Controlling grey and blue mould diseases of apple fruits using acetic acid vapours

Abstract

The effect of acetic acid vapours at three application times on grey and blue moulds on the incidence of apple fruits was studied. Acetic acid vapour at 6 µl/l caused complete inhibition of linear growth and spore germination of Botrytis cinerea and Penicillium sp. The most effective concentration was AA at 4 µl/l, which reduced spore germination and linear growth by more than 82.4 and 68.3% of both fungi respectively compared with un-fumigated fungi. On other trials the diameter of the inhibited growth zone of both fungi gradually increased as AA concentrations increased. The highest increase in inhibition zone diameter was obtained with AA at 12 µl/l followed by AA at 8 µl/l, meanwhile AA at 4 µl/l had a moderate effect. Apple fruits were divided into three groups, the first was fumigated at 24 h before inoculation, the second at zero time the and third at 24 h after inoculation and storage for 30 days. Results indicate that the higher reduction of grey and blue mould incidence was obtained with AA at 12 µl/l of three application times which reduced the disease incidence by more than 81.0, 81.0 and 73.5% before, at zero time and after inoculation, respectively. Acetic acid at 8 µl/l reduced the incidence of both diseases more than 52.0% with all application times. As for application times the most effective times were 24 before and at the zero time of inoculation which reduced both diseases more than 81.0 and 75.5 with AA vapours at 12 and 8 µl/l, respectively. Meanwhile treated apple fruits after inoculation was less effective. The same trend between disease incidence and percentage of rotted tissue parts was observed. It could be suggested that acetic acid vapours might be safely used commercially for controlling post-harvest disease of apple fruits during storage.

Keywords:

• Acetic acid
• apple fruits
• fumigation
• blue mould
• grey mould