|LANDAU, CHRISTOPHER - University Of Illinois|
|BERNARDS, MARK - Western Illinois University|
|HAGER, AARON - University Of Illinois|
Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/12/2022
Publication Date: 2/11/2022
Citation: Landau, C.A., Bernards, M.L., Hager, A.G., Williams II, M.M. 2022. Significance of application timing, formulation, and cytochrome P450 genotypic class on sweet corn response to dicamba. Weed Science. 70(2):167-173. https://doi.org/10.1017/wsc.2022.5.
Interpretive Summary: Herbicides are the primary method to control weeds in U.S. corn production; however, corn can be injured by specific herbicides. The herbicide dicamba is being used to a greater extent in recent years in corn as well as other crops. We found that cyprosulfamide, an herbicide safener, reduced risk of corn injury from the dicamba. We also identified when the crop was most susceptible to dicamba, in terms of growth stage and genetic background. These findings arm seed companies, herbicide manufacturers, and growers with new knowledge that will reduce occurrence of corn injury from dicamba.
Technical Abstract: Sweet corn (Zea mays L.) tolerance to dicamba and several other herbicides is due to cytochrome P450 (CYP) mediated metabolism and is conferred by a single gene (Nsf1). Tolerance varies by CYP genotypic class with hybrids homozygous for functional CYP (Nsf1Nsf1) being the most tolerant and hybrids homozygous for mutant CYP alleles (nsf1nsf1) being the least tolerant. The herbicide safener cyprosulfamide (CSA) increases tolerance to dicamba by stimulating the expression of several CYPs. However, the extent to which CSA improves the tolerance of different sweet corn CYP genotypic classes to dicamba is poorly understood. Additionally, the effect of growth stage on sweet corn sensitivity to dicamba is inadequately described. The objective of this work was to quantify the significance of application timing, formulation, and CYP genotypic class on sweet corn response to dicamba. Hybrids representing each of the three CYP genotypes (Nsf1Nsf1, Nsf1nsf1, nsf1nsf1), were treated with dicamba or dicamba + CSA at one of three growth stages: V3, V6, or V9. Across all timing the nsf1nsf1 hybrid was the most damaged by dicamba application, displaying higher injury ratings and lower yield compared to the Nsf1Nsf1 or Nsf1nsf1 hybrids. The V9 growth stage was the most susceptible time for dicamba injury regardless of genotypic class. The addition of the CSA to dicamba applications reduced the injury from V9 dicamba applications however it did not completely eliminate the injury. The use of Nsf1Nsf1 or Nsf1nsf1 hybrids along with herbicide safeners may be useful in reducing injury from dicamba and other CYP-metabolized herbicides.