Analysis of tebuconazole residues in coconut water, kernel and leaves using LC-MS/MS

Comprehensive multiresidue chromatographic methods for monitoring pesticides in agricultural areas and corresponding plant protection zones

This article reports a comprehensive analytical method for the identification and quantification of a broad range of pesticides in green plant crops. The sample preparation method for pesticides involved an optimization of the QuEChERS-based extraction protocol, with sample mass, volume of added water, and the type of cleanup sorbent as variables. A sorbent combination based on ENVI-Carb and ChloroFiltr was examined. A highly efficient method was developed for the purification of plant extracts with 900 mg MgSO4, 150 mg PSA, and 15 mg ENVI-Carb at the d-SPE stage, combined with gas chromatography and liquid tandem mass spectrometry for the determination of 197 pesticides in crop plants containing chlorophyll. The method was validated in accordance with the requirements of international guidelines SANTE/11312/2021. The method was applied to quantify pesticide residues in 29 pairs of green crop plants and plants from the corresponding crop protection zone to verify whether the zones are effective barriers to prevent pesticides from penetrating outside agricultural areas. The number and types of agrochemical preparations were chosen by farmers. In total, more than 60 one- and several-component pesticide formulations were applied to the crops included in the study. The pesticide residues were detected in 21 crop samples and 3 samples from protection zones. Epoxiconazole, an active substance that was banned for use in 2021, was found in a spring barley sample. Based on the conducted research, the effectiveness of the protection zones has been clearly demonstrated, and it has been proven that environmental migration of pesticides and unauthorized agricultural practices pose a risk to ecosystems.

Persistence of foliar applied and pre-storage seed-treated insecticides in rice and its processed products

A field study was conducted to investigate the persistence of foliar-applied thiamethoxam 25% WG at a rate of 25 g ai ha-1 and chlorantraniliprole 18.5% SC at 30 g ai ha-1 in various parts of rice plants, including whole grain rice, brown rice, bran, husk, straw, and cooked rice. Liquid Chromatography-Mass spectrometry/Mass spectrometry was used for sample analysis. Chlorantraniliprole residues were found to persist in whole grains, bran, husk, and straw at the time of harvest, while thiamethoxam residue was not detected in harvested grains, processed products, or straw. The study concluded that foliar-applied chlorantraniliprole and thiamethoxam did not pose any dietary risk in cooked rice. In a pre-storage seed treatment study, thiamethoxam 30% FS at 3 mL kg-1 was evaluated against Angoumois grain moth infestation during storage. The seeds remained unharmed for nine months and exhibited significantly less moth damage (2.0%) even after twelve months of storage. Thiamethoxam residues persisted for more than one year in whole rice grain, brown rice, bran, and husk with seed treatment, with higher residue levels observed in bran and husk. Parboiling and cooking led to the degradation of thiamethoxam residues.

Study of insecticide translocation in coconut palm trees after using pressurized endotherapy

Alternative techniques for applying agricultural products, such as pressurized endotherapy, have shown promise in pest and disease control in coconut palms (Cocos nucifera Linn.). In this work, azadirachtin and abamectin were applied by pressurized endotherapy to control Brassolis sophorae. Twelve different treatments were carried out, and in all of them, at least one plant had the larvae completely dead four and five days after endotherapeutic applications, and all the others died within the next few hours. Leaf and fruit analyses were performed to determine the concentration over time. High concentrations of abamectin were observed after 15 and 30 days on leaves when applied in larger volumes. In fruits, no residue was found regardless of the applied concentration. Analytical methods were developed and validated for leaves and fruits to analyze insecticide residues using LC-MS/MS and modified QuEChERS acetate according to SANTE/11813/2017 guidelines. The insecticide translocation tests in the leaves and the high mortality of insects showed that pressurized endotherapy is a technique to be considered for future studies in controlling B. sophorae in coconut palm trees.

Effects of Pymetrozine and Tebuconazole with Foliar Fertilizer Through Mixed Application on Plant Growth and Pesticide Residues in Cucumber

The mixed application of pesticides and foliar fertilizer has been widely used in the production of cucumber, however, their effects on plant growth and pesticide dissipation are still unclear. In this study, the effects of mixed application of pymetrozine, tebuconazole and foliar fertilizer on the cucumber plant growth and pesticide dissipation were investigated simultaneously. The results show that the mixed use of pymetrozine, tebuconazole, especially adding foliar fertilizer, improved the physiological indexes (i.e., area, nitrogen content and chlorophyll content of the leaves, and root growth) of cucumber plants compared to those with the application of single pesticide. Meanwhile, it can significantly affect the dissipation of pymetrozine even in the slower growth matrices (lower leaves, stems, and plants). The residue of tebuconazole in cucumber plants was affected by the combination of formulation type and foliar fertilizer. This study can provide data for scientifically guiding the mixed application of pesticide and fertilizer.