Is fruit firmness the best measure to determine when to harvest apple fruit?

Apple flesh firmness is one criteria that is used to determine the maturity, and quality, of apples.  However, it is not the best single  indicator to determine the harvest maturity for apples.  Apples are harvested at different stages of maturity depending on how long they will be in storage before marketing. Apples to be used shortly after harvest are tree ripened and picked at a much later stage of maturity than apples that will be stored for 6-9+ months.  Flesh …

Does an apple cultivar ripen at the same time every year?

Not necessarily. Time of apple ripening is affected most by bloom date and growing season weather. For example, McIntosh typically ripens 125 Days After Full Bloom (DAFB), but can range from 115 to 135 DAFB. There are formula(s) for determining harvest timing, for example, this one for McIntosh from Cornell University. In any year the best indicator of maturity and harvest timing is a combination of flavor and fruit background and over-color, but the starch-iodine index test is also …

How do I know when it is the right time to pick an apple cultivar?

Time of harvest depends on the intended use of the apples.  Apples that will be consumed immediately can be left on the tree longer than those intended for cold storage. Generally, fruit can be harvested from the tree over a couple of weeks. Fruit that drops from the tree is usually over ripe.  To determine the approximate time of harvest, check a fruit tree nursery catalog or their web site for a list of harvest dates for various cultivars. These …