Resistance to very-long-chain fatty-acid (VLCFA)-inhibiting herbicides in multiple field-selected rigid ryegrass (Lolium rigidum) populations

Weed Science ◽  
2019 ◽  
Vol 67 (3) ◽  
pp. 267-272 ◽  
Author(s):  
David J. Brunton ◽  
Peter Boutsalis ◽  
Gurjeet Gill ◽  
Christopher Preston

AbstractFive populations of rigid ryegrass (Lolium rigidumGaudin) from fields across cropping regions in southern Australia were suspected of having resistance to thiocarbamates, chloroacetamides, and sulfonylisoxazoline herbicides. Resistant (R) populations 375-14, 198-15, 16.2, EP162, RAC1, and A18 and two susceptible (S) populations (SLR4 and VLR1) were included in a dose–response study. All suspected R populations expressed resistance to one or all herbicides (thiocarbamates, chloroacetamides, and pyroxasulfone). Population 198-15 exhibited the highest LD50to triallate (44.7-fold), prosulfocarb (45.7-fold),S-metolachlor (31.5-fold), and metazachlor (27.2-fold) compared with the S populations. Populations 198-15 and 375-14 were also resistant to pyroxasulfone (13.5- and 14.9-fold) compared with the S populations, as was population EP162. This study documents the first case of field-evolved resistance to thiocarbamate, chloroacetamide, and sulfonylisoxazoline herbicides inL. rigidum.

Agronomy ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 595
Author(s):  
Eric A. L. Jones ◽  
Micheal D. K. Owen

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 (Amaranthus tuberculatus 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, S-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 S-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.


2000 ◽  
Vol 41 (1) ◽  
pp. 41-47 ◽  
Author(s):  
Karin A. J.M. van der Lee ◽  
Michaël M. Vork ◽  
Johan E. De Vries ◽  
Peter H.M. Willemsen ◽  
Jan F.C. Glatz ◽  
...  

2014 ◽  
Vol 146 (5) ◽  
pp. S-110-S-111
Author(s):  
Arivarasu Natarajan Anbazhagan ◽  
Shubha Priyamvada ◽  
Tarunmeet Gujral ◽  
Waddah A. Alrefai ◽  
Pradeep K. Dudeja ◽  
...  

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