Search Results (59)

Selection forestry sustains timber production and stand structural complexity via partial harvesting. However, regeneration initiated by harvesting may function as fuel ladders, providing pathways for fire to reach the forest canopy. We sought potential mitigation approaches by simulating stand growth and potential wildfire behavior over a century in stands dominated by coast redwood (Sequoia sempervirens (Lamb. ex. D. Don) Endl.) on California’s north coast. We used the fire and fuels extension to the forest vegetation simulator (FFE-FVS) to compare group selection (GS) to single-tree selection silviculture with either low-density (LD) or high-density (HD) retention on a 20-year harvest return interval. These three approaches were paired with six options involving vegetation management (i.e., hardwood control or pre-commercial thinning (PCT)) with and without fuels treatments (i.e., prescribed fire or pile burning), or no subsequent vegetation or fuel treatment applied after GS, HD, or LD silviculture. Fuel treatment involving prescribed fire reduced hazardous fuel loading but lowered stand density and hence productivity. Hardwood control followed by prescribed fire mitigated potential wildfire behavior and promoted dominance of merchantable conifers. PCT of small young trees regenerating after selection harvests, followed by piling and burning of these cut trees, sustained timber production while reducing potential wildfire behavior by approximately 40% relative to selection silviculture without vegetation/fuel management, which exhibited the worst potential wildfire behavior. Full article

Phoxim is a pesticide extensively applied in mulberry fields, and residues may persist on leaves even after the recommended pre-harvest interval. However, the potential risks of these residues to Bombyx mori L. (Lepidoptera: Bombycidae) have long been overlooked. The results demonstrated that chronic low-dose exposure from the second to fifth instars significantly impaired silkworm development and silk production. Specifically, larvae in the 0.316 μg/mL treatment group (1/2 LC₅₀) exhibited a significant reduction in body weight, while the cocoon shell ratio was significantly decreased in both the 0.079 μg/mL (1/8 LC₅₀) and 1/2 LC₅₀ groups. Cocoon deformities were observed in the 0.032 μg/mL (1/20 LC₅₀), 1/8 LC₅₀, and 1/2 LC₅₀ groups. Histopathological analysis revealed silk gland damage in the treatment groups, with severity increasing with higher phoxim concentrations. Biochemical analyses indicated elevated malondialdehyde (MDA) levels accompanied by increased superoxide dismutase (SOD) and peroxidase (POD) activities. Notably, phoxim exposure selectively reduced juvenile hormone (JH) titers without affecting ecdysone titers. JH-regulated genes including the receptors Met1 and Met2, and transcription factors Kr-h1 and Dimm were downregulated, accompanied by suppressed expression of the fibroin synthesis gene Fib-H. These results collectively indicate that chronic low-concentration phoxim exposure disrupts endocrine regulation, damages silk gland integrity, and ultimately reduces silk production in silkworm. Full article

Grape cultivation is crucial due to its significant dietary benefits and the production of various byproducts. Fungicides, like boscalid, are frequently applied to protect grape crops from several disease, ensuring both yield and quality. However, the excessive or inappropriate application of boscalid may pose health risks to humans. Therefore, the objectives of this field study were (a) to assess the pre-harvest interval (PHI) and dissipation of boscalid in two table-grape varieties (Soultanina and Crimson) under field conditions and (b) evaluate the potential health risks associated with grape consumption for both adults and children. The residue of boscalid in the grapes was determined using a modified QuEChERS method coupled with a high-performance liquid chromatography diode array detector (HPLC–DAD). The dissipation of boscalid followed first- and second-order kinetics, with half-lives ranging from 3.32 to 6.42 days and PHIs from 8.11 to 10.90 days. The dietary risk assessment indicated that the early to mid-post application period could pose risks for both age groups, with children facing three times the risk of adults. Full article

Reducing food losses in apple production is becoming increasingly important, as the effects of climate change constitute a challenge to food production. Improving methods for determining fruit maturity at harvest leading to the longest storability is crucial, thereby facing more unpredictable seasonal weather conditions. In addition, the increasing temperature is affecting common maturity indices differently; thus, present practice may not be valid. In this study, a non-destructive, time-efficient method was used, tentatively indicating maturity. This study was performed during three climate-diverse years, reflecting more irregular climate conditions. Mid- to late-season cultivars ‘Frida’, ‘Ingrid Marie’, ‘Rubinstar’, and ‘Elise’ were harvested at different pre-determined I_AD (index of absorbance difference) intervals and stored for five months. Correlations between I_AD values at harvest and total losses after storage were found for all cultivars and years, while only a few correlations related to firmness after storage were found. Although a strong effect of year was related to correlations between I_AD and different quality parameters, no noticeably general differences could be found between the exceptionally warm year in comparison to the other investigated years. I_AD, as a maturity index, thus, seems to be resilient to changing temperatures and can be used as a complementary maturity index. Full article

