STEAM HEAT TREATMENT AND FUMIGATION WITH ACETIC ACID TO CONTROL BOTRYTIS CINEREA IN KIWIFRUIT

The present study was undertaken to investigate the effect of steam treatments on growth of Botrytis cinerea after artificial inoculations on 'Hayward' kiwifruit: (1) at the stem end abscission zone, or (2) at the equator zone, after wounding the fruit. Steam treatments were applied at 45°C, 47.5°C, and 50°C for 15 min. At the stem end abscission zone, treatment at 45°C showed a high incidence of decay, while treatment at 47.5°C showed a significant reduction of fungal growth, and treatment at 50°C showed a complete inhibition of growth of the fungus. On the other hand, none of the treatments completely inhibited growth of B. cinerea in vivo when inoculations and wounds were made at the equator zone. A significant reduction of fungal growth was observed only in treatment at 50°C for 15 min. A further study was undertaken to investigate the effect of acetic acid fumigation, combined with modified atmosphere packaging (MAP), on the growth of B. cinerea after artificially inoculating 'Hayward' kiwifruit: (1) at the stem end abscission zone, or (2) at the equator zone after wounding the fruit. Acetic acid fumigations with 2.5, 5, and 10 mg/L for 3 min and 6 min resulted in no incidence of decay on the abscission zone of the stem end of the kiwifruit. However, none of the acetic acid treatments completely inhibited fungal development after wounding the fruit by inoculation at the equator. Treatments with 2.5 and 5 mg/L for 3 min and 6 min only reduced decay, while treatments with 4, 6 and 8 mg/L for 6 min significantly reduced but did not completely inhibit decay.