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Research Article

Persistence of Elemental Sulfur Spray Residue on Grapes during Ripening and Vinification

Misha T. Kwasniewski, Gavin L. Sacks, Wayne F. Wilcox
Am J Enol Vitic.  2014  65: 453-462  ; DOI: 10.5344/ajev.2014.14027

Article Figures & Data

Figures

  • S0 residues on Chardonnay (2009 and 2010) and Riesling (2011) clusters at harvest. Data are grouped by days before harvest of the final S0 application, with each bar representing the mean value for a five-cluster sample taken from each of six treatment sampling units (2/replicate plot). Means not labeled with a common letter are significantly different (p < 0.05). No residue was detected on any samples from the control treatment (no S0 applied, data not shown). The * denotes a treatment which received micronized sulfur at 4.48 kg/ha in the first three applications and 2.24 kg/ha in the final two.
    Figure 1

    S0 residues on Chardonnay (2009 and 2010) and Riesling (2011) clusters at harvest. Data are grouped by days before harvest of the final S0 application, with each bar representing the mean value for a five-cluster sample taken from each of six treatment sampling units (2/replicate plot). Means not labeled with a common letter are significantly different (p < 0.05). No residue was detected on any samples from the control treatment (no S0 applied, data not shown). The * denotes a treatment which received micronized sulfur at 4.48 kg/ha in the first three applications and 2.24 kg/ha in the final two.

  • Elemental sulfur (S0) residue on Chardonnay grape clusters sampled throughout the 2010 growing season. Sequential sprays of commercial sulfur formulations were applied starting 50 days before harvest and continuing at ~2-week intervals, ceasing a variable number of days before harvest on designated vines as denoted on the x-axis. S0 residue data are grouped by sulfur treatment, with each bar representing the mean value for a five-cluster sample taken from each of six treatment sampling units (2/replicate plot). The legend denotes the number of days before harvest that samples were obtained, and arrows signify a S0 application within the sampling period for each group of vines. No residue was detected on samples from the control treatment (no S0 applied, data not shown).
    Figure 2

    Elemental sulfur (S0) residue on Chardonnay grape clusters sampled throughout the 2010 growing season. Sequential sprays of commercial sulfur formulations were applied starting 50 days before harvest and continuing at ~2-week intervals, ceasing a variable number of days before harvest on designated vines as denoted on the x-axis. S0 residue data are grouped by sulfur treatment, with each bar representing the mean value for a five-cluster sample taken from each of six treatment sampling units (2/replicate plot). The legend denotes the number of days before harvest that samples were obtained, and arrows signify a S0 application within the sampling period for each group of vines. No residue was detected on samples from the control treatment (no S0 applied, data not shown).

  • S0 residues on Riesling grape clusters sampled throughout the 2011 growing season. Sequential sprays of commercial sulfur formulations were applied starting 81 days before harvest and continuing at ~2-week intervals, ceasing a variable number of days before harvest on designated vines as denoted on the x-axis. S0 residue data are grouped by sulfur treatment, with each bar representing the mean value for a five-cluster sample taken from each of six treatment sampling units (2/replicate plot). The legend denotes the number of days before harvest that samples were obtained, and arrows signify a S0 application within the sampling period for each group of vines. No residue was detected on samples from the control treatment (no S0 applied, data not shown).
    Figure 3

    S0 residues on Riesling grape clusters sampled throughout the 2011 growing season. Sequential sprays of commercial sulfur formulations were applied starting 81 days before harvest and continuing at ~2-week intervals, ceasing a variable number of days before harvest on designated vines as denoted on the x-axis. S0 residue data are grouped by sulfur treatment, with each bar representing the mean value for a five-cluster sample taken from each of six treatment sampling units (2/replicate plot). The legend denotes the number of days before harvest that samples were obtained, and arrows signify a S0 application within the sampling period for each group of vines. No residue was detected on samples from the control treatment (no S0 applied, data not shown).

  • S0 residues in unsettled Chardonnay (2010) and Riesling (2011) juice after pressing as a function of residues measured on grapes at harvest. Each data point represents the mean value for six replicate measures of grape residues and three replicate measure of residues in the expressed juice, per treatment.
    Figure 4

    S0 residues in unsettled Chardonnay (2010) and Riesling (2011) juice after pressing as a function of residues measured on grapes at harvest. Each data point represents the mean value for six replicate measures of grape residues and three replicate measure of residues in the expressed juice, per treatment.

  • Hydrogen sulfide production during fermentation as a function of S0 residues in the initial, settled Chardonnay (2010) and Riesling (2011) musts. In 2010, fermentation replicates were racked for the same period of time but turbidity was not measured and residue concentrations differed among fermentation replicates; data points represent values for individual replicates. In 2011, all samples were settled to a turbidity of &gt;20 NTU and fermentation replicates were divided after racking; data points represent averages for three fermentation replicates per treatment.
    Figure 5

    Hydrogen sulfide production during fermentation as a function of S0 residues in the initial, settled Chardonnay (2010) and Riesling (2011) musts. In 2010, fermentation replicates were racked for the same period of time but turbidity was not measured and residue concentrations differed among fermentation replicates; data points represent values for individual replicates. In 2011, all samples were settled to a turbidity of >20 NTU and fermentation replicates were divided after racking; data points represent averages for three fermentation replicates per treatment.

  • Elemental sulfur (S0) residue present in juice pressed from fruit that received sequential applications of two commercial formulations (4.48 kg/ha S0) during 2011, ceasing either 54 or 12 days preharvest. Samples were obtained from 30 cm below the juice surface in a 20-L carboy, at the postpressing time intervals indicated. Data points represent the means for three replicate fermentations per treatment, with error bars indicating standard deviation. All means for 38- and 25-day PHI treatments were intermediate between those for the 12- and 54-day extremes but are omitted from the graph for clarity.
    Figure 6

    Elemental sulfur (S0) residue present in juice pressed from fruit that received sequential applications of two commercial formulations (4.48 kg/ha S0) during 2011, ceasing either 54 or 12 days preharvest. Samples were obtained from 30 cm below the juice surface in a 20-L carboy, at the postpressing time intervals indicated. Data points represent the means for three replicate fermentations per treatment, with error bars indicating standard deviation. All means for 38- and 25-day PHI treatments were intermediate between those for the 12- and 54-day extremes but are omitted from the graph for clarity.

Tables

  • Table 1

    Accumulation of heat units and precipitation during the periods between sulfur applications in field experiments, 2009 to 2011.

    Table 1
  • Table 2

    Transfer of S0 from Cabernet franc clusters into must and subsequent evolution of H2S during fermentation, as affected by vinification method.

    Table 2

Additional Files

  • Supplemental Data

    Supplemental Table 1
    Sulfur residue concentrations on Chardonnay grape clusters taken in 2009.

    Supplemental Table 2
    Sulfur residue levels on Chardonnay grape clusters taken in 2010.

    Supplemental Table 3
    Sulfur residue concentrations on Riesling grape clusters taken in 2011.

    Files in this Data Supplement:
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Persistence of Elemental Sulfur Spray Residue on Grapes during Ripening and Vinification
Misha T. Kwasniewski, Gavin L. Sacks, Wayne F. Wilcox
Am J Enol Vitic.  2014  65: 453-462  ; DOI: 10.5344/ajev.2014.14027
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