The dissipation pattern and mobility of applied pesticides in the soil represent a crucial process for pesticide safety and subsequent groundwater contamination. In this study, two distinct experiments were conducted to explore the environmental fate, dissipation, and mobility of two pesticides, phorate and boscalid, in greenhouse conditions and laboratory soil column studies, respectively. The role of organic matter and growing conditions was evaluated during dissipation and mobility studies. In the first study, commercial formulations of phorate (10 G) and boscalid (20% SC) were sprayed in the designated greenhouse for Korean cabbage following the recommended dosage. A sequential collection of plant samples (e.g., 0, 7, 14, 21 days) was performed. On the other hand, three sets of packing columns were prepared (control, biochar-amended, and H₂O₂ treated). The effect of organic matter addition or removal during the leaching of pesticides was explored. A 14-day interval after the last spray was suggested for safe spraying. After 30 days of leachate collection, no pesticide residue was detected in the leaching water, indicating the immobility of the studied pesticides. However, the metabolic transformation of phorate was evident during this column study, with slight mobility within soil columns. In particular, phorate sulfoxide and sulfone were mostly detected in the top soil layer (vadose zone) of the soil column. In summary, phorate and boscalid were considered immobile pesticides with moderate persistence in the soils. The safe pre-harvest interval should be maintained to reduce the health risk of pesticides. Full article

Pepper is one of the most widely consumed foods around the world. China is the leading producer, while Mexico is the primary exporter. To support these roles, the responsible use of agrochemicals is essential. Additionally, investigating the factors influencing pesticide dissipation is critical to ensure that residue levels do not exceed established Maximum Residue Limits (MRLs) and to achieve the required pre-harvest interval (PHI). This is essential to prevent trade-related issues and mitigate potential health risks to consumers. Consequently, this study aims to evaluate the dissipation dynamics of acetamiprid, azoxystrobin, and β-cyfluthrin residues in jalapeño peppers cultivated under both greenhouse and open-field conditions. Three applications of a manufacturer’s suggested dosage were evaluated, with 7-day intervals between each. The residual content was quantified after 1 h and 1, 3, 7, 14, and 21 days following each application. A QuEChERS method utilizing ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS) and gas chromatography equipped with a micro electron capture detector (GC-µECD) to determine the pesticide residues was optimized and validated, obtaining suitable performance, with satisfactory linearity, detection and quantification limits, recovery rates, and accuracy. The dissipation curves were constructed from the residues and dissipation percentages of the pesticides over time, elucidating the initial residuality, accumulation, half-life, residence time, and total persistence of the active ingredient. In addition, an analysis was carried out, relating climatic conditions to the cumulative dissipation of pesticides. The results show an increase in the initial residues, half-life, and residence time of pesticides in the greenhouse. Otherwise, in the open field, the residues of the pesticides acetamiprid and azoxystrobin increased over the initial applications. Climatic conditions, mainly evapotranspiration during crop growing, involve the dissipation of pesticides in jalapeño pepper. The validation method demonstrated satisfactory parameters, aligning with the guidelines provided by the US EPA and SENASICA. All concentrations quantified in real samples were found to be below the MRLs, ensuring compliance with regulatory standards. Additionally, the dissipation kinetics played a critical role in elucidating key aspects such as residence times, latency periods, and marketing timelines for ensuring food safety. This kinetics provided essential insights into the behavior and persistence of the residues, contributing to a more comprehensive understanding of their dynamics in agricultural and commercial contexts. We believe these findings underscore the reliability and applicability of the method for monitoring pesticide residues in real-world scenarios. Full article

