Does polyacrylamide-based adjuvant actually reduce primary drift of airborne pesticides?

Addition of konjac glucomannan improves spraying efficiency on fruits and vegetables: Effect of surface hydrophilicity and molecular weight

Biomacromolecules have attracted interest as spraying additives due to their degradability, renewability, and non-toxicity. However, microscopic mechanism of the biomacromolecules regulating the droplet behavior on fruits and vegetables is still unclear. In this study, konjac glucomannan (KGM) was used to improve the spraying efficiency and the fresh-keeping performance of tea polyphenols solution. KGM increased effective spreading ratio on hydrophilic surfaces and retention ratio of the main droplet on hydrophobic surfaces, thus improving spraying efficiency. Computational fluid dynamics and Brown dynamics simulations were implemented to investigate KGM behaviors during droplets colliding on hydrophilic and hydrophobic surfaces. Most KGM molecules extended and then collapsed in gradually weakened shear flow. Meanwhile, on the hydrophobic surface, most KGM molecules were continuously stretched by the unstable flow field. As the KGM extended, the kinetic energy of droplets converted into elastic energy stored in the KGM, promoting the stability of droplets on target surfaces and improving the spraying efficiency. The KGM molecular weight of 3.8 × 105 Da was optimal from the point of energy storage density. This study provides more understanding of the mechanism of biomacromolecules on spraying efficiency and guidance to develop biomass spraying additives for fruit and vegetable preservation.

Enhanced dosage delivery of pesticide under unmanned aerial vehicle condition for peanut plant protection: tank-mix adjuvants and formulation improvement

BACKGROUND

Suspension concentrate (SC) is one of the most widely used formulations for agricultural plant protection. With the rapid development of unmanned aerial vehicle (UAV) plant protection, the problems of spray drift, droplet rebound and poor wettability in the application of SC from UAVs have attracted wide attention. Although some tank-mix adjuvants have been used to enhance dosage delivery for UAV, their effects and mechanisms are not fully clear, and few formulations are specifically designed for UAV.

RESULTS

The type and concentration of tank-mix adjuvant affect the dosage delivery of SC. MO501 can significantly reduce DV<100μm , and inhibit droplet rebound on peanut leaves at concentrations ≥0.5%. Silwet 408 can achieve complete wetting and superspreading after adding ≥0.2% concentrations, but only ≥0.5% can inhibit rebound. XL-70 shows excellent regulation ability even at low concentration, and 0.2% concentration can simultaneously suppress impact and promote spreading. Besides, the formulation oil dispersion (OD) can significantly reduce the driftable fine fraction and inhibit rebound at dilution ratios of ≤250-fold, thus enhancing dosage delivery.

CONCLUSION

SC is prone to rebound on hydrophobic leaf surfaces and shows poor wetting and spreading properties. Appropriate types and concentrations of tank-mix adjuvants and formulation improvement are two effective strategies for improving the dosage delivery of pesticides, whereas the addition of inappropriate adjuvants may cause potential risks instead. These findings provide guidance for the rational selection of tank-mix adjuvants and potential applications of OD for UAV plant protection. © 2023 Society of Chemical Industry.

Airborne Pesticides-Deep Diving into Sampling and Analysis

The escalating utilization of pesticides has led to pronounced environmental contamination, posing a significant threat to agroecosystems. The extensive and persistent global application of these chemicals has been linked to a spectrum of acute and chronic human health concerns. This review paper focuses on the concentrations of airborne pesticides in both indoor and outdoor environments. The collection of diverse pesticide compounds from the atmosphere is examined, with a particular emphasis on active and passive air sampling techniques. Furthermore, a critical evaluation is conducted on the methodologies employed for the extraction and subsequent quantification of airborne pesticides. This analysis takes into consideration the complexities involved in ensuring accurate measurements, highlighting the advancements and limitations of current practices. By synthesizing these aspects, this review aims to foster a more comprehensive and informed comprehension of the intricate dynamics related to the presence and measurement of airborne pesticides. This, in turn, is poised to significantly contribute to the refinement of environmental monitoring strategies and the augmentation of precise risk assessments.

Zeolitic Imidazole Framework-90-Based Pesticide Smart-Delivery System with Enhanced Antimicrobial Performance

Multimodal antimicrobial technology is regarded as a promising strategy for controlling plant diseases because it enhances antimicrobial efficacy by blocking multiple pesticide-resistance pathways. In this work, a pH-responsive multimodal antimicrobial system was constructed based on ZIF-90 for the controlled release of kasugamycin (KSM). A series of physicochemical characterizations confirmed the successful fabrication of ZIF-90-KSM. The results indicated that the loading capacity of ZIF-90-KSM for KSM was approximately 6.7% and that the ZIF-90 nanocarriers could protect KSM against photodegradation effectively. The acid pH at the site of disease not only decompose the Schiff base bonds between KSM and ZIF-90, but also completely dissolved the nanocarriers. The simultaneous release of KSM and Zn²⁺ ions was able to achieve multimodal antimicrobial functions during disease occurs. A bioactivity survey indicated that ZIF-90-KSM had superior fungicidal activity and longer duration against Magnaporthe oryzae than KSM aqueous solution. In addition, the phytotoxicity assessment of ZIF-90-KSM on rice plants did not reveal any adverse effects. Therefore, ZIF-90-KSM prepared by Schiff base reaction has great potential for achieving synergistic antifungal functions and provides an eco-friendly approach to manage rice diseases.

