Salem, Ore.

TINY emerald cones on 18-foot-tall hops plants trembled as workers whipped the freshly cut stalks into roaring machines here at Sodbuster Farms. Gnashing metal fingers then stripped off the sticky cones  female flowers of the Humulus lupulus  and poured them onto conveyor belts, setting afloat bits of hops, like ash from a fire.

The debris, flecked with a resinous, yellow powder called lupulin, stuck in workers’ hair and eyelashes. Even more persistent was the aroma: a lemony, leafy, earthy scent that is precisely what brewers try to harness when brewing fresh-hop beers in autumn.

Hops give beer its distinctive bitterness and lend it other lively notes that range from citrus to flowers. But brewers usually use dried processed pellets of hops. The fall hops harvest is their brief window of opportunity to brew with the fresh green cones to make beers with a subtle range of hops flavor.

“You really get to taste the whole hop,” said Alan Jestice, an owner of the Blind Tiger Ale House in Greenwich Village, which serves fresh-hop beer on draft from Sierra Nevada and Two Brothers Brewing Company in Illinois. He said he enjoys their bright, herbal quality.