Commercial orchards of loquat in Israel are planted in 350 hectares, at densities of 500-750 trees per ha, mainly in the coastal plain. Many orchards are covered with a continuous overhead net. In sensitive cultivars (i.e. Akko-1, Zikim, Tannaka, Emmanuel), incidences of physiological disorders (russet and purple spots) occurred in as much as 50 percent of the fruit in certain years. The extent of the damage varies between years and cultivars and it seems to be influenced by microclimatic conditions. In order to develop means for alleviating the damage studies were made to identify some of the causes contributing to the phenomenon.