Distribution of Emamectin Benzoate Granules in Maize Plants by Broadcasting into Maize Leaf Whorls.

Good control effects on fall armyworm (FAW) can be obtained by broadcasting emamectin benzoate (EB) granules into maize leaf whorls. However, the distribution of EB in maize plants is not clear. In this study, EB granules were prepared by the rotating granulation method, and the granules were characterized using a Fourier transform infrared spectrometer. The behavior of EB granules in water was observed using a microscope, and in vitro release of EB from granules was also studied. A method for the determination of EB in maize plants, old leaves, grains, and cobs was established by using ultra-performance liquid chromatography-tandem mass spectrometry. The results showed that EB was loaded in granules successfully, and the granules disintegrated slowly in water, so the release of granules could be regulated using various water contents. The prepared EB granules were qualified and stable. The field experiment showed that the concentration of EB in maize leaf whorls could be maintained above 0.23 mg·kg-1 within 3 days after broadcasting EB granules. This ensured that FAW could be killed in a short time. Then, EB gradually transferred to the old leaves. After 21 days of application, the content of EB in the old leaves was 0.07 mg·kg-1, which has long-time control effects on FAW. The control effects of the three doses of granules against Spodoptera frugiperda were higher than 78% after 14 days of application. At the tested dosage, no phytotoxicity to crops was observed. At harvest, neither the maize grain nor the cobs had EB content. New controlled formulations to S. frugiperda were developed and will be suitable for application in mountainous areas where the lack of water resources is a factor.

Controlled-release alginate-bentonite polymer gel granules of emamectin benzoate and control efficacy against Spodoptera frugiperda.

BACKGROUND: The fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), is known to cause large agricultural production losses. Emamectin benzoate is one of the most effective insecticides to control this pest; however, its effective time is not sufficiently long to control FAW. Therefore, it is important that new controlled insecticide formulations with new application methods are developed. RESULTS: A series of emamectin benzoate polymer gel granules were prepared with sizes ranging from 0.95 to 1.5 mm. As the bentonite content increased, the release rate decreased. The cumulative release process of emamectin benzoate mainly depends on the cracks in the surface of the granules, and the release rate can be described by non-Fickian and Fickian diffusion, which are closely related to the water content. By spreading the developed polymer gel granules into maize leaf whorls, the control effect reached 83% after 21 days in field trials. CONCLUSION: A novel polymer gel granule was developed that can effectively regulate emamectin benzoate release. By broadcasting polymer gel granules into maize leaf whorls, significant control efficacy against FAW can be obtained, and this could potentially be used for the effective control of FAW. © 2022 Society of Chemical Industry.

Application of thifluzamide alters microbial network structure and affects methane cycle genes in rice-paddy soil.

Thifluzamide is an effective agent for controlling rice sheath blight and has a long half-life in soil. However, the effects of thifluzamide on the abundance of microbes harboring methane-cycle genes and soil microbial community assembly patterns are not well known. Thus, we conducted a three-month indoor mesocosm experiment to ascertain the effects of thifluzamide (0.05, 0.5, and 5 mg kg-1 soil; 0.05 mg kg-1 soil being recommended) on bacterial and archaeal community structure and on the abundance of methanogen genes using two typical paddy soils: sandy soil from Hangzhou (HZ) and loam sandy soil from Jiansanjiang (JSJ). The effects of thifluzamide on soil microorganisms were related to soil type. In JSJ loam sandy soil, thifluzamide significantly increased bacterial α diversity after 7-30 d and archaeal α diversity at 30 and 60 d. In HZ sandy soil, however, α diversity did not change significantly. Network analysis showed that thifluzamide-treated soils possessed more complex networks with more total nodes and links, a higher average degree of connectivity, and more keystone species. Thifluzamide application increased the number of keystone species associated with methane production in both types of paddy soil. A relatively greater number of modules were significantly negatively correlated with mcrA abundance in the HZ T10 network, but more modules were positively correlated with mcrA abundance in the JSJ T100 network. The half-life of thifluzamide varied for the different doses, i.e., from 152.0 to 419.6 d. The results reveal that methane-cycle genes, soil microbiome assembly, and interactions among microbial species all change in response to thifluzamide stress.

Uptake and Distribution of Fenoxanil-Loaded Mesoporous Silica Nanoparticles in Rice Plants.

Mesoporous silica nanoparticles (MSNs) can be used as carriers to deliver pesticides into plants, which is considered to be one method of improving the efficacy of pesticide usage in agricultural production. In the present work, MSNs with an average diameter of 258.1 nm were synthesized and loaded with Fenoxanil. The structure of the nanocarriers was observed by scanning electron microscopy. The loading content of Fenoxanil-loaded MSNs was investigated. After rice plants in a hydroponic system were treated with loaded MSNs, the concentrations of Fenoxanil in different samples were determined using high-performance liquid chromatography⁻tandem mass spectrometry. The results suggested that rice plants can absorb MSNs from water through their roots, and the dosage has almost no effect on the distribution of Fenoxanil in rice plants. The application of pesticide-loaded nanoparticles in a hydroponic system poses a low risk of Fenoxanil accumulation in rice.

Synthesis and antifungal activities of 5-(3,4,5-trimethoxyphenyl)-2-sulfonyl-1,3,4-thiadiazole and 5-(3,4,5-trimethoxyphenyl)-2-sulfonyl-1,3,4-oxadiazole derivatives.

Starting from the key intermediate 5-(3,4,5-trimethoxyphenyl)-1,3,4-thiadiazole-2-thiol (4) or the oxadiazole analogue (5), the title compounds 9 and 10 are synthesized by a two-step process. Thioetherification reaction of 4 or 5 with an organic halide catalyzed by indium or indium tribromide first affords appropriate sulfide 7 or 8, which is then converted into title compounds 9 or 10 by hydrogen peroxide oxidation catalyzed by ammonium molybdate in ionic liquid [bmim]PF6. The structures are unequivocally confirmed by spectroscopic (IR, 1H and 13C NMR) data and elemental analyses. The structures of 8d and 10q are further established by X-ray crystallographic diffraction analysis. The compounds have been shown to be fungicidally active. Title compounds 10i and 10j can inhibit mycelia growth by approximately 50% (EC50) at 2.9-93.3 microg/mL in vitro against 10 kinds of fungi.