Giant ragweed (Ambrosia trifidaL.) control in corn

Abstract

Soltani, N., Shropshire, C. and Sikkema, P. H. 2011. Giant ragweed (Ambrosia trifidaL.) control in corn. Can. J. Plant Sci. 91: 577–581. Twelve field trials (five with PRE and seven with POST herbicides) were conducted over a 4-yr period (2006–2009) on various Ontario farms with heavy giant ragweed infestations (22 plants m–2) to determine the effectiveness of preemergence (PRE) and postemergence (POST) herbicides for the control of giant ragweed in corn. Atrazine, dicamba, dicamba/atrazine, isoxaflutole plus atrazine, mesotrione plus atrazine, saflufenacil, and saflufenacil/dimethenamid applied PRE provided 9–52, 60–80, 64–83, 44–77, 33–80, 36–80, and 43–63% control of giant ragweed, reduced giant ragweed density 55, 45, 59, 64, 68, 73, and 77% and reduced giant ragweed shoot dry weight 60, 89, 90, 87, 83, 81, and 78%, respectively. Atrazine, dicamba, dicamba/diflufenzopyr, dicamba/atrazine, 2,4-D/atrazine, bromoxynil plus atrazine, prosulfuron plus dicamba, primisulfuron/dicamba, mesotrione plus atrazine, topramezone plus atrazine, and bentazon/atrazine applied POST provided 46–94, 70–90, 69–84, 82–94, 56–83, 59–76, 66–84, 71–81, 49–81, 34–78, and 26–84% control of giant ragweed, reduced giant ragweed density by 65, 82, 71, 82, 76, 76, 59, 65, 59, 47, and 71% and reduced giant ragweed shoot dry weight by 97, 99, 97, 99.6, 98, 98, 95, 97, 95, 88, and 96%, respectively. Based on these results, dicamba/atrazine provided the best and most consistent control of giant ragweed in corn of the PRE and POST herbicides evaluated.