Diane Flynt plucks a Dymock Red from a tree, digs into it with her penknife, then hands me a wedge. The apple, a few weeks short of fully ripe on a warm, sunny early August morning, makes my mouth pucker — not with the unripe sourness of malic acid but with a searing astringency, as if the fruit has sucked my palate dry. It tastes nothing like a typical farmers market apple.