Search

The influence of the immersion of lemon fruit in aqueous imazalil (IMZ) mixtures at 25 or 50 °C on the deposition and persistence of IMZ within the fruit rind and its effectiveness in controlling postharvest green mold, caused by Penicillium digitatum, was investigated. Concentrations of IMZ in the albedo tissue surrounding deep wounds in the rind were higher than the mean EC50 values for IMZ-resistant strains (1.0 ?g ·mL-1) after immersion of fruit into IMZ mixtures containing 25, 50, or 75 mg· L-1 heated to 50 °C, but not those at 25 °C, where fungicide deposition was insufficient. IMZ residue, one day after treatment with 25, 50, or 75 mg· L-1, was 3, 5, or 7 times higher after treatment at 50 °C compared to treatment at 25 °C. IMZ residues within the albedo of unwounded fruit treated with 25, 50, or 75 mg· L-1 at 50 °C were 0.8, 1.3, or 2.0 ?g · g-1, respectively, while those similarly treated at 25 °C had negligible residues. Residues following treatment at 50 °C in the albedo did not decline during storage at 10 °C after 60 days. IMZ residues in the flavedo were higher than those in the albedo: after treatment with 25, 50, or 75 mg· L-1 IMZ, they averaged 1.0, 1.2, or 2.7 ?g · g-1, respectively, after treatment at 25 °C, and 5.5, 7.9, or 16.2 ?g · g-1, respectively, after treatment at 50 °C. IMZ effectiveness as an eradicant to control green mold improved when it was heated. Green mold was reduced by 22 or 95% after treatment of lemons inoculated 1 h before immersion of lemons in IMZ at 50 mg· L-1 at 25 or 50 °C, respectively. Green mold was reduced by 18 or 61% after treatment of lemons inoculated 1 day after immersion of lemons in IMZ at 50 mg· L-1 at 25 or 50 °C, respectively. Scanning electron microscopy of the rind surface indicated that treatment at 50 °C for 2 min also caused ruptures in the cuticle.

A method for the inclusion of imazalil (IMZ) in the ‚Beta-cyclodextrin (Beta‚CD), structural characterization of the inclusion complex and its antifungal activity against Penicillium digitatumand P. italicumassessed by in vitro and in vivo tests are reported. According to the starting stoichiometry of BetaCD with respect to IMZ, an equimolar ratio ‚Beta-cyclodextrin-IMZ (BetaCD-IMZ) was detected by 1H NMR. In vitro assays showed that the freshly prepared BetaCD-IMZ was as effective as IMZ, although 1- and 4-day-old BetaCD-IMZ mixtures were more effective. Studies on Star Ruby grapefruit showed no significant differences in residue uptake between treatments with an IMZ commercially available fungicide (Deccozil) or BetaCD-IMZ when equal active ingredient (a.i.) concentrations (250 mg/L) and dip temperatures (20 or 50 °C) were used. By contrast, treatments of Tarocco oranges and Di Massa lemons with 250 mg/L BetaCD-IMZ at 50 °C produced significant differences in residue uptake in comparison with 250 mg/L Deccozil treatments at 50 °C. The a.i. degradation rate in grapefruit during postquarantine and simulated marketing period (SMP) at 20 °C was not affected by the type of formulation used, whether at 20 or 50 °C. Conversely, IMZ in oranges and lemons had greater persistence when applied at 50 °C. All fungicide treatments showed a comparable efficacy against decay in grapefruit and oranges, whereas treatment in lemons at 250 mg/L a.i. of heated fungicides had higher suppressive effects against decay than unheated chemicals having equal a.i. concentrations and comparable activity at 1200 mg/L IMZ at 20 °C.