VATUKALO, Fiji — Before kava makes its way to a new wave of trendy bars in places like Brooklyn and Berkeley, Calif., it must be nurtured and plucked by people like Livai Tavesivesi.

A sun-weathered farmer on the Fijian island of Ovalau, Mr. Tavesivesi, 47, once farmed kava — the main ingredient in a drink long used by residents to attain a mellow buzz — much the way people here did for centuries. First, he washed its gnarled roots in a nearby river. Then he diced them, dried them in the sun and pounded them into powder with a tabili, a supersize mortar and pestle. Finally, he carried it three miles into town to be sold. “If we didn’t have a horse or car, we had to carry it,” he said.

Those traditional ways have led to bigger problems. Last year, Cyclone Winston devastated the island’s crop, threatening farmers’ livelihoods even as it sent kava prices soaring. More broadly, Fiji’s kava harvests have been inconsistent for years because of outdated techniques; the casual attitude of small-time farming has led to poor-quality products that do not pack the same pop.