Host involvement in the improved decay control following NaHCO3 co-application with imazalil

In order to improve the treatment efficiency of conventional synthetic fungicides we investigated the relationship between the decay control efficacy and the concentration of imazalil (IMZ) when the fungicide was co-applied with NaHCO3 (SBC) for 2 min. Experiments were carried out using lemon fruit (Citrus limon (L.) Burm .f. cv Verna), either wounded or not before the treatment with 0, 50, 100, 250 or 1000 microg mL(-1) IMZ or the co-application of 3% SBC with 0, 50, 100 and 250 microg mL(-1) IMZ. Wounded lemons were used to simulate and study, the host-fungicide interaction in a potential infection court as affected by the SBC-IMZ coapplication. The occurrence of natural decay was monitored after 7, 14 and 30 days of storage at 8 degrees C and after a 6 day simulated marketing period (SMP) at 20 degrees C and 75% RH. During storage and SMP a comparable efficacy to 1000 microg mL(-1) IMZ, in controlling natural decay development, was obtained with a ten times lesser amount of IMZ when co-applied with SBC. Studies performed following the SBC-IMZ co-application evidenced the induction of natural resistance along with structural changes and an increase of IMZ allocated in the potential infection courts.