查看更多>>摘要：? 2021Biosolarization is an alternative to chemical fumigation that couples solarization and organic amendments to control diseases by increasing temperature and microbial activity. A field study was conducted to evaluate the efficacy of biosolarization, using almond processing residues from two varieties, to control propagules of Fusarium oxysporum f. sp. lactucae, the causal agent of Fusarium wilt of lettuce. Peak soil temperatures of solarized and biosolarized soils were 6–15 °C higher than control soils, and biosolarized soils experienced 1 to 3 °C higher temperatures on average and 10 to 27°C-day higher cumulative temperatures than soil solarized without amendment. Residues were high in endogenous organic acids, between 144 and 298 mM combined acetic, lactic, succinic, and butyric acids. After eight days of treatment, solarized soils only reduced the population of Fusarium oxysporum f. sp. lactucae by 9% compared to the average non-treated non-amended control plots; whereas soils solarized and amended with residues from pollinator varieties of almonds showed a greater pathogen reduction of 63%. In this instance, Fusarium wilt had no effect on plant health due to low pressure and moderate innate plant resistance. Soils amended with nonpareil residues had similar lettuce biomass and health scores to untreated plots, but lower health scores than the solarized treatments. This may be due to residual organic acids detected in biosolarized plots 3–4 weeks after treatments (1–57 mM), which significantly correlated to poor lettuce health score. Roughly, one year after soil treatment, solarized plots continued to out-perform pollinator-residue amended plots. Germination assays indicate biosolarization outcomes may be improved with increased aerobic remediation time.
查看更多>>摘要：? 2021 Elsevier LtdIn Brazil, there are some commercial products composed of metalaxyl-M that can be used as seed treatment of soybean. Metalaxyl-M is a fungicide with efficacy against oomycetes, however, the concentrations and recommended doses of commercial products are not very effective. The objective of this study was to investigate the effect of increasing the dose of commercial products composed of metalaxyl-M for controlling root rot of soybean caused by two species of Globisporangium (G. irregulare and G. sporangiiferum var. ultimum) The treatments were arranged in a factorial scheme of 3 fungicides (Apron, Maxim Advanced and Maxim Quattro) x 7 doses (0.000, 0.003, 0.006, 0.012, 0.018, 0.024, 0.030 mg of metalaxyl-M per seed) x 2 soybean cultivars (‘DM57i52’ and ‘NEO530’). Separate experiments were conducted for each species of Globisporangium. There was a significant effect of the doses on the reduction of root rot severity for both soybean cultivars. The response of root rot severity according to the doses followed either logistic or Weibull regression models. The effective concentrations of metalaxyl-M that reduced 50%, 70% and 90% of root rot severity for ‘NEO530’ were higher than ‘DM57i52’ independently of the product applied. Thus, it can be concluded that the increase in fungicide dose compared to what is already used in Brazil, can promote greater levels of control of root rot caused by G. ultimum var. sporangiiferum and G. irregulare in soybean.
查看更多>>摘要：? 2021 Elsevier LtdFlonicamid (N-cyanomethyl-4-trifluoromethylnicotinamide) is a novel systemic insecticide that shows high insecticidal toxicity against sap-sucking pests. However, little is known about the sublethal effects of flonicamid on melon aphid, Aphis gossypii Glover, a serious insect pest of many vegetables. Herein, the toxicity of flonicamid to A. gossypii was determined using the leaf-dipping method, and the sublethal effects of this insecticide on biological traits of A. gossypii were evaluated using age-stage, two-sex life table method. The results showed that the LC50 value of flonicamid to A. gossypii adults was 7.177 mg L?1. The sublethal (LC5) and low lethal (LC15) concentrations of flonicamid reduced the fecundity of the F0 generation aphids. Moreover, the intrinsic rate of increase (r) and finite rate of increase (λ) of F1 generation were also significantly decreased in the flonicamid treatment groups, while the mean generation time (T) of the F1 generation was significantly prolonged compared to the control. In addition, the expression levels of juvenile hormone epoxide hydrolase (JHEH), vitellogenin (Vg), and ultraspiracle protein (USP) significantly increased in surviving adult aphids that were exposed to LC5 and LC15 of flonicamid in the F0 generation. The data demonstrate that sublethal and low lethal concentrations of flonicamid could suppress the growth of A. gossypii, and the differential expression of development- and reproduction-related genes might be involved in the sublethal effects of flonicamid on A. gossypii.
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