‘Italia’ grape is one of the most important table grape cultivars grown worldwide. Gray mold, caused by Botrytis cinerea Pers. Fr., is one of the most important causes of postharvest decay of table grapes, and the control of this disease is very difficult because postharvest treatments with synthetic fungicides are not allowed in many countries. The objective of this study was to compare different types of pads releasing different doses of SO₂ during cold storage to control gray mold in ‘Italia’ table grapes grown under subtropical conditions. Grape bunches were harvested from a commercial field trained on an overhead trellis located at Cambira, state of Parana (PR), South Brazil. The grapes were packed into carton boxes (capacity, 4.5 kg) and subjected to the following SO₂ pad treatments (Uvasys^®, Cape Town, South Africa) under cold storage (1.0 ± 1 °C) for 50 days: (i) Control; (ii) SO₂ slow release pad; (iii) SO₂ dual release pad; (iv) SO₂ dual release–fast reduced pad; (v) SO₂ slow release pad with grapes inoculated with B. cinerea suspension; (vi) SO₂ dual release pad with grapes inoculated with B. cinerea suspension; and (vii) SO₂ dual release-fast reduced pad with grapes inoculated with B. cinerea suspension. After cold storage, the grape boxes were maintained for 7 days at room temperature (25 °C). The incidence of gray mold on the grapes, firmness, shattered berries, stem browning, as well as other physicochemical variables, such as bunch mass, bunch mass loss, skin color, soluble solids (SS), titratable acidity (TA) and SS/TA were evaluated. Both SO₂ dual release pads were highly efficient in preventing the incidence of gray mold in ‘Italia’ grapes packed in clamshells during the 50-day period of cold storage and at room temperature, even with Botrytis-inoculated berries. The SO₂ slow release pad showed lower efficiency, but was higher than the control. The SO₂ dual release pad treatments provided the best results with respect to stem browning scores (fresh and green stems) during cold storage, and no differences were observed among the treatments with respect to the other physicochemical evaluations.

The use of vented clamshells has become popular in the packaging of grapes for local and international markets. The aim of this study is to evaluate the postharvest preservation of ‘Benitaka’ table grapes individually packaged in vented clamshells using different types of SO₂-generating pads and perforated plastic liners during cold storage. A completely randomized design with four replications in a two-factor arrangement with an additional treatment [(4 × 3) + 1] was used. The trials were carried out under two situations: Artificial or natural infections with Botrytis cinerea, which is the causal agent of gray mold on table grapes. The incidence of gray mold, shattered berries, and stem browning were evaluated at 30 and 45 days of cold storage at 1 ± 1 °C and 3 days of shelf-life at 22 ± 1 °C after the period of cold storage. Mass loss and berry firmness were also examined at the end of the cold storage period. The use of dual-release SO₂-generating pads containing 5 or 8 g of a.i. and slow-release pads with 7 g of a.i. was effective in controlling the incidence of gray mold in grapes packaged in vented clamshells and kept under cold storage for up to 45 days. Under these storage conditions, perforated plastic liners with 0.3% ventilation area or micro-perforated liners with 1.0% ventilation area reduced the percentage of mass loss and shattered berries.

The purpose of this research is to test the efficacy of different types of SO₂-generating pads on the incidence of gray mold, and on the physicochemical properties of quality of ‘BRS Nubia’ seeded table grapes grown under protected cultivation. Four types of SO₂-generating pads, 5 or 8 g of sodium metabisulfite dual release pads, and 4 or 7 g of sodium metabisulfite slow release pads, were used. Grapes bunches were harvested from a vineyard covered with plastic mash and stored in a cold room at 1 ± 1 °C for 45 days followed by 6 days of shelf life at 22 ± 1 °C at a high relative humidity (>95%). The results showed that SO₂-generating pads with a dual release of 5 or 8 g completely inhibited the development of gray mold at all evaluation times. Also, a high reduction of the disease incidence was achieved by using a slow release of 4 g. The study confirmed that SO₂-generating pads did not alter the physicochemical properties of ‘BRS Nubia’ seeded table grapes including mass loss, berry firmness, color index, total anthocyanin concentration, total soluble solids (TSS), titratable acidity (TA), and the TSS/TA ratio. Slow release pads at 4 and 7 g reduced the percentage of shattered berries by 56 and 48% as compared to control only after 6 days of shelf life. Also, all types of SO₂-generating pads reduced the stem browning score at the end of cold storage. The 5 or 8 g dual release pads and 4 g slow release pads can be considered for effective controlling of gray mold for ‘BRS Nubia’ table grapes grown under protected cultivation while maintaining grape quality.

