Submitted to: Agronomy Abstracts
Publication Type: Abstract only
Publication Acceptance Date: 11/8/1996
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Nicosulfuron is labeled for application on corn up to 50 cm tall. Spraying at this late stage can decrease grain yield in early-maturing hybrids. Herbicide damage is manifest as a decrease in row number per ear. We are testing whether ear malformation results from herbicide application during ear differentiation. Eight hybrids varying from 80 to 110 day Minnesota relative maturity rating (RM) were planted at Morris and Lamberton, Minnesota in 1995 and sprayed with nicosulfuron at the labeled rate when plants were either 10, 25, or 50 cm tall. Plants were sampled at spraying, anthesis, and harvest to quantify stage of apical ear development, potential kernel number, and final kernel number per ear. Nicosulfuron application decreased potential kernel number by as much as 35% compared to untreated controls. No ear damage was evident when plants were treated at 10 cm, which was prior to ear initiation in all hybrids. Ears on plants treated at 25 cm had more damage than those treated at 50 cm, but more ear were affected in the later treatment. Thus, the extent of ear malformation was correlated with the stage of ear development when plants were sprayed. Grain yield decreased about 0.3 Mg ha**-1 (out of about 10 Mg ha**-1) in treatments having the most severely malformed ears (80 RM, 50 cm). Poor correspondence between potential kernel loss and yield loss reflected the lack of apical kernel development on untreated ears and modest compensation in kernel size on damaged ears.