Varieties such as Jonathan , Stayman and Winesap retain their fruit until it is overmature. In addition, seasonal conditions and culture affect the tenacity with which fruit stems cling to the spurs. Ethrel advances fruit ripening and stop-drop chemicals prevent fruit drop. Firmness of fruit Flesh becomes softer as an apple matures on the tree. This process should be repeated 10 to 20 times with apples picked randomly.
Commercial harvests vary depending on the variety.
Red Delicious apples should be harvested at 15 to 18 pounds of pressure for optimum storage. Golden Delicious apples should be harvested at 14 to 17 lbs. If long-term storage is anticipated, fruit should be harvested in the higher firmness range. This index, even when used independently, is of value in determining when apples are too soft or ripe for storage. It is important to remember that firmness varies from season to season and factors other than maturity can affect firmness.