Performance of Imazethapyr-Resistant Corn
(Zea mays) Compared with Susceptible
Near-Isogenic and Commercial Hybrids

Chris M. Boerboom and Joe G. Lauer

Farmers need information on herbicide technology and crop performance to assess the profitability of new herbicide-resistant crop technologies. First-generation imazethapyr-resistant corn hybrids evaluated at the University of Wisconsin yielded less than other commercial hybrids. To determine if this resistance trait affected yield or agronomic traits, 10 near-isogenic pairs of imazethapyr-resistant and -susceptible corn hybrids were compared. Whether treated with imazethapyr or not, imazethapyr-resistant hybrids yielded the same when averaged across hybrids, although yield varied among a few individual hybrids within single experiments. Seven of the imazethaypr-resistant hybrids yielded the same, two yield more, and one yielded less than their susceptible near-isogenic counterpart during eight site-years. Grain moisture was not affected, but imazethapyr-resistant hybrids had fewer broken stalks than did susceptible hybrids. The imazethapyr resistance trait does not appear to affect yield potential, but the backcrossing procedure may have caused early resistant hybrids to lag behind in yield compared to other new hybrids.

Weed Technology. 1997. Volume 11:110-117