Response of sweet maize (Zea mays L.) hybrids to halosulfuron

Limited information exists on the tolerance of sweet maize hybrids to halosulfuron applied post-emergence. The tolerance of eight sweet maize hybrids GG446, GG214, GH2547, GH2041, GH2298, Empire, GH2684, and GSS9299 to halosulfuron applied post-emergence at 25 and 50 g ai ha−1 was evaluated at two Ontario locations in 2005 and 2006. At 7 days after treatment (DAT), Empire and GH2684 hybrids had 4% visible injury at 25 g ai ha−1, and Empire, GH2684, and GH2298 hybrids had 6-8% visible injury at 50 g ai ha−1. There was no injury in the other hybrids. At 14 DAT, there was no visible injury at 25 g ai ha−1 in any of the hybrids evaluated but there was 2-6% visual injury at 50 g ai ha−1 in GH2041, GH2298, Empire, GH2684, and GS9299 hybrids. The injury to all hybrids was transient, with no significant injury observed at 28 DAT. Visible injury tended to increase as herbicide dose increased. There were no adverse effects on plant height, cob size, and marketable yield for any hybrids except the yield of Empire, which was reduced 14% at 25 g ai ha−1 and 21% at 50 g ai ha−1. Based on this study, halosulfuron can be safely applied to GG446, GG214, GH2547, GH2041, GH2298, GH2684, and GSS9299 hybrids, but should not be registered for use on the sweet maize hybrid Empire.