‘BRS Vitoria’ (Vitis spp.) is a novel hybrid seedless table grape recommended for cultivation in tropical and subtropical areas, especially for overseas export. The main postharvest disease of this cultivar is botrytis or gray mold (Botrytis cinerea), which occurs even under low temperatures in cold chambers. Sulfur dioxide (SO₂) release pads have been used to control this disease under cold storage, but some grape cultivars are sensitive to certain levels of this compound. The objective of this work was to evaluate different types of SO₂ generator pads in order to prevent the incidence of gray mold of ‘BRS Vitoria’ seedless grape, as well to avoid other grape injuries during cold storage. Grape bunches were harvested when fully ripened (16°Brix) from a commercial field trained on overhead trellis and located at Marialva, state of Parana (PR) (South Brazil). Grapes were packed into carton boxes and subjected to the following SO₂ pad treatments (Uvasys^®, Cape Town, South Africa) in a cold chamber (2 °C): (a) control; (b) SO₂ slow release pad; (c) SO₂ dual release pad; (d) SO₂ dual release–fast reduced pad; (e) SO₂ slow release pad with grapes inoculated with B. cinerea; (f) SO₂ dual release pad with grapes inoculated with B. cinerea; and (g) SO₂ dual release–fast reduced pad with grapes inoculated with B. cinerea. After a 50-day cold chamber period, the grape boxes were kept for 7 days at room temperature at 25 °C. A randomized design was used with seven treatments and four replications, with five bunches per plot. The incidence of gray mold on grapes was evaluated after the 50-day cold storage and after the 7-days-at-room-temperature periods, as well other grape physicochemical variables, such as shattered berries, stem browning, bunch mass, bunch mass loss, skin color, soluble solids (SS), titratable acidity (TA), and SS/TA. The dual release pads were more efficient in preventing the incidence of gray mold and mass loss in ‘BRS Vitoria’ seedless grapes than the slow release pads in both storage periods. The incidence of shattered berries was lower when any type SO₂ pad was used during cold storage, and no effects were observed on stem browning, firmness, or berry skin color of ‘BRS Vitoria’ grapes.

‘BRS Isis’ is a new hybrid seedless table grape tolerant to downy mildew with a good adaptation to the tropical and subtropical climates. Gray mold, caused by Botrytis cinerea Pers. ex Fr. is known as the most important postharvest mold in table grapes, causing extensive losses worldwide. As the postharvest behavior of ‘BRS Isis’ is still unknown, the objective of this work was to evaluate the postharvest preservation and B. cinerea mold control of this new grape cultivar, grown under the double-cropping a year system. Grape bunches were purchased from a field of ‘BRS Isis’ seedless table grapes trained on overhead trellises located at Marialva, state of Parana (South Brazil). Grapes were subjected to the following treatments in a cold room at 1 ± 1 °C: (i) Control; (ii) SO₂-generating pad; (iii) control with bunches inoculated with the pathogen suspension; (iv) SO₂-generating pad with bunches inoculated with the pathogen suspension. The completely randomized experimental design was used with four treatments, each including five replicates. The incidence of gray mold and other physicochemical variables, including bunch mass loss, shattered berries, skin color index, soluble solids (SS), titratable acidity (TA), and SS/TA ratio of grapes, were evaluated at 50 days after the beginning of cold storage and at seven days at room temperature (22 ± 2 °C). The ‘BRS Isis’ seedless grape, packaged with SO₂-generating pads and plastic liners, has a high potential to be preserved for long periods under cold storage, at least for 50 days, keeping very low natural incidence of gray mold, mass loss, and shattered berries.

SO2-generating pads reduce gray mold in clamshell-packaged ‘Rubi’ table grapes grown under a two-cropping per year system