Sustainable agricultural practices are pivotal for environmental preservation and enhancing crop quality. Understanding soil nutrient levels is crucial in determining appropriate fertilizer application in agriculture production systems. In the 2022/23 agricultural season, an experiment that aimed to investigate the spatial distribution of nitrogen (N₂) fixation or absorption in fields cultivated with diverse crops was carried out in Mozambique. Three experimental fields were established, and the following crops were used—maize (local variety), soybean (SAN-BEIB variety), and cotton (ALBAR SZ9314 variety)—each measuring 83.35 m × 30 m. A sampling grid of 13.9 m × 10 m facilitated the collection of 24 composite soil samples per field, consisting of 5 sub-samples within 12 cells, taken at a depth of 0.0–0.20 m before planting and after harvesting, totaling 12 samples per period per field. Laboratory analysis employed the Kjeldahl method to determine total soil nitrogen levels. The Inverse Distance Weighted (IDW) method was used for mapping the spatial total soil nitrogen distribution. The results revealed distinct total soil nitrogen credit and debit patterns. Variations were notable between pre-planting and post-harvest analyses in maize and cotton, showcasing high absorption and minimal fixation. Contrary to expectations, soybeans exhibited high absorption and low fixation, challenging the determination of optimal crop rotation intervals. Quantitative results identified specific total soil nitrogen debit efficiencies of approximately 1692.29 kg ha⁻¹ in cotton and 1081.5 kg ha⁻¹ in maize, respectively, and a credit of 459.215 kg ha⁻¹ in soybeans. Despite discrepancies, this study serves as a foundational platform for future research. As the findings of this study advocate for continued crop rotation practices to bolster soil health and enhance nutrient utilization, it provides the first novel insights into nitrogen dynamics of global key crops in Mozambique, revealing significant variations in nitrogen fixation and absorption across different crop types and fields, which is crucial for informing tailored agricultural practices and soil fertility management strategies. Full article

Monitoring fungicide residues in orange fruits is vital, as fungicides for orange cultivation are increasingly used to prevent yield loss. At the same time, increasing restrictions are added by regulatory organizations. For facile on-site monitoring of the fungicide carbendazim (MBC), five ion-selective potentiometric sensors are proposed and compared. The first two sensors were prepared with a precipitation-based technique using molybdate (sensor 1) and tetraphenylborate (TPB) (sensor 2), respectively. Furthermore, two ionophore-based sensors were prepared using β-cyclodextrin as ionophore together with TPB (sensor 3) and tetrakis(4-chlorophenyl)borate (TpClPB) (sensor 4) as ion-exchanger. Further incorporation of multi-walled carbon nanotubes (MWCNTs) between the graphite rod and the sensing membrane of sensor 4 (sensor 5) further improved the stability and significantly lowered the limit of detection (LOD). Their performance was evaluated according to IUPAC recommendations, revealing linear response in the concentration range 1 × 10⁻⁴–1 × 10⁻² M, 1 × 10⁻⁵–1 × 10⁻² M, 1 × 10⁻⁵–1 × 10⁻³ M, 1 × 10⁻⁶–1 × 10⁻³ M, and 1 × 10⁻⁷–1 × 10⁻³ M with a Nernstian slope of 54.56, 55.48, 56.00, 56.85, and 57.34 mV/decade, respectively. The LOD values for the five sensors were found to be 7.92 × 10⁻⁵, 9.98 × 10⁻⁶, 9.72 × 10⁻⁶, 9.61 × 10⁻⁷, and 9.57 × 10⁻⁸ M, respectively. The developed potentiometric sensors were successfully applied to determine the residue and degradation rate of MBC in orange samples. After the researched fungicide was applied to the orange trees, the preharvest interval (PHI) could be calculated based on the MBC degradation kinetics determined in the tested orange samples. Full article

A double-cropping system is widely adopted in southern Korea, in which the sowing date of the second crop (soybean) can be delayed depending on the growth period of the first crop and weather conditions. Soybean yields may be reduced because of the shorter vegetative growth period and earlier flowering. This study examined soybean growth and yield responses as plant populations at a late planting date. A field experiment was conducted in the upland field at the Department of Southern Area Crop Science in Miryang, Gyeongsangnam-do, for two years (2022–2023) using four cultivars (Seonyu 2, Jungmo 3015, Seonpung, and Jangpung). A split-plot block design was used with three replications. The main plots had four sowing dates at 10-day intervals from 25 June to 25 July. The date of maturity was recorded, and the yield components and yield were examined after harvesting. The optimum planting population for maximizing the soybean yield with late planting was compared with the standard population result. To maintain pre- and post-crop yields and cultivate stable production, the sowing date limit for early maturing soybeans was July 15 and that for mid-maturing soybeans was July 5. The results highlight the potential to produce an economic soybean production level. Full article

