pyrachlostrobin and dithianone

The yam (Dioscorea spp.) is widely cultivated in China. The degradation of dithianon and pyraclostrobin in yams with different planting and processing treatments was investigated in this article. An analytical method for two pesticides in yam and yam plant was developed, and recoveries were between 77% and 93%, with relative standard deviations from 0.8% to 7.4%, respectively. On the basis of this method, half-lives for plants grown on stakes versus plants grown without stakes were compared. The results indicated that the half-life for pesticide residues for plants grown on stakes versus plants grown without stakes differed as 6.7 versus 3.1 days for dithianon and 5.4 versus 5.2 days for pyraclostrobin. Dithianon was significantly influenced by planting mode because of its low stability under sunlight. The processing factors of various processing treatments (hot air-drying, vacuum freeze-drying, microwave vacuum-drying, infrared-drying, steaming, and boiling) were all <1, indicating that those processes can reduce residues of two pesticides at different levels. Significant amounts of residues were removed during the boiling treatment, whereas the others showed less effect.

Topics: Anthraquinones; China; Chromatography, High Pressure Liquid; Colletotrichum; Crop Production; Dioscorea; Food Handling; Fungicides, Industrial; Mass Spectrometry; Plant Diseases; Strobilurins

A study of the in vitro sensitivity of 10 isolates of Didymella applanata to copper hydroxide, dithianon, fluazinam, tebuconazole and pyraclostrobin, was conducted. The isolates were derived from diseased raspberry canes sampled during 2013 at five localities in western part of Serbia, known as the main raspberry growing region of the country. Prior to sensitivity testing experimental conditions for radial growth assay were optimized. The results showed that the temperature of 22 °C, oatmeal agar medium and 12/12 hrs light/ darkness light regimen provided the best conditions for sensitivity tests. Most of D. applanata isolates were sensitive to the tested fungicides. The narrowest range of EC50 values was recorded for tebuconazole (1.42-2.66 mg L(-1)). The widest range of EC50 values was obtained for pyraclostrobin, ranging from 0.17 mg L(-1) to 55.33 mg L(-1). The EC50 values for the studied isolates were 39.48-51.19 mg L(-1) for copper hydroxide, 12.12-18.73 mg L(-1) for dithianon and 5.72-42.56 mg L(-1) for fluazinam. According to resistance factor values, all D. applanata isolates were sensitive to copper hydroxide, dithianon and tebuconazole. Among tested isolates, six were highly resistant to pyraclostrobin (RFs in the range of 207.1-325.5) and two moderately resistant to fluazinam (RFs were 3 and 7.4), respectively.

Topics: Aminopyridines; Anthraquinones; Ascomycota; Carbamates; Copper; Fungicides, Industrial; Hydroxides; Microbial Sensitivity Tests; Plant Diseases; Pyrazoles; Rubus; Serbia; Strobilurins; Triazoles