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Urea Ammonium Nitrate Effects on Bispyribac and Penoxsulam Efficacy

  • Bree A. Pearson (a1), Robert C. Scott (a1) and V. Frank Carey (a2)


Experiments were conducted at the Lonoke Extension and Applied Research Center greenhouse at Lonoke, AR, to evaluate the effects of urea ammonium nitrate (UAN) on bispyribac and penoxsulam efficacy on barnyardgrass, hemp sesbania, and broadleaf signalgrass. Herbicide treatments included bispyribac at 17.9 or 35.8 g ai/ha or penoxsulam at 24.4 or 48.9 g ai/ha tank mixed with (1) no adjuvant, (2) a nonionic organosilicone (OSL) adjuvant at 0.125% v/v, (3) a methylated seed oil/organosilicone (MSO/OSL) adjuvant at 0.37 L/ha, (4) a proprietary blend of MSO/OSL/UAN at 2% v/v, (5) UAN at 2% v/v, (6) OSL at 0.125% plus UAN at 2% v/v, or (7) MSO/OSL at 0.37 L/ha plus UAN at 2% v/v. In addition to these adjuvants, penoxsulam was also applied with crop oil concentrate (COC) at 2.34 L/ha and with COC at 2.34 L/ha plus UAN at 2% v/v. The addition of UAN to either herbicide plus an adjuvant increased herbicide efficacy on barnyardgrass in the greenhouse, with 95 to 99% biomass reduction of three- to four-leaf barnyardgrass and 88 to 92% biomass reduction of one- to three-tiller barnyardgrass. UAN did not generally increase efficacy on hemp sesbania, as control was 90% or higher with treatments containing either herbicide and a recommended adjuvant. Adding UAN did not increase efficacy on broadleaf signalgrass. Broadleaf signalgrass control was highly variable and no treatment provided more than 65% biomass reduction.


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Dillon, T. W. and Scott, R. C. 2004. Clincher post-flood for grass control in rice. Proc. South. Weed Sci. Soc 57:300.
Dodds, D. M., Reynolds, D. B., Massey, J. H., and Koger, C. H. 2007. Effect of adjuvant and urea ammonium nitrate on bispyribac-sodium efficacy, absorption, and translocation in barnyardgrass (Echinochloa crus-galli). II. Absorption and translocation. Weed Sci 406411.
Dow AgroSciences 2004. Grasp SC Specimen Label. Accessed: February 21, 2006.
Fielding, R. J. and Stoller, E. W. 1990. Effects of additives on efficacy, uptake, and translocation of chlorimuron ethyl ester. Weed Technol 4:264271.
Kendig, J. A., Cobill, R. M., Hinklin, B. A., and Ezell, P. M. 2003. Weed control programs with newer rice herbicides. Proc. South. Weed Sci. Soc 56:4243.
Lassiter, R. B., Langston, V. B., Mann, R. K., Richburg, J. S., and Watson, L. C. 2005. The effectiveness of penoxsulam in water-seeded rice and Clearfield rice systems. Proc. South. Weed Sci. Soc 58:22.
Malik, M. S., Talbert, R. E., Scherder, E. F., Lovelace, M. L., and Ottis, B. V. 2003. Alternative herbicides for the control of quinclorac- and propanil-resistant barnyardgrass. Proc. South. Weed Sci. Soc 56:41.
Meins, K. B., Scott, R. C., and Pearrow, N. D. 2005. Rice tolerance and weed control with penoxsulam herbicide. Proc. South. Weed Sci. Soc 58:13.
Monaco, T. J., Weller, S. C., and Ashton, F. M. 2002. Weed Science. Principles and Practices. 4th ed. New York: Wiley. 146156.
O'Barr, J. H., Chandler, J. M., and McCauley, G. N. 2003. Pre vs. post flood applications of Regiment in rice. Proc. South. Weed Sci. Soc 56:52.
Ottis, B. V., Lassiter, R. B., Malik, M. S., and Talbert, R. E. 2004. Penoxsulam (XDE-638) for rice weed control. Proc. South. Weed Sci. Soc 57:304.
Schmidt, L. A., Talbert, R. E., Baldwin, F. L., Rutledge, J. S., Scherder, E. F., and Wheeler, C. C. 1999. Performance of V-10029 (bispyribac-sodium) in rice weed control programs. Proc. South. Weed Sci. Soc 52:4950.
Thompson, W. M., Nissen, S. J., and Masters, R. A. 1996. Adjuvant effects on imazethapyr, 2,4-D, and picloram absorption by leafy spurge (Euphorbia esula). Weed Sci 44:469475.
Valent USA 2003. Regiment Herbicide Specimen Label. Accessed: February 21, 2006.
Valent USA 2005. Regiment Herbicide: Approved Surfactants for Use With Regiment. Walnut Creek, CA: Valent USA Corp. 6.
Vencill, W. K., editor. 2002. Herbicide Handbook. 8th ed. Lawrence, Kansas: Weed Science Society of America. 51.
Williams, B. J. 1999. Barnyardgrass (Echinochloa crus-galli) control in dry-seeded rice with V-10029. Proc. South. Weed Sci. Soc 52:50.
Williams, B. J. and Burns, A. B. 2006. Penoxsulam a new herbicide for broadleaf weed management in rice. Proc. South. Weed Sci. Soc 59:12.
Williams, B. J., Burns, A. B., and Copes, D. B. 2004. Evaluation of DE-638 in drill-seeded rice. Proc. South. Weed Sci. Soc 57:72.
Young, B. G. and Hart, S. E. 1998. Optimizing foliar activity of isoxaflutole on giant foxtail (Setaria faberi) with various adjuvants. Weed Sci 46:397402.



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