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Analysis of pesticide residues in irrigated rice grains is important for food security. In this study, we analyzed accelerated solvent extraction (ASE) conditions for the extraction of thiamethoxam and chlorantraniliprole insecticides from rice hulls, rice bran, and polished rice grains. Several variables, including extraction solvent, extraction temperature, extraction pressure, cell size, static extraction time, and sample concentration, were investigated. The average recoveries of the three matrixes were between 89.7 and 109.7% at the fortification level of 0.75 mg/kg. The optimum ASE operating conditions were acetonitrile (100%) as extraction solvent, extraction temperature of 75°C for rice hulls and 100°C for rice bran and polished rice grains, extraction cell pressure of 10.3 MPa, 22 mL cell size, and two extraction cycles. The total extraction time was approximately 25 min. The extracted volume was evaporated to dryness and the residues were redissolved in 2 mL acetonitrile after 1 min of vortexshaking. Thiamethoxam and chlorantraniliprole were analyzed by ultra-HPLC with tandem MS. In conclusion, ASE in rice hulls, rice bran, and polished rice grains offers the possibility of a fast and simple method for obtaining a quantitative extraction of the studied pesticides. [ABSTRACT FROM AUTHOR]

Abstract: Saflufenacil is a new herbicide for broadleaf weed control in various crops. In rice, saflufenacil can be a prospective combination partner to complement the broadleaf weed control of herbicides such as imazethapyr. This study was established to evaluate 1) rice tolerance and 2) weed control of red rice (Oryza sativa L.) and hemp sesbania (Sesbania exaltata P. Mill.) to saflufenacil tank-mixed with imazethapyr. The experiment was conducted during 2009 and 2010 at the Texas A&M AgriLife Research and Extension Center located at Beaumont, TX. Treatments included a check, an imazethapyr treatment alone (70 g a.i. ha−1 at the 1- to 2-leaf stage (EPOST) plus 70 g a.i. ha−1 at the 4- to 6-leaf stage (LPOST)), and four saflufenacil doses (12.5, 18.75, 25, and 50 g a.i. ha−1) applied at EPOST and LPOST. Imazethapyr treatment was applied to all saflufenacil treatments. Rice injury increased with doses of saflufenacil and injury up to 83% was observed at 7 DAA when 50 g ha−1 was applied EPOST. Subsequent evaluations indicated less injury over time demonstrating rice recovery from saflufenacil treatments. No injury was observed in the imazethapyr treatment alone. Rice plants seemed to recover faster from LPOST application injury than EPOST. Hemp sesbania control was ≥88% in all saflufenacil treatments in evaluations conducted before harvest indicating effective control throughout the growing season. Red rice control was 100% for all treated plots containing imazethapyr in both years. Therefore, imazethapyr control of red rice was not adversely affected by tank-mixing with saflufenacil. Although injury was significantly higher in the highest doses of saflufenacil, rice yield was not adversely altered by the herbicide treatments. In summary, rice was injured at the highest doses of saflufenacil, but injury did not reduce rice yield. Hemp sesbania was effectively controlled by saflufenacil (>90% on average). No antagonistic interactions between saflufenacil and imazethapyr were observed with red rice control. Saflufenacil appears to be an effective herbicide candidate for broadleaf control in rice. [Copyright &y& Elsevier]

Herbicide promotes physiological and biochemical changes even in tolerant species. The objective of this study was to evaluate the interference of the herbicides clodinafop-propargyl and 2,4-D in the antioxidant system of wheat, and iodosulfuron-methyl in wheat and ryegrass. Two studies, divided into three experiments, were conducted in an entirely randomized design in a greenhouse and phytotron. The first study tested herbicides iodosulfuron-methyl, clodinafop-propargyl, 2,4-D, and a control without application in wheat. The second, divided into two experiments with wheat and ryegrass, tested iodosulfuron-methyl doses (0, 1.75, 3.5, and 7.0 g a.i. ha-1). The variables analyzed were the concentrations of chlorophylls a, b, carotenoids, hydrogen peroxide (H2O2), lipid peroxidation (TBARS), electrolyte leakage, and antioxidant system activity. The herbicide treatments iodosulfuron-methyl, clodinafop-propargyl, and 2,4-D decreased the concentrations of chlorophylls and carotenoids in wheat plants. The herbicides promoted oxidative stress with increased H2O2 and TBARS concentrations. Increasing the dose of iodosulfuron-methyl provided a reduction in the activity of the enzymatic antioxidant system in wheat and ryegrass. [ABSTRACT FROM AUTHOR]

Analysis of pesticide residues in irrigated rice grains is important for food security. In this study, we analyzed accelerated solvent extraction (ASE) conditions for the extraction of thiamethoxam and chlorantraniliprole insecticides from rice hulls, rice bran, and polished rice grains. Several variables, including extraction solvent, extraction temperature, extraction pressure, cell size, static extraction time, and sample concentration, were investigated. The average recoveries of the three matrixes were between 89.7 and 109.7% at the fortification level of 0.75 mg/kg. The optimum ASE operating conditions were acetonitrile (100%) as extraction solvent, extraction temperature of 75°C for rice hulls and 100°C for rice bran and polished rice grains, extraction cell pressure of 10.3 MPa, 22 mL cell size, and two extraction cycles. The total extraction time was approximately 25 min. The extracted volume was evaporated to dryness and the residues were redissolved in 2 mL acetonitrile after 1 min of vortex-shaking. Thiamethoxam and chlorantraniliprole were analyzed by ultra-HPLC with tandem MS. In conclusion, ASE in rice hulls, rice bran, and polished rice grains offers the possibility of a fast and simple method for obtaining a quantitative extraction of the studied pesticides.

Adsorption and desorption of atrazine and its metabolites in vegetated filter strip soil (VFS) has not been evaluated, yet these data are needed to predict the transport of these compounds through the VFS. Adsorption and desorption parameters for atrazine, desethylatrazine (DEA), deisopropylatrazine (DIA), and hydroxyatrazine (HA) were compared between a cultivated Houston Black clay (CS) and an adjacent 12-year-old VFS established in a mixed stand of bermudagrass [Cynodon dactylon (L.) Pers.] and buffalograss [Buchloe dactyloides (Nutt. Engelm)]. Adsorption and desorption isotherms were determined by batch equilibrium. The evaluated chemical and physical properties of the VFS and CS were similar with the exception of a 1.7-fold increase in the organic carbon content of the VFS. Adsorption and desorption coefficients for atrazine were at least 59% higher in VFS than in CS. The adsorption coefficient for HA was 48% higher in VFS compared with CS, but desorption was not statistically different between soils. Adsorption and desorption coefficients for DEA and DIA were not statistically different between soils. The predicted order of mobility in CS is HA < atrazine = DIA = DEA. In VFS, the predicted order of mobility is HA < atrazine = DIA < DEA. These data indicate that the higher organic carbon in VFS will likely retard the transport of atrazine and HA to surface and ground waters; however, the transport rates of DEA and DIA will be similar between soils.