Persistence Behaviour of Fungicide Tebuconazole in a Viticulture Application

Dissipation pattern and risk assessment of tebuconazole in grapes was studied following two application rates (250 and 500 mL ha^?1) under tropical humid climatic condition of West Bengal during 2009–2010. Residues of tebuconazole were confirmed by liquid chromatography–mass spectrometry. The average recoveries were found 87.53 % and 89.67 % for grapes and cropped soil respectively. Following the first order kinetics the fungicide dissipates in grapes with a half-life (T_1/2) value ranges between 2.62 and 2.86 days irrespective of seasons and doses. No residues of tebuconazole were detected in harvest grapes and soil samples which refers that, tebuconazole does not possess any background contamination property in grapes. So it may be concluded from the study that tebuconazole does not possess any toxicological property when applied at the recommended dose.     

Persistence of Imidacloprid on Grape Leaves,Grape Berries and Soil

Residues of imidacloprid were estimated in grape leaves, grape berries and soil following four applications of Confidor 200SL at 400 and 800 mL ha⁻¹ using 1,000 L water. The average initial deposits of imidacloprid on grape leaves were found to be 10.01 and 16.97 mg kg⁻¹ at single and double dosages, respectively. These residues of imidacloprid dissipated to be the extract of 98.8% and 97.0%, respectively, at single and double dosages in 15 days, with half-life period of 2.35 and 2.97 days. Residues of imidacloprid in grape berries at harvest time were observed to below determination limit of 0.05 mg kg⁻¹ at single dose and 0.06 mg kg⁻¹ at double dose. However, acceptable daily intake (ADI) of imidacloprid is 0.06 mg kg⁻¹ body weight day⁻¹, which means an adult of 60 kg and a child of 10 kg can safely tolerate intake of 3,600 and 600 μg imidacloprid, respectively, without any appreciable risk to their life. Assuming consumption of 200 g grape berries contaminated at 0.06 mg kg⁻¹, it will lead to an intake of only 12 μg of imidacloprid, which is quite safe for a child as well as for an adult. Hence, the use of imidacloprid on grape crop seems to be toxicologically acceptable.     

Persistence of Acephate and Cypermethrin on Cotton Leaves,Cottonseed, Lint and Soil

Following foliar applications of combination formulation (cypermethrin 5% + acephate 45% DF) at 850 and 1,700 g ha(-1), resulting in active application of acephate at 382.5 and 765 g a.i. ha(-1) whereas active application of cypermethrin at 42.5 and 85 g a.i. ha(-1), the average initial deposits of acephate on cotton leaves were found to be 13.45 and 27.73 mg kg(-1), at single and double the doses of application, respectively. Residues of acephate declined below detectable level of 0.02 mg kg(-1) after 15 days of applications at application rates with t ((1/2)) values of 1.56 and 0.68 days, respectively. Similarly, the average initial deposits of cypermethrin were found to be 22.31 and 32.45 mg kg(-1), respectively. Cypermethrin residues reached below its detectable level of 0.02 mg kg(-1) after 21 days of its application at both the dosages of application. The half-life values for cypermethrin were observed to be 0.71 and 0.69 days, corresponding to single and double the dose of application, respectively. Interestingly, none of the samples of cottonseed, lint and soil showed presence of acephate or cypermethrin at the detection limit of 0.02 mg kg(-1) at first pick of the harvest time of the crop.     

Persistence of Trifloxystrobin and Tebuconazole on Grape Leaves, Grape Berries and Soil

Following four foliar applications of Nativo 75 WG (trifloxystrobin 25% + tebuconazole 50%) on grapes @ 175 and 350 g/ha, resulting in active applications of trifloxystrobin @ 43.75 and 87.5 g a.i./ha and that of tebuconazole @ 87.5 and 175 g a.i./ha, the average initial deposits of trifloxystrobin were observed to be 7.76 and 15.53 mg/kg, respectively, at single and double the application rates. These residue levels dissipated to >85% after 10 days of its application at both the dosages. Similarly, the average initial deposits of tebuconazole were observed to be 13.84 and 26.55 mg/kg at single and double the application rate, respectively. These residue levels dissipated to >90% after 10 days of application at both the dosages. The half-life (t _1/2) periods of trifloxystrobin on grape leaves were observed to be 2.92 and 3.48 days at single and double application rates, respectively, whereas these values were 2.68 and 3.96 days for tebuconazole. Ripe grape berries and soil samples collected at harvest which happened to be 34 days after the last application, did not show the presence of residues of trifloxystrobin and tebuconazole at their determination limit of 0.01 and 0.02 mg/kg, respectively.     

Persistence Behaviour of Thiacloprid Residues in/on Green Tea Leaves,Processed Tea and Tea Infusion

Thiacloprid residues were estimated in green tea leaves, processed tea and tea infusion by HPLC-Diode Array detection. The average initial deposits of thiacloprid (Alanto 240 SC) on the green tea leaves were found to be 3.72 and 6.77 μg g^?1 at single and double doses, respectively. The results showed that thiacloprid dissipated faster in green tea leaves following a first order reaction kinetics at both application rates. The amount of dissipation in 14 days was 93.37 % and 91.62 % for single and double doses respectively. Half life (T_1/2) for degradation of thiacloprid in green tea leaves were observed to be 3.34 and 3.58 days at single and double doses respectively. Thiacloprid residues in processed tea ranged from 0.16 to 0.63 μg g^?1 on seventh day and no residues could be detected on 14th day at single dose. Infusion study indicated that thiacloprid did not infuse into tea liquor from processed tea. The limit of determination was found to be 0.05 μg g^?1.     