Chloroisobromine cyanuric acid is a highly effective broad-spectrum systemic fungicide for disease control in agricultural crops. In this study, the degradation, residue levels, and potential dietary risks associated with the chloroisobromine cyanuric acid residues in two widely consumed crops, pepper and ginger, were evaluated through supervised field experiments conducted at 12 sites for pepper and 4 sites for ginger in China in 2021. A QuEChERS-LC-MS/MS method was established for quantifying cyanuric acid (CYA) in both crops. The method achieved a limit of quantification (LOQ) of 0.02 mg kg⁻¹ for ginger and 0.05 mg kg⁻¹ for pepper, with recovery rates ranging from 91% to 96% for ginger and 84% to 89% for pepper and the relative standard deviation of 2.9% to 11.2% for ginger and 2.8%~12.9% for pepper, respectively. The results indicated that CYA had half-lives ranging from 3.1 to 8.2 days in pepper, and the terminal CYA residues at harvest were all lower than 5 mg kg⁻¹, the maximum residue limit established in China. Furthermore, the chronic dietary risk exposure to chloroisobromine cyanuric acid in ginger and pepper, harvested at a pre-harvest interval of three days and at the normal harvesting time after the application of 50% chloroisobromine cyanuric acid soluble powder (SP), was 37.96%, which was much lower than 100%, indicating no significant health risks to the Chinese population. This study provides basic data for establishing the MRLs and serving as a reference for developing the analytical method applicable to CYA residues in different plant matrices. Full article

In the tea-planting process, insecticides are commonly combined, potentially prolonging the pre-harvest interval and heightening the risk of dietary exposure. This study focused on three frequently used insecticides in tea cultivation: thiamethoxam, bifenthrin, and dinotefuran, aiming to investigate their dissipation behaviors and associated dietary risks upon individual and simultaneous application. The dissipation kinetics of thiamethoxam, bifenthrin, and dinotefuran were successfully characterized by first-order kinetics, yielding respective half-lives of 5.44, 9.81, and 10.16 days. Upon joint application, the dissipation half-lives of thiamethoxam and bifenthrin were notably prolonged compared with their individual applications, resulting in final concentrations after 28 days that were correspondingly elevated by 1.41 and 1.29 times. Assessment of the dietary intake risk revealed that the chronic and acute risk quotients associated with thiamethoxam and bifenthrin escalated by 1.44–1.59 times following their combined application. Although dietary risks associated with Tianmuhu white tea, as determined by the exposure assessment model, were deemed acceptable, the cumulative risks stemming from pesticide mixtures across various dietary sources warrant attention. Molecular docking analyses further unveiled that thiamethoxam and bifenthrin competitively bound to glutathione S-transferase (GST) at amino acid residues, notably at the 76th GLU and the 25th PHE, pivotal in the metabolism and absorption of exogenous substances. Moreover, the interactions between P-glycoprotein and pesticides during transport and absorption were likely to influence dissipation behaviors post-joint application. This research offers valuable insights and data support for optimizing joint pesticide application strategies and assessing risks associated with typical pesticides used in tea cultivation. Full article

The fast and effective monitoring of agrochemical residues is essential for assuring food safety, since many agricultural products are sprayed with pesticides and commercialised without waiting for the pre-harvest interval. In this study, we investigated the use of spectral reflectance combined with principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) to evaluate the discrimination of fungicide-contaminated lettuces, considering three maximum residue limits (MRLs) [3.5, 5, and 7 mg carbon disulphide (CS₂) kg⁻¹]. The non-systemic Mancozeb fungicide (dithiocarbamate) was adopted in this research. Spectral reflectance (Vis/NIR) was measured by a hand-held spectrometer connected to a clip probe with an integrating sphere. The lettuce spectra were pre-treated (centring, standard normal variate, and first derivative) before data processing. Our findings suggest that PCA recognised inherent similarities in the fungicide-contaminated lettuce spectra, categorising them into two distinct groups. The PLS-DA models for all MRLs resulted in high accuracy levels, with correct discriminations ranging from 94.5 to 100% for the external validation dataset. Overall, our study demonstrates that spectroscopy combined with discriminating methods is a promising tool for non-destructive and fast discrimination of fungicide-contaminated lettuces. This methodology can be used in industrial food processing, enabling large-scale individual analysis and real-time decision making. Full article

