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A series of isothiazole, 1,2,3-thiadiazole, and thiazole-based cinnamamide morpholine derivatives were rationally designed, synthesized, characterized, and evaluated for their fungicidal activities. Bioassay indicated that a combination of 3,4-dichloroisothiazole active substructures with cinnamamide morpholine lead to significant improvement of in vivo antifungal activities of the target compounds; among them, compound 5a exhibited good fungicidal activity against Pseudoperonspera cubensis in vivo with an inhibition rate of 100% at 100 μg/mL. A field experiment indicated that the difference of efficacy between 5a (75.9%) and dimethomorph (77.1%) at 37.5 g ai/667 m 2 was not significant; and 5a also exhibited good activity against Botrytis cinerea by triggering accumulation of PAL and NPR1 defense-related gene expression and the defense associated enzyme phenylalanine ammonia-lyase (PAL) expression on cucumber, rather than direct inhibition. These findings strongly supported that 3,4-dichloroisothiazole containing cinnamamide morpholine 5a not only showed good fungicidal activity against P. cubensis but also exhibited plant innate immunity stimulation activity as a promising fungicide candidate with both fungicidal activity and systemic acquired resistance.

Due to their unique properties, copper-based nanopesticides are emerging in the market. Thus, understanding their effect on crop plants is very important. Metabolomics can capture a snapshot of cellular metabolic responses to a stressor. We selected maize and cucumber as model plants for exposure to different doses of Cu(OH) 2 nanopesticide. GC-TOF-MS-based metabolomics was employed to determine the metabolic responses of these two species. Results revealed significant differences in metabolite profile changes between maize and cucumber. Furthermore, the Cu(OH) 2 nanopesticide induced metabolic reprogramming in both species, but in different manners. In maize, several intermediate metabolites of the glycolysis pathway and tricarboxylic acid cycle (TCA) were up-regulated, indicating the energy metabolism was activated. In addition, the levels of aromatic compounds (4-hydroxycinnamic acid and 1,2,4-benzenetriol) and their precursors (phenylalanine, tyrosine) were enhanced, indicating the activation of shikimate-phenylpropanoid biosynthesis in maize leaves, which is an antioxidant defense-related pathway. In cucumber, arginine and proline metabolic pathways were the most significantly altered pathway. Both species exhibited altered levels of fatty acids and polysaccharides, suggesting the cell membrane and cell wall composition may change in response to Cu(OH) 2 nanopesticide. Thus, metabolomics helps to deeply understand the differential response of these plants to the same nanopesticide stressor.

Because of its relatively high water solubility and mobility, 2,4-dichlorophenoxy acetic acid (2,4-D) has a high leaching potential threatening the surface water and groundwater. Controlled release formulations of 2,4-D could alleviate the adverse effects on the environment. In the present study, positive-charge functionalized mesoporous silica nanoparticles (MSNs) were facilely synthesized by incorporating trimethylammonium (TA) groups onto MSNs via a postgrafting method. 2,4-D sodium salt, the anionic form of 2,4-D, was effectively loaded into these positively charged MSN-TA nanoparticles. The loading content can be greatly improved to 21.7% compared to using bare MSNs as a single encapsulant (1.5%). Pesticide loading and release patterns were pH, ionic strength and temperature responsive, which were mainly dominated by the electrostatic interactions. Soil column experiments clearly demonstrated that MSN-TA can decrease the soil leaching of 2, 4-D sodium salt. Moreover, this novel nanoformulation showed good bioactivity on target plant without adverse effects on the growth of nontarget plant. This strategy based on electrostatic interactions could be widely applied to charge carrying agrochemicals using carriers bearing opposite charges to alleviate the potential adverse effects on the environment.

Pesticides are chemical or biological substances to control pests and protect the crop yield. Most pesticides suffering from large amounts of losses in the environment lead to damage of ecological systems and food pollution. To reduce their losses and increase the utilization rate, we have developed bioinspired mussel avermectin nanoparticles [P(St-MAA)-Av-Cat] with strong adhesion to crop foliage by the emulsion-solvent evaporation method and chemical modification. They were near spheres with a diameter of around 120 nm. They displayed remarkable high avermectin content of more than 50% (w/w) and presented excellent storage stability as well as continuous sustained release. The photosensitive avermectins loaded were highly improved against ultraviolet light. Meanwhile, the retention rate of P(St-MAA)-Av-Cat on the crop foliage surfaces was significantly increased. As a result, the indoor toxicity of P(St-MAA)-Av-Cat was highly enhanced. The adhesive property strongly depended upon the functional groups on the nanoparticle surface. The multimodal binding mode of P(St-MAA)-Av-Cat to the crop foliage surface resulted in stronger adhesion and a longer retention time.

Downy mildew is one of the most highly destructive of the diseases that cause damage to fruits and vegetables. Because of the continual development of resistance, it is important to discover new fungicides with different modes of action from existing fungicides for the control of downy mildew. This study is a continuation of our previous work on the novel pyrimidinamine lead compound, 9, and includes field trials for the identification of the optimal candidate. A new compound, 1c, was obtained, which gave a lower EC 50 value (0.10 mg/L) against downy mildew than lead compound 9 (0.19 mg/L) and the commercial fungicides diflumetorim, dimethomorph, and cyazofamid (1.01-23.06 mg/L). Compound 1c displayed similar broad-spectrum fungicidal activity to compound 9 but better field efficacy than compound 9, cyazofamid, and flumorph. The present work indicates that pyrimidinamine compound 1c is a candidate for further development as a commercial fungicide for the control of downy mildew.

