Investigating the Efficacy of Selected Very-Long-Chain Fatty Acid-Inhibiting Herbicides on Iowa Waterhemp (<i>Amaranthus tuberculatus</i>) Populations with Evolved Multiple Herbicide Resistances
Very long chain fatty acid (VLCFA)-inhibiting herbicides (Herbicide group (HG) 15) have been applied to corn and soybean fields in Iowa since the 1960s. The VLCFA-inhibiting herbicides are now applied more frequently to control multiple herbicide-resistant (MHR) waterhemp (<i>Amaranthus tuberc...
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-03-01
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| Series: | Agronomy |
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| Online Access: | https://www.mdpi.com/2073-4395/11/3/595 |
| _version_ | 1827697157801508864 |
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| author | Eric A. L. Jones Micheal D. K. Owen |
| author_facet | Eric A. L. Jones Micheal D. K. Owen |
| author_sort | Eric A. L. Jones |
| collection | DOAJ |
| description | Very long chain fatty acid (VLCFA)-inhibiting herbicides (Herbicide group (HG) 15) have been applied to corn and soybean fields in Iowa since the 1960s. The VLCFA-inhibiting herbicides are now applied more frequently to control multiple herbicide-resistant (MHR) waterhemp (<i>Amaranthus tuberculatus</i> Moq. J.D. Sauer) populations that are ubiquitous across the Midwest United States as resistance to the VLCFA-inhibiting herbicides is not widespread. Waterhemp has evolved multiple resistances to herbicides from seven sites of action (HG 2, 4, 5, 9, 14, 15, and 27), and six-way herbicide-resistant populations have been confirmed. Thus, the objective of this study was to determine if selected Iowa waterhemp populations are less sensitive to VLCFA-inhibiting herbicides when additional herbicide resistance traits have evolved within the selected population. Dose–response assays were conducted in a germination chamber to determine the efficacy of three selected VLCFA-inhibiting herbicides (acetochlor, <i>S</i>-metolachlor, and flufenacet) on selected Iowa MHR waterhemp populations. An herbicide-susceptible, three-way, four-way, and five-way herbicide-resistant waterhemp population responded to the herbicide treatments differently; however, several of the four-way and five-way herbicide-resistant populations exhibited resistance ratios greater than 1 when treated with acetochlor and <i>S</i>-metolachlor. Selected four-way herbicide-resistant waterhemp populations from Iowa were subjected to a dose–response assay in the field using the same VLCFA-inhibiting herbicides, and all herbicides achieved control greater than 80% at the maximum labeled rate. The results of the experiments provide evidence that some MHR waterhemp populations may exhibit decreased susceptibility the VLCFA-inhibiting herbicides, but generally, these herbicides remain efficacious on Iowa MHR waterhemp populations. |
| first_indexed | 2024-03-10T13:03:14Z |
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| institution | Directory Open Access Journal |
| issn | 2073-4395 |
| language | English |
| last_indexed | 2024-03-10T13:03:14Z |
| publishDate | 2021-03-01 |
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| series | Agronomy |
| spelling | doaj.art-c7424de5021047cb83e82be8efa285722023-11-21T11:22:07ZengMDPI AGAgronomy2073-43952021-03-0111359510.3390/agronomy11030595Investigating the Efficacy of Selected Very-Long-Chain Fatty Acid-Inhibiting Herbicides on Iowa Waterhemp (<i>Amaranthus tuberculatus</i>) Populations with Evolved Multiple Herbicide ResistancesEric A. L. Jones0Micheal D. K. Owen1Department of Crop and Soil Science, North Carolina State University, Raleigh, NC 27607, USADepartment of Agronomy, Iowa State University, Ames, IA 50011, USAVery long chain fatty acid (VLCFA)-inhibiting herbicides (Herbicide group (HG) 15) have been applied to corn and soybean fields in Iowa since the 1960s. The VLCFA-inhibiting herbicides are now applied more frequently to control multiple herbicide-resistant (MHR) waterhemp (<i>Amaranthus tuberculatus</i> Moq. J.D. Sauer) populations that are ubiquitous across the Midwest United States as resistance to the VLCFA-inhibiting herbicides is not widespread. Waterhemp has evolved multiple resistances to herbicides from seven sites of action (HG 2, 4, 5, 9, 14, 15, and 27), and six-way herbicide-resistant populations have been confirmed. Thus, the objective of this study was to determine if selected Iowa waterhemp populations are less sensitive to VLCFA-inhibiting herbicides when additional herbicide resistance traits have evolved within the selected population. Dose–response assays were conducted in a germination chamber to determine the efficacy of three selected VLCFA-inhibiting herbicides (acetochlor, <i>S</i>-metolachlor, and flufenacet) on selected Iowa MHR waterhemp populations. An herbicide-susceptible, three-way, four-way, and five-way herbicide-resistant waterhemp population responded to the herbicide treatments differently; however, several of the four-way and five-way herbicide-resistant populations exhibited resistance ratios greater than 1 when treated with acetochlor and <i>S</i>-metolachlor. Selected four-way herbicide-resistant waterhemp populations from Iowa were subjected to a dose–response assay in the field using the same VLCFA-inhibiting herbicides, and all herbicides achieved control greater than 80% at the maximum labeled rate. The results of the experiments provide evidence that some MHR waterhemp populations may exhibit decreased susceptibility the VLCFA-inhibiting herbicides, but generally, these herbicides remain efficacious on Iowa MHR waterhemp populations.https://www.mdpi.com/2073-4395/11/3/595cross-resistanceherbicide resistanceresidual herbicidesweed management |
| spellingShingle | Eric A. L. Jones Micheal D. K. Owen Investigating the Efficacy of Selected Very-Long-Chain Fatty Acid-Inhibiting Herbicides on Iowa Waterhemp (<i>Amaranthus tuberculatus</i>) Populations with Evolved Multiple Herbicide Resistances Agronomy cross-resistance herbicide resistance residual herbicides weed management |
| title | Investigating the Efficacy of Selected Very-Long-Chain Fatty Acid-Inhibiting Herbicides on Iowa Waterhemp (<i>Amaranthus tuberculatus</i>) Populations with Evolved Multiple Herbicide Resistances |
| title_full | Investigating the Efficacy of Selected Very-Long-Chain Fatty Acid-Inhibiting Herbicides on Iowa Waterhemp (<i>Amaranthus tuberculatus</i>) Populations with Evolved Multiple Herbicide Resistances |
| title_fullStr | Investigating the Efficacy of Selected Very-Long-Chain Fatty Acid-Inhibiting Herbicides on Iowa Waterhemp (<i>Amaranthus tuberculatus</i>) Populations with Evolved Multiple Herbicide Resistances |
| title_full_unstemmed | Investigating the Efficacy of Selected Very-Long-Chain Fatty Acid-Inhibiting Herbicides on Iowa Waterhemp (<i>Amaranthus tuberculatus</i>) Populations with Evolved Multiple Herbicide Resistances |
| title_short | Investigating the Efficacy of Selected Very-Long-Chain Fatty Acid-Inhibiting Herbicides on Iowa Waterhemp (<i>Amaranthus tuberculatus</i>) Populations with Evolved Multiple Herbicide Resistances |
| title_sort | investigating the efficacy of selected very long chain fatty acid inhibiting herbicides on iowa waterhemp i amaranthus tuberculatus i populations with evolved multiple herbicide resistances |
| topic | cross-resistance herbicide resistance residual herbicides weed management |
| url | https://www.mdpi.com/2073-4395/11/3/595 |
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