Pesticides in ambient air, influenced by surrounding land use and weather, pose a potential threat to biodiversity and humans

Little is known about (i) how numbers and concentrations of airborne pesticide residues are influenced by land use, interactions with meteorological parameters, or by substance-specific chemo-physical properties, and (ii) what potential toxicological hazards this could pose to non-target organisms including humans. We installed passive air samplers (polyurethane PUF and polyester PEF filter matrices) in 15 regions with different land uses in eastern Austria for up to 8 months. Samples were analyzed for 566 substances by gas-chromatography/mass-spectrometry. We analyzed relationships between frequency and concentrations of pesticides, land use, meteorological parameters, substance properties, and season. We found totally 67 pesticide active ingredients (24 herbicides, 30 fungicides, 13 insecticides) with 10-53 pesticides per site. Herbicides metolachlor, pendimethalin, prosulfocarb, terbuthylazine, and the fungicide HCB were found in all PUF samplers, and glyphosate in all PEF samplers; chlorpyrifos-ethyl was the most abundant insecticide found in 93% of the samplers. Highest concentrations showed the herbicide prosulfocarb (725 ± 1218 ng sample^-1), the fungicide folpet (412 ± 465 ng sample^-1), and the insecticide chlorpyrifos-ethyl (110 ± 98 ng sample^-1). Pesticide numbers and concentrations increased with increasing proportions of arable land in the surroundings. However, pesticides were also found in two National Parks (10 and 33 pesticides) or a city center (17 pesticides). Pesticide numbers and concentrations changed between seasons and correlated with land use, temperature, radiation, and wind, but were unaffected by substance volatility. Potential ecotoxicological exposure of mammals, birds, earthworms, fish, and honeybees increased with increasing pesticide numbers and concentrations. Human toxicity potential of detected pesticides was high, with averaged 54% being acutely toxic, 39% reproduction toxic, 24% cancerogenic, and 10% endocrine disrupting. This widespread pesticide air pollution indicates that current environmental risk assessments, field application techniques, protective measures, and regulations are inadequate to protect the environment and humans from potentially harmful exposure.

A fuzzy knowledge-based model for assessing risk of pesticides into the air in cropping systems

Pesticide use in current cropping systems has become a key input to improve productivity. However, their potential risk to nature demands tools for designing a sustainable use. In this work, a fuzzy knowledge-based model was developed for assessing risk of pesticides into the air. The model was based on fuzzy logic theory which provides a means for representing uncertainty by including knowledge about different processes related to pesticide dynamics using functions, control rules and logical inference systems. All these elements were built through a literature review. Results from the sensitivity analysis on the final model structure showed that the Henry's law constant was the most influential input variable related to the active ingredient identity, while the most influential management and environmental input variables on the pesticide air risk values were the droplet size together with the application method and the current wet bulb temperature depression value, respectively. Results from an independent model validation showed a significant goodness-of-fit between the simulated risk of drift and volatilization and the observed values under experimental conditions. Long-term simulations in a real soybean production system in Argentina showed results of drift reduction in post-emergence conditions of the crop under aerial application condition, and a significant effect of the identity of the active ingredient in the risk values. Simulated risk values from the developed model allow to identify ex ante the combination of agronomic decisions, together with environmental conditions that can reduce the risk of pesticides in the air in real production systems. Further combination with ecotoxicological classification tools should improve pesticide use assessment in agricultural systems.

Reducing pesticide spraying drift by folate/Zn2+ supramolecular hydrogels

BACKGROUND

The purpose of this study was to use folic acid and zinc nitrate to construct a biocompatible supramolecular hydrogel loaded with the herbicide dicamba as an ultra-low-volume spray formulation. The drift potential of the hydrogel was studied by simulating the field environment in a wind tunnel.

RESULTS

The three-dimensional network structure of the successfully prepared dicamba hydrogel system was observed using cryo-scanning electron microscopy. A rheological study of the dicamba hydrogel showed that it has shear-thinning and self-healing properties. Using a laser particle size analyzer, it was shown that the droplet size of the dicamba gel (approximately 100 μm) was significantly larger than that of the control group water and dicamba-KOH droplets. Droplet collectors and water-sensitive papers were arranged in the wind tunnel to evaluate the drift-reduction performance of the dicamba gel. Compared with dicamba-KOH aqueous solution, dicamba gel has a good effect in reducing drift.

CONCLUSION

This hydrogel containing no organic solvents showed biocompatibility and biodegradability due to its natural and readily available raw materials. The main way in which hydrogels reduce drift is by increasing the droplet size and this is due to the three-dimensional network structure inside the gel. This research provides a new strategy to reduce spray drift from the perspective of pesticide formulation, and also has prospects for the application of supramolecular hydrogels in agriculture.