Leaching Behaviour and Enhanced Phytoextraction of Additives for Cadmium-Contaminated Soil by Pennisetum sp.

Bulletin of Environmental Contamination and Toxicology - The leaching behavior of five additives, including citric acid (CA), wood vinegar (WV), 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP),...     

Evaluation of the Leaching Potential of Anthranilamide Insecticides Through the Soil

The soil nematode Caenorhabditis elegans was used in 24-h acute exposures to arsenic (As), copper (Cu) and glyphosate (GPS) and to mixtures of As/Cu and As/GPS to investigate the effects of mixture exposures in the worms. A synergistic type of interaction was observed for acute toxicity with the As/Cu and As/GPS mixtures. Sublethal 24-h exposures of 1/1000, 1/100 and 1/10 of the LC50 concentrations for As, Cu and GPS individually and for As/Cu and As/GPS mixtures were conducted to observe responses in locomotory behavior (head thrashing), reproduction, and heat shock protein expression. Head thrash frequency and reproduction exhibited concentration dependent decreases in both individual and combined exposures to the tested chemical stressors, and showed synergistic interactions even at micromolar concentrations. Furthermore, the HSP70 protein level was significantly increased following exposure to individual and combined chemical stressors in wild-type C. elegans. Our findings establish for the first time the effects of exposure to As/GPS and As/Cu mixtures in C. elegans.     

Quinalphos Persistence and Leaching Under Field Conditions and Effects of Residues on Dehydrogenase and Alkaline Phosphomonoesterases Activities in Soil

No abstract available.     

Persistence Behaviour of Thiamethoxam and Lambda Cyhalothrin in Transplanted Paddy

A field study was conducted in Pre-Kharif season 2007 on paddy to determine the persistence of thiamethoxam (12.6%) and lambda cyhalothrin (9.4%) [in a ‘Readymix’ formulation Alika 247 ZC], following the application of 33 g. a.i. ha⁻¹ (T₁) and 66 g. a.i. ha⁻¹ (T₂). Spraying of insecticide was done during milking stage of the crop (63 days after transplantation). Thiamethoxam and lambda cyhalothrin residues were estimated by HPLC and GLC respectively. The half-life values were 5.2–5.8 and 4.8 days for thiamethoxam and lambda cyhalothrin respectively. No residue was detected in the harvested paddy, straw, grain, and soil samples.     

Toxicity Persistence in Runoff Water and Soil in Experimental Soybean Plots Following Chlorpyrifos Application

Toxicity persistence in runoff water and soil was studied in experimental soybean plots in successive runoff events produced by an irrigation system. Three chlorpyrifos applications throughout the growing period were assayed. Runoff and soil toxicity to the amphipod Hyalella curvispina and the fish Cnesterodon decemmaculatus was assessed. Toxicity persistence to H. curvispina was shorter in the early and midseason applications (23–28 and 21–69 days in runoff and soil, respectively) and longer in the late application (more than 140 days). The same trend was observed for C. decemmaculatus: 13 days for early and 56 for the late application.     

Persistence and Metabolism of Fipronil in Sugarcane Leaves and Juice

Fipronil gives effective control of early shoot borer and termites in sugarcane. The persistence and metabolism of fipronil in sugarcane leaves and juice were studied following application of fipronil (Regent 0.3 G) at 75 and 300 g a.i. ha^?1. Samples of sugarcane leaves were collected at various time intervals. Samples of sugarcane juice were collected at harvest. Residues of fipronil and its metabolites were quantified by gas liquid chromatograph. The limit of quantification of fipronil and its metabolites was 0.01 mg kg^?1 for sugarcane leaves and juice. Total residues of fipronil and its metabolites in sugarcane leaves after 7 days of its application at 75 and 300 g a.i. ha^?1 were 0.26 and 0.66 mg kg^?1, respectively. Residues could not be detected after 60 and 90 following fipronil application at either concentration. In sugarcane leaves, fipronil was found to be the main constituent, followed by its metabolites amide, desulfinyl, sulfone and sulfide. Samples of sugarcane juice did not reveal the presence of fipronil or its metabolites following its application at both the dosages at harvest.     

Synergy of the Tropical Earthworm Pontoscolex corethrurus and Oil Palm Bagasse in the Removal of Heavy Crude Oil

The tropical endogeic earthworm Pontoscolex corethrurus, a non-standard species used in ecotoxicity, has been found in crude oil-contaminated habitats. We estimated the removal of total hydrocarbons from heavy crude “Maya” oil on an artificially contaminated soil with a median lethal concentration of P. corethrurus and an addition of oil palm bagasse. P. corethrurus had a high survival rate, and the addition of oil palm bagasse led to a greater growth and an increase in abundance of bacteria and fungi. The activity of P. corethrurus and the nutritional quality of oil palm bagasse had a significant impact on the removal of a larger amount of petroleum hydrocarbons from contaminated soil. We concluded that the endogeic earthworm P. corethrurus and oil palm bagasse acted synergistically to achieve a more effective removal of total petroleum hydrocarbons from soil. These results show the potential for using P. corethrurus to remove, either directly or indirectly, crude oil from soil.

     

Effect of Soil Type, Soil pH, and Microbial Activity on Persistence of Clodinafop Herbicide

No abstract available.