The days grow cooler and the foliage begins to turn, signaling the advent of fall. But for allergy sufferers, the new season brings a host of miseries. The primary irritant for fall allergy sufferers is ragweed. This year’s unusually warm, dry, late summer has produced a bumper crop of pollen-producing weeds over the Plains, Midwest and Northeast. Composting leaves provide the perfect growth medium for molds, which also surge in autumn. For allergy sufferers, that means itchy, burning red eyes, scratchy throats, sneezing, wheezing, coughing and sinus congestion.