You've heard the hackneyed phrase "as American as apple pie." But America is not taking care of the apples -- or the orchard-keepers -- that have nourished us for centuries. In 1900, 20 million apple trees were growing in the U.S.; now, not even a fourth remain in our orchards and gardens. Today, much of the apple juice consumed in the U.S. is produced overseas. Of the apples still grown in America, just one variety -- Red Delicious -- comprises 41 percent of the country's entire crop, and 11 varieties account for 90 percent of all apples sold in stores.
When Joe Twine of Richmond, Ky., was growing up, "It was a must to have an orchard.
had orchards...he had apples come in at all times of the year," he recalls. "You don't see 'em anymore."
Of the 15,000 to 16,000 apple varieties that have been named, grown, and eaten in North American, less than 3,500 remain commercially available. Of the surviving varieties, nine out of ten are currently at risk of falling out of cultivation, and falling off our tables.
The drivers of these declines in apple production and diversity are many. There is no single man-made or natural cause. Changing land uses, tastes, and market pressures (far fewer varieties can be found in grocery and big-box stores, which value shipping resilience and item consistency, than in America's 5,000 farmers markets) have all had their impacts, but even they do not fully explain the long-term decline in the number of orchard-keepers and apple varieties out in the landscape.
Recent studies have suggested that orchard keepers face a new challenge to supplying a variety of apples to their customers. Shifts in weather patterns may be reducing the number of winter chill hours that apple and other trees require in order to bear abundant fruit. If trends continue as predicted, most California orchards are expected to receive less than 500 chill hours per winter by the end of the 21st century. Most apple varieties require 1,000 chill hours per winter to yield harvests large enough to keep orchards economically viable, although some require as little as 800 hours and a few can get by on just 500 chill hours.
EDIT
http://www.grist.org/article/whats-driving-our-favorite-fruit-into-decline/