Summary: This year we have expanded our investigation of the effects of 4-methyl cyclopropene (MCP) on apple fruit ripening in general and scald in particular. We used "Granny Smith" and "Red Delicious" apples, both of which are scald-susceptible. We measured the following parameters: ethylene (C2H4) evolution, levels of a-farnesene and conjugated trienol, and texture. We also compared the effects ofMCP on scald to those of 1.5% oxygen (02) on scald.