RESPONSE OF CORN TO IMAZETHAPYR SOIL RESIDUES AND SELECTED ALS HERBICIDES

Authors: HULTING, ANDREW - UNIV OF ILLINOIS; SIMMONS, FREDERICK - UNIV OF ILLINOIS; WAX, LOYD

Submitted to: North Central Weed Science Society US Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 1/14/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: There has been concern about the potential of residues of ALS-inhibiting herbicides used in soybean to cause injury to corn planted the next year. To assess this potential, we established field plots at three locations in Illinois. Normal and double use rates of imazethapyr were applied in soybeans, including late in the season, to weedy and weed-free soybeans. Then, the following spring, corn was planted early, and either not treated and kept weed free by hand weeding and cultivation, or was treated with a variety of herbicides, including some ALS-inhibiting herbicides that in theory might be additive to the previously applied ALS inhibitor, and result in greater injury to the corn crop. These studies were conducted for two years at the three locations and weather conditions were closely monitored as well as were the growth, development and yield of the corn crop. Over a variety of environmental conditions, some injury to the crop, slowed growth and development and malformation of the corn ears was observed, but only at some sites and only at the double use rates of the herbicide imazethapyr. ALS herbicides used during the corn year did not appear to be additive with the imazethapyr applied the previous year. Injury was greater where imazethapyr was applied to soybeans with no weed growth compared with soybeans with weed growth - application to plots with more bare soil resulted in greater persistence. However, there were no significant corn yield reductions, compared with the hand-weeded checks, from any of the herbicide treatments.