thiophanate and pyrachlostrobin

Topics: Fungicides, Industrial; Glycine max; Kentucky; Thiophanate; United States

The highly heterogeneous nature of

Topics: Biphenyl Compounds; Botrytis; Cyprus; Drug Resistance, Fungal; Fragaria; Fungicides, Industrial; Greece; Niacinamide; Organic Agriculture; Plant Diseases; Strobilurins; Thiophanate

Winter is the key period for the control of apple diseases, and fungicides are needed to protect the trunk or main branches. Fungicide residue in apple tree bark is an important basis for the action of the pesticide, but there are no reports on analytical methods or dissipation patterns. In this work, thiophanate-methyl, carbendazim, tebuconazole and pyraclostrobin were selected as typical fungicides and a new QuEChERS-HPLC-VWD(QuEChERS extraction followed by high-performance liquid chromatography detection with a variable wavelength detector) analytical method was developed to estimate their residue kinetics in apple tree bark during the winter months. In the pretreatment step, the sorbent for the clean-up of extracts was optimized as 60 mg/ml primary secondary amine and a gradient-elution model followed by a variable wavelength detection was developed for instrumental analysis. Then this method was validated and applied to the analysis of apple tree bark samples with the linearity range of 0.010-50.00 mg/L, quantification limit range of 0.028-0.080 mg/kg and recovery range of 86.1-101.4%. The dissipation kinetics of thiophanate-methyl and pyraclostrobin could be described by the first-order and two-phase kinetics models, respectively. For carbendazim and tebuconazole, two new models were developed to describe their residue kinetics.

Topics: Benzimidazoles; Carbamates; Chromatography, High Pressure Liquid; Fungicides, Industrial; Linear Models; Malus; Pesticide Residues; Plant Bark; Reproducibility of Results; Sensitivity and Specificity; Spectrophotometry, Ultraviolet; Strobilurins; Thiophanate; Triazoles

Incidence of blossom blight and Botrytis fruit rot (BFR), caused by Botrytis cinerea, on two southern highbush blueberry cultivars was evaluated in several blueberry fields grown in the vicinity (BB-Str

Topics: Amides; Biphenyl Compounds; Blueberry Plants; Botrytis; Captan; Drug Resistance, Fungal; Fragaria; Fungicides, Industrial; Niacinamide; Phenotype; Plant Diseases; Pyrazoles; Pyrimidines; Strobilurins; Thiophanate; Thiophenes

Topics: Benzimidazoles; Carbamates; Chromatography, High Pressure Liquid; Chromatography, Liquid; Citrus; Pesticide Residues; Pyrazoles; Soil; Strobilurins; Tandem Mass Spectrometry; Thiophanate

Previous research has shown that Botrytis cinerea isolates with resistance to multiple chemical classes of fungicides exist in eastern strawberry fields. In this study, the fungicide resistance profiles of 2,130 isolates from flowers of commercial strawberry fields located in multiple states was determined over four consecutive strawberry production seasons. Producers were asked to alternate single-site fungicides that were considered low risk in their specific location based on resistance monitoring results in their fields. This recommendation led to an increase of chemical class diversity used in the spray programs. Results indicated that simultaneous resistance in individual isolates to two, three, four, five, six, and seven classes of fungicides increased over time. The increase in chemical class resistances within isolates was likely due to a process we termed "selection by association", where fungicide resistance traits were often linked to the trait being selected rather than the selectable trait itself. Data analysis also indicated that the odds were highest for isolates resistant to one chemical class (1CCR) to be resistant to thiophanate-methyl; for 2CCR isolates to be resistant to thiophanate-methyl and pyraclostrobin; and for 3CCR isolates to be resistant to thiophanate-methyl, pyraclostrobin, and either cyprodinil or fenhexamid. We hypothesize that the more chemical classes are used in a spray program, the faster isolates will be selected with increasing numbers of chemical class resistances by virtue of selection by association if such isolates preexist in the population.

Topics: Botrytis; Carbamates; Drug Resistance, Fungal; Fragaria; Fungicides, Industrial; Phenotype; Plant Diseases; Pyrazoles; Pyrimidines; Strobilurins; Thiophanate