Weed Science Commons^™

Overexpression Of Acetyl Coa Carboxylase 1 And 3 (Accase1 And Accase3), And Cyp81a21 Were Related To Cyhalofop Resistance In A Barnyardgrass Accession From Arkansas, Fidel Gonzalez-Torralva, Jason K. Norsworthy

Crop, Soil and Environmental Sciences Faculty Publications and Presentations

Barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.] is the most difficult-to-control weed species of rice production systems worldwide. It has evolved resistance to different herbicide sites of action, including the acetyl-CoA carboxylase (ACCase)-inhibiting herbicides. Target-site mutations conferring resistance to ACCase-inhibiting herbicides are well documented; however, the role of the different ACCase genes in conferring resistance to cyhalofop-p-butyl (cyhalofop), an ACCase-inhibiting herbicide, remains poorly understood. This research assessed the contribution of gene amplification and expression of ACCase genes in a cyhalofop-resistant barnyardgrass accession. Additionally, the expression of glutathione-S-transferases (GSTs) and cytochrome P450 monooxygenases (P450s) genes as possible …

Assessment Of Dicamba And 2,4-D Residues In Palmer Amaranth And Soybean, Maria Leticia Zaccaro-Gruener, Jason K. Norsworthy, Leonard B. Piveta, L. Tom Barber, Andronikos Mauromostakos

Crop, Soil and Environmental Sciences Faculty Publications and Presentations

Off-target movement of 2,4-D and dicamba is sometimes to blame as the cause of symptoms observed in weeds growing in production fields. Pesticide regulatory authorities routinely sample tissues of weeds or crops from fields under investigation for potential illegal use of auxin herbicides. This research aimed to determine if analytical tests of herbicide residue on soybean or Palmer amaranth vegetation treated with dicamba or 2,4-D could be used to differentiate between rates applied and how the residue levels decay over a 1-mo interval. Four rates of each herbicide (1X, 0.1X, 0.01X, and 0.001X) were applied, with a 1X rate of …

Herbicide Physiology And Environmental Fate, Luis Avila, Nilda Roma-Burgos

Crop, Soil and Environmental Sciences Faculty Publications and Presentations

Editorial

Herbicide Physiology and Environmental Fate

Effect Of Rice Leaf Stage On Tolerance To Benzobicyclon In A Drill-Seeded Production System, Jake A. Patterson, Jason K. Norsworthy, Thomas R. Butts, Edward E. Gbur

Crop, Soil and Environmental Sciences Faculty Publications and Presentations

Benzobicyclon is a new postflood-applied herbicide that was registered for use in U.S. rice (Oryza sativa L.) in 2021 by Gowan Company. Therefore, research was conducted to evaluate tolerance of commonly grown rice cultivars to benzobicyclon. In 2018 and 2019, field experiments were conducted near Stuttgart, AR to evaluate the influence of growth stage on rice tolerance to benzobicyclon, and to evaluate pure line and hybrid rice tolerance to benzobicyclon following repeated use of acetolactate synthase-inhibiting herbicides. In one of two years, rice growth stage (leaf number) at application impacted tolerance to benzobicyclon. In 2018, the two-leaf application of …

Fenclorim Rice Safening And Weed Control With Fall-Applied Acetochlor And Pyroxasulfone, Tristen H. Avent, Jason K. Norsworthy, Thomas R. Butts, Trenton Roberts, Nicholas R. Bateman

Crop, Soil and Environmental Sciences Faculty Publications and Presentations

Applications of very long-chained fatty acid elongase (VLCFA)-inhibiting herbicides are currently not labeled within U.S. rice (Oryza sativa L.) production but have been used in Asian rice production to suppress weedy rice and control other annual grasses and small-seeded broadleaves. Therefore, separate experiments were initiated in the fall of 2019 and 2020 to evaluate rice tolerance and weedy rice (O. sativa L.) control with acetochlor and pyroxasulfone in the following spring. A three-factor experiment within a randomized complete block design was implemented with the factors being (1) herbicide choice (acetochlor or pyroxasulfone), (2) a low or high herbicide …

Assessment Of Efficacy And Mechanism Of Resistance To Soil-Applied Ppo Inhibitors In Amaranthus Palmeri, Gulab Rangani, Aimone Perri, Reiofeli A. Salas-Perez, Jens Lerchl, Srikanth Kumar Karaikal, Juan Camilo Velásquez, Nilda Roma-Burgos

Crop, Soil and Environmental Sciences Faculty Publications and Presentations

Resistance to protoporphyrinogen oxidase (PPO) inhibitors in Palmer amaranth is a major concern, given the high selection pressure and increasing number of populations with reduced sensitivity to PPO herbicides in the US. We evaluated the effect of five soil-applied herbicides on Palmer amaranth (Amaranthus palmeri S. Wats.) populations collected in 2014 and 2015 in Arkansas, USA. Soil-applied saflufenacil, sulfentrazone, and flumioxazin reduced the seedling emergence 91–100%; however, fomesafen and oxyfluorfen showed reduced (63–90%) efficacy on some populations. Target-site mutation (TSM) is the major mechanism of resistance to PPO herbicides; therefore, six populations showing resistance to soil-applied fomesafen were selected for …

Evaluation Of Rice Tolerance And Weed Control With Acetochlor And Fenclorim, Tristen H. Avent, Jason K. Norsworthy, Thomas R. Butts, Trenton L. Roberts, Nicholas R. Bateman

Crop, Soil and Environmental Sciences Faculty Publications and Presentations

Many problematic weeds have evolved resistance to herbicides in mid-southern U.S. rice fields. With the lack of new effective herbicides, rice producers seek alternatives that are currently not labeled for rice production. Inhibitors of very-long chain fatty acid elongase (VLCFA) are currently not labeled for use with U.S. rice crops but are labeled for use in other U.S. row cropping systems and rice production in Asia. Previous research has demonstrated the utility of VLCFA inhibitors for weed control in rice; however, these herbicides induce variable amounts of injury to the crop when applied early in the growing season. Experiments were …

Rice Tolerance To Acetochlor With A Fenclorim Seed Treatment, Tristen H. Avent, Jason K. Norsworthy, Thomas R. Butts, Trenton Roberts, Nicholas R. Bateman

Crop, Soil and Environmental Sciences Faculty Publications and Presentations

Rice producers in the United States need effective herbicides to control problematic weeds. Previous research has demonstrated that acetochlor can provide in-season weed control in rice; however, undesirable injury is common. Thus, trials were initiated in 2020 and 2021 to evaluate 1) rice cultivar tolerance to microencapsulated (ME) acetochlor with the use of a fenclorim seed treatment at 2.5 g ai kg⁻¹ of seed; 2) a dose-response of a fenclorim seed treatment with ME acetochlor; and 3) rice tolerance to fenclorim and ME acetochlor under cool, wet conditions. For all trials, acetochlor was applied delayed-preemergence (4 to 7 d …