The global cut flower industry, including lilies, represents a highly promising investment. Therefore, improving the quantity and quality of these commercially significant flower species is crucial. The objectives of this study were to (1) evaluate the influence of different pre-harvest chemical compounds on endogenous GA₃, phenol, flavonoids and total antioxidants levels on the leaf and petals parts of Longiflorum-Asiatic (Lilium × elegans cv. Cevennes, yellow) lily and to (2) assess the effect of these compound on the flower quality component. The study was conducted over two cycles in both greenhouse and laboratory settings. Lily bulbs were transplanted into 10 L pots and grown for 70 days. Treatments were applied by spraying twice with a five-day interval on the flowers still on the plants and not yet fully opened. The treatments included 8-hydroxyquinoline sulfate (8HQS) at 100, 200, and 400 mg L⁻¹; salicylic acid (SA) at 100 and 200 mg L⁻¹; SmartFresh™ at 1 and 2 mg L⁻¹; Harvista™ at 150 mg L⁻¹; GA₃ at 50 mg L⁻¹; and a control (water). The lily stems were harvested when one of the flowering buds began to open but was not fully opened. A post-harvest assessment was conducted in the laboratory at room temperature (20 ± 2 °C). The results showed that the lily leaf had a much higher endogenous concentration of GA₃ (256%) and lower concentrations of total phenols (22%), flavonoids (28%), and antioxidant activity (14%) when compared to flower petals. In addition, the foliar application of flower preservative compounds one week before harvesting significantly improved the endogenous levels of GA₃, total phenols, flavonoids, and antioxidants activity, especially SmartFresh™ at rate of 1 mg L⁻¹. In terms of flower quality, SmartFresh™, at rate of 1 mg L⁻¹, and 8-HQS, at rate of 200, had consistently higher vase lives compared to the control treatment across the two experimental cycles. Compared to the control, SmartFresh™ (the post-harvest ethylene control) increased the vase life of lily flowers by 35% at cycle 1 and 31% at cycle 2 while 8-HQS, at rate of 200 mg L⁻¹, increased the vase life by 21% and 15% at cycles 1 and 2, respectively. However, no significant effect was found in the petal flower color coordinates (L*, a* and b*) across the treatments. Overall, the foliar application of preservative compounds (such as SmartFresh™) at the pre-harvest stage potentially stimulates the endogenous levels of GA₃, total phenols, flavonoids, and antioxidants activity, leading to better improvements in post-harvest flower quality, specifically vase life. Full article

The QuEChERS method was adjusted to determine bifenthrin residues in grapes and grape leaves. Extraction and cleanup procedures were optimized to decrease co-extracted materials and enhance the detection of bifenthrin. The method was validated per the European Union (EU) Guidelines criteria. Accuracy ranged from 98.8% to 93.5% for grapes and grape leaves, respectively. Precision values were 5.5 and 6.4 (RSDr) and 7.4 and 6.7 (RSD_R) for grapes and grape leaves, respectively. LOQs (the lowest spiking level) were 2 and 20 µg/kg for grapes and grape leaves, respectively. Linearity as determination coefficient (R²) values were 0.9997 and 0.9964 for grapes and grape leaves, respectively, in a matrix over 1–100 µg/L range of analyte concentration. This was very close to the value in the pure solvent (0.9999), showing the efficiency of the cleanup in removing the co-extracted and co-injected materials; the matrix effect was close to zero in both sample matrices. Dissipation of bifenthrin was studied in a supervised trial conducted in a grapevine field during the summer of 2023 at the recommended dose and double the dose. Dissipation factor k values were 0.1549 and 0.1672 (recommended dose) and 0.235 and 0.208 (double dose) for grapes and grape leaves, respectively. Pre-harvest interval (PHI) was calculated for the Maximum Residue Limit (MRL) values of the EU database. Residues of bifenthrin were removed effectively from grapes using simple washing with tap water in a laboratory study. Residues reached the MRL level of 0.3 mg/kg in both washing treatments, running or soaking in tap water treatments for 5 min. Removal from leaves did not decrease residue levels to the MRL in grape leaves. Full article

This study presents a method for analyzing dimethomorph residues in lychee using QuEChERS extraction and HPLC-MS/MS. The validation parameters for this method, which include accuracy, precision, linearity, and recovery, indicate that it meets standard validation requirements. Following first-order kinetics, the dissipation dynamic of dimethomorph in lychee was determined to range from 6.4 to 9.2 days. Analysis of terminal residues revealed that residues in whole lychee were substantially greater than those in the pulp, indicating that dimethomorph residues are predominantly concentrated in the peel. When applied twice and thrice at two dosage levels with pre-harvest intervals (PHIs) of 5, 7, and 10 days, the terminal residues in whole lychee ranged from 0.092 to 1.99 mg/kg. The terminal residues of the pulp ranged from 0.01 to 0.18 mg/kg, with the residue ratio of whole lychee to pulp consistently exceeding one. The risk quotient (RQ) for dimethomorph, even at the recommended dosage, was less than one, indicating that the potential for damage was negligible. This study contributes to the establishment of maximum residue limits (MRLs) in China by providing essential information on the safe application of dimethomorph in lychee orchards. Full article