ae ha−1), pyrithiobac (0 and 470 g ai ha−1), and two residual herbicides (pendimethalin [1,120 g ai ha−1], S-metolachlor [1,070 g ai ha−1], and no residual herbicide). Cotton injury was greatest 3 d after treatment (DAT) and decreased at each evaluation interval until 28 DAT when pyrithiobac was coapplied with glyphosate. Cotton injury ranged from 4 to 17% through 14 DAT when pyrithiobac was applied alone (no residual herbicide) or with pendimethalin, but injury decreased to ≤ 3% after 14 DAT. Cotton injury 3 to 21 DAT following pyrithiobac plus S-metolachlor ranged from 4 to 31%, but S-metolachlor alone injured cotton 1 to 7%. When pyrithiobac was included, cotton injury following S-metolachlor was 3 to 15% greater than that following pendimethalin from 3 to 14 DAT. Pendimethalin did not reduce plant height at 21 or 42 DAT compared with treatments receiving no residual herbicide, but S-metolachlor reduced plant heights 5 and 4% at 21 and 42 DAT, respectively. Although cotton injury was severe in some cases and persisted until 21 DAT, the injury did not cause reductions in yield. This indicates the early-season cotton injury was transient, and cotton was able to recover from the injury with no observed differences in yield.

En 2009 y 2010, se realizaron estudios de campo en Louisiana y Mississippi para evaluar el efecto de co-aplicaciones de glyphosate, pyrithiobac, y herbicidas residuales sobre el crecimiento y el rendimiento del algodón con resistencia a glyphosate. Los tratamientos estuvieron en un arreglo factorial de glyphosate (0 y 860 g ae ha−1), pyrithiobac (0 y 470 g ai ha−1), y tres herbicidas residuales (pendimethalin [1,120 g ai ha−1], S-metolachlor [1,070 g ai ha−1], y sin herbicida residual). Cuando pyrithiobac fue co-aplicado con glyphosate, el mayor daño en el algodón se dio 3 días después del tratamiento (DAT) y se redujo en cada intervalo de evaluación hasta 28 DAT. Cuando se aplicó pyrithiobac solo (sin herbicida residual) o con pendimethalin, el daño en el algodón varió de 4 a 17% hasta 14 DAT, pero el daño disminuyó a ≤3% después de 14 DAT. El daño en el algodón a 3 a 21 DAT, después de la aplicación de pyrithiobac más S-metolachlor varió de 4 a 31%, pero S-metolachlor solo dañó el algodón de 1 a 7%. Cuando se incluyó pyrithiobac, el daño en el algodón después de S-metolachlor fue 3 a 15% mayor que después de pendimethalin de 2 a14 DAT. Pendimethalin no redujo la altura de las plantas a 21 ó 42 DAT al compararse con tratamientos sin herbicida residual, pero S-metolachlor redujo la altura de las plantas 5 a 4% a 21 y 42 DAT, respectivamente. Aunque el daño en el algodón fue severo en algunos casos y persistió hasta 21 DAT, el daño no causó reducciones en el rendimiento. Esto indica que el daño en el algodón temprano en la temporada de crecimiento fue transitorio, y que el algodón fue capaz de recuperarse y no mostrar diferencias en el rendimiento.


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Effect of Coapplied Glyphosate, Pyrithiobac, Pendimethalin, or S-Metolachlor on Cotton Injury, Growth, and Yield

  • Daniel O. Stephenson (a1), Jason A. Bond (a2), Randall L. Landry (a1) and H. Matthew Edwards (a2)


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