PERFORMANCE OF IMAZETHAPYR-RESISTANT CORN (ZEA-MAYS) COMPARED WITH SUSCEPTIBLE NEAR-ISOGENIC AND COMMERCIAL HYBRIDS

Farmers need information on herbicide technology and crop performance to assess the profitability of new herbicide-resistant crop technologi es. First-generation imazethagyr-resistant corn hybrids evaluated at t he University of Wisconsin yielded less than other commercial hybrids. To determine if this resistance trait affected yield or agronomic tra its, 10 near-isogenic pairs of imazethapyr-resistant and -susceptible corn hybrids were compared. Whether treated with imazethapyr or not, i mazethapyr-resistant hybrids yielded the same when averaged across hyb rids, although yield varied among a few individual hybrids within sing le experiments. Seven of the imazethaypr-resistant hybrids yielded the same, two yield more, and one yielded less than their susceptible nea r-isogenic counterpart during eight site-years. Grain moisture was not affected, but imaaethapyr-resistant hybrids had fewer broken stalks t han 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.