Remarkable stained skins arose in persimmon ‘Hiratanenashi’ fruits after treatment for the removal of astringency via 95% ethanol at under room temperatures (RA95%ETOH) in 2004. When the surfaces were observed at high magnification before RA95%ETOH, barely detectable fine cracks were invisible to the naked eye. Further, however, a multitude of cracks stained with methylene blue were found. We presumed the cause to be salty wind damage because many typhoons had passed through the Japan Sea and our country during the late summer season and the dirty flecks after RA95%ETOH had been distributed on the unilateral fruit surfaces. Subsequently, in 2005 and 2006, certain tests were carried out to assess whether spraying salt solution might reproduce the fine cracks, and whether certain washing treatments could inhibit the damage. In addition, two different treatments designed to remove astringency were tested to prevent staining of the skin. The proportion of the cracked area relative to the fruit surface after the spraying of 5% salt solution without washing was well approximated to that found in 2004. The proportion of one in 2004 and that in several treatments with 5% or 3% salt solutions, meanwhile, were significantly higher than the lower salt levels or 0%, while the stained skin after RA95%ETOH was very similar to that found in 2004. Stained skins after the removal of astringency at a temperature of around 20°C by 35% ethanol or that by carbon dioxide gas was very little. We hypothesized an explanation that the fruits might not have been moistened with water drops during the latter two treatments because of the constant air temperature. As countermeasures to prevent damage and stained skins, the following were proposed: washing with copious water immediately after the passage of a typhoon, removal of remaining water droplets from plant surfaces by the vibration of branches and selection of the astringency removal method.