The pyrimidinamine diflumetorim is an ideal template for the discovery of agrochemical lead compounds due to its unique mode of action, novel chemical structure, and lack of reported resistance. To develop a new pyrimidinamine fungicide effective against cucumber downy mildew (CDM), a series of new pyrimidinamine derivatives containing an aryloxy pyridine moiety were designed and synthesized by employing the recently reported intermediate derivatization method (IDM). The structures of all compounds were identified by 1 H NMR, elemental analyses, HRMS, and X-ray diffraction. Bioassays demonstrated that some of the title compounds exhibited excellent fungicidal activities against CDM. Compound 9 gave the best activity (EC 50 = 0.19 mg/L), which is significantly better than the commercial fungicides diflumetorim, flumorph, and cyazofamid. The relationship between structure and fungicidal activity of the synthesized pyrimidinamines was explored. The study showed that compound 9 is a promising fungicide candidate for further development.

The iron oxyallyl carbocation generated from 2,7-dibromocycloheptanone was induced to undergo [4 + 3] cycloaddition reactions with various furans, affording a series of 12-oxatricyclo-[4.4.1.1(2,5)]-dodec-3-en-11-one adducts. Similar methodology was used to prepare two additional cycloadducts using menthofuran and two homologous aliphatic dibromoketones. Dipolar cycloaddition of ozone to the adducts afforded the corresponding secondary ozonides (i.e., 1,2,4-trioxolanes) in variable yields. Ozonides were investigated by quantum mechanics at the B3LYP/6-31+G* level to study structural features including close contacts which may be responsible for enhancing ozonide stability. The effect of these ozonides and their corresponding precursor cycloadducts upon radicle growth of both Sorghum bicolor and Cucumis sativus was evaluated at 5.0 x 10(-4) mol L(-1). The most active cycloadducts and ozonides were also evaluated against the weed species Ipomoea grandifolia and Brachiaria decumbens, and the results are discussed. Compared to ozonides previously synthesized in our laboratory, the new ozonides described herein present improved plant growth regulatory activity.

Brassinosteroids (BRs) are known to protect crops from the toxicity of herbicides, fungicides and insecticides. It is shown here that application of 24-epibrassinolide (EBR) accelerated metabolism of various pesticides and consequently reduced their residual levels in cucumber ( Cucumis sativus L). Chlorpyrifos, a widely used insecticide, caused significant reductions of net photosynthetic rate (Pn) and quantum yield of PSII (Phi(PSII)) in cucumber leaves. EBR pretreatment alleviated the declines of Pn and Phi(PSII) caused by chlorpyrifos application, and this effect of EBR was associated with reductions of chlorpyrifos residues. To understand how EBR promotes chlorpyrifos metabolism, the effects of EBR on activity and expression of enzymes involved in pesticide metabolism were analyzed. EBR had a positive effect on the activation of glutathione S-transferase (GST), peroxidase (POD), and glutathione reductase (GR) after treatment with chlorpyrifos, although the effect on GR was attenuated at later time points when plants were treated with 1 mM chlorpyrifos. In addition, EBR enhanced the expression of P450 and MRP, which encode P450 monooxygenase and ABC-type transporter, respectively. However, the expression of GST was consistently lower than that of plants treated with only chlorpyrifos. Importantly, the stimulatory effect of EBR on pesticide metabolism was also observed for cypermethrin, chlorothalonil, and carbendazim, which was attributed to the enhanced activity and genes involved in pesticide metabolism. The results suggest that BRs may be promising, environmentally friendly, natural substances suitable for wide application to reduce the risks of human and environment exposure to pesticides.

A short and efficient approach to a range of new chiral and achiral functionalized (E)-enaminopyran-2,4-diones starting with commercially available dehydroacetic acid is described. The phytotoxic properties of these (E)-enaminopyran-2,4-diones were evaluated by their ability to interfere with the growth of Sorghum bicolor and Cucumis sativus seedlings. A different sensitivity of the two crops was evident with the (E)-enaminopyran-2,4-diones. The most active compounds were also tested against two weeds, Ipomoea grandifolia and Brachiaria decumbens. To the best of our knowledge, this is the first report describing enaminopyran-2,4-diones as potential plant growth regulators.

The [4 + 3] cycloaddition of the proper furans with the oxyallyl cation, generated in situ from 2,4-dibromopentan-3-one, produced a series of 8-oxabicyclo [3.2.1]oct-6-en-3-ones. Exposure of the oxabicycles to ozone afforded the corresponding 8,9,10,11-tetraoxatricyclo[5.2.1.1 (2,6)]undecan-4-ones in variable yields (7-100%). The phytotoxic properties of these ozonides (or 1,2,4-trioxolanes) and their oxabicycle precursors were evaluated as the ability to interfere with the growth of Sorghum bicolor and Cucumis sativus seedlings. Among oxabicycles, the highest inhibitory activity was shown by compounds possessing a alpha,beta-unsaturated carbonyl moiety. A differential sensitivity of the two crops was evident with ozonides. The most active compounds were also tested against the weed species Ipomoea grandifolia and Brachiaria decumbens. To the best of our knowledge, this is the first article describing ozonides as potential herbicides.

Based on the carbamoyl triazole herbicide Cafenstrole, 12 novel selenium-containing compounds were designed and synthesized. All of the compounds were characterized and confirmed by IR, 1H NMR, and high-resolution mass spectroscopy. The bioassay tests showed that some of the compounds (C2, C4, C(7-8), and C12) exhibited good inhibitory activity against cucumber (Cucumis sativus L.) and semen euphorbiae (Leptochloa chinensis N.). Especially, compound C6 inhibited the growth of cucumber and semen euphorbiae by >90% at a concentration of 1.875 microg/mL, and the inhibition of the compound on the rice (Oryza sativa L.) was only 8.3% at a concentration of 7.5 microg/mL, which indicated a higher selectivity between weed and rice than that shown by Cafenstrole.