MOXEE, WASH. -- The scene is arresting, moving from the arid sagebrush desert east of the Cascades into the lush irrigated foothills, as Leslie Roy's intricate contraptions loom on the horizon.

Acres and acres of heavy fir poles rise 18 feet, criss-crossed on top by taut wires and linked to the ground by strands of hand-spun Indian coconut-fiber yarn (seven miles of it to the acre). Roy's crop twines around the strands and spirals upward toward the sun, forming golden buds that soon will go to market.

There is nothing comparable in American agriculture, in complexity or capital investment or hand-labor demands. This is a world center of hops production and Roy, with 750 acres covered with trellises, is one of the world's largest growers.

Roy is one of about 150 U.S. farmers who grow hops, a rough, twining vine whose flowers give beer flavor and aroma, preserve the brew and stabilize foam. Yakima Valley "Yaks" -- as they are known in the brewing trade -- account for roughly two-thirds of the 33,000-acre U.S. crop and are prized worldwide for their quality. Oregon and Idaho grow most of the rest of the crop.

A question arises. Given the heavy start-up costs (a custom-built harvesting machine goes for $750,000), why would farmers bother with hops when they could grow other crops with much more ease and possibly just as much profit?

Roy's answer -- that "it's unique" -- is another way of saying that he and his hop-growing colleagues take pride in knowing they are among the country's few producing a crop as important in its own way to satisfying the palate as exotic herbs or durum wheat.

"It's a way to make a living," Roy said. "It can be as profitable as any agricultural commodity if the market is right. But then, the returns really don't justify the investment . . . . It's very capital-intensive, very labor-intensive, so expensive that it's hard for someone to get into the business."

Which says it all. Roy, an agricultural economist, is the inheritor of a family farming tradition that goes back to the turn of the century when his grandfather came to the Yakima Valley from Quebec and began growing hops.

Roy's father, who oversees the family's vast operations here, carried on the hops tradition and expanded the plantings. Roy now is the major-domo of the hops, and three brothers tend to other aspects of the family's apple and cherry growing, marketing and management.

The Roy farm produces 11 varieties of hops, each of which has a different demand cycle and a different use in the brewing process. A large greenhouse is maintained for root propagation of new and hard-to-find varieties that the Roys speculate will be in demand.

"A lot of new varieties are coming on," Roy explained, "but it takes 10 years to develop a new one. We grow them because we want to stay ahead of the others . . . . For example, we're now trying to raise more aromatic hops -- we used to do only the bitters, and the Europeans raised the aromatics. Now they're doing more of the bitters."

New York was the top hops producer in the early 1900s, but the industry was drawn west by the appeal of dry climate (preventing mildew), long hot summer days and cool nights, and ample water for irrigation. The Yakima Valley's primacy as a growing zone has brought major dealers, processors and shippers here to handle each fall's crop.

Work on this year's crop began late last winter as field hands strung new twines, braced trellis poles and put in new plants. As the hop plants begin to grow, they must be trained by hand onto the twines, and since chemical companies have not developed a weed-killer suitable for hops, the crowded rows between the poles must be cultivated by hand.

When the harvest begins late this month, the Roys' picking machines will work around the clock until the crop is in -- probably at the end of September. The vines will be picked clean of the hop flowers, which will then be moved into drying rooms to reduce moisture content and sealed into 200-pound bales ready for the brewery.

Last year was one of the best in a long time for Washington hops growers, with an average price of $1.62 a pound for a crop that averaged 2,000 pounds an acre. A Washington State University study in 1985 found that a price of $1.52 was necessary to turn a profit.

Despite the better fortune last year, all is not well in the hops industry. Although beer production increases, the hopping rate has declined steadily for two decades as nationally marketed brands turn to more blandness and uniformity.

The pressures of subsidized competition from European Community growers and a large world surplus in recent years have pushed some U.S. growers out of the business in what Bill Harris of the Hop Growers of America calls "a terrible wringing-out process."

While its growers' tracts are much smaller than those here, West Germany continues to lead the world in hops production and commands a certain market share based simply on the German reputation for making quality brew.

"Our hops go all over the world, and we have some very good customers such as Mexico, Brazil, Colombia and Canada," said Harris, who is based in nearby Yakima. "But one thing that complicates it for us is that there's a German in the background no matter where you go in the world of brewing . . . a built-in bias toward hops, malt and many ingredients. We do well in countries where there is not that German influence.

"We feel our potential is greater for capturing markets because of the consistency and quality and varieties that we grow here," Harris said. "We're certain that production will be larger in the years ahead; we think markets will increase. And we hope many farmers who were pushed out will be back as the markets improve."

While mainline beers use only about a quarter of a pound of hops per 31-gallon barrel, the increasingly popular and distinctive boutique beers popping up across the United States are one of the hops industry's new hopes.

"We're very interested in the microbrewery movement," Harris said. "These beers that are identified as superpremium or specialty beers are distinctive because they have more ingredients."

Another element in the domestic picture is the potential effect of a growers' vote last year ending a federal marketing order that allocated market shares to farmers and, in effect, limited the entry of new growers. The order flashed to controversy in the early 1980s when the Reagan administration criticized it as antithetical to free-market agriculture.

Growers were so bitterly divided over the issue that few seem willing to talk about it today for fear of reviving old antagonisms. But, said Harris, "Most people are saying it's just too early to tell what effect the ending of the marketing order will have."