Blighted tree at Springbrook Farm
A blighted tree at Springbrook Farm

 “Sorry about the dirt,” says Shawn Mehlenbacher, reaching out an earth-stained hand to greet recent visitors to Oregon State University’s Smith Horticultural Research Farm—his unofficial office—just outside of Corvallis. Calloused, cracked, and dirty, his hands are those of a laborer, not a lecturer. “I really can’t get it off,” he continues. “At harvest time, I just give up.” 

Mehlenbacher wears Levis and a well-kept work coat, and speaks with the measured diction of a scientist. Even normal conversation is peppered with plant-speak. His directions to the research farm, for example, are rooted in horticulture: “left before the hop yard ... left before the big trees ... park on the grass.” 

It’s understandable, for the trim, watchful man with mirthful eyes and a gray mustache has spent the better part of his five decades with his hands in the earth. Raised south of Rochester, New York, on a farm that grew oats, wheat, potatoes, and a handful of seed crops, Mehlenbacher learned early the hard labor—and hardship—that goes into farming. “I’m one of five children,” he says as he stops at the edge of a test orchard. “Every day after school, we were out there working until 6, and all day Saturday ... and in the summer it was pretty much 10 hours a day.” The farm’s gone now, but while collecting nuts during harvest Mehlenbacher still sits on his grandfather’s hand-built stool, a battered green and orange seat he shows off with pride. 

Once in college, Mehlenbacher’s love of science and biology blossomed. After earning his PhD from Cornell in 1982, he took up an assistant professorship in fruit tree breeding at Rutgers in New Jersey and landed at OSU in 1986 with his wife and young family. There, among the Smith Horticultural Research Farm’s rambling, shaded 160 acres, he anticipated a career in plant breeding and academia. 

But the researcher arrived to take over for Maxine Thompson, the founding plant breeder at OSU, just one month before the chilling discovery of blight in Oregon, and found himself suddenly in the middle of a war. Pruning and sprays offered temporary, sporadic, and expensive relief from the blight, but entire orchards were dying. Even strong fungicides like Bravo (for which the EPA granted a series of emergency provisions to allow) had little effect. As the disease spread inexorably south into the heart of the valley, some farmers chainsawed out acres of plantings—gouging huge holes in their orchards and their bottom lines. 

 “US Hazelnut Crop May Be Destroyed,” intoned an AP headline in 1988. Between the 1980s and the early ’00s, some 5,000 acres were lost—each worth at least $2,700 in annual production. Not even the Columbus Day storm of 1962 with its 130-mph winds had done this much damage. 

“It was spreading two miles a year,” Mehlenbacher recalls, “and we knew that 100 percent of the orchards were susceptible.” 

The only long-term solution lay in finding a blight-resistant species, which could take a generation (for hazelnut trees, about 17 years). Trouble was, the only promising species identified by Thompson and her colleagues—called Gasaway—bore small nuts and, worse, had very low nut yields. 

So Mehlenbacher did what any farm kid would: he rolled up his sleeves and applied his hard-earned work ethic to saving the hazelnut. Working out of the USDA Clonal Germplasm Repository in Corvallis—a kind of national gene bank for plants—Mehlenbacher and his OSU team set out to expand Thompson’s program by importing additional hazelnut cultivars from Europe, meticulously crossbreeding varietals, and planting between 4,000 and 5,000 seedlings each year. The goal: crossbreed a species hardy enough to resist the blight, but with kernels big enough to satisfy the ever-hungrier world market. 

When the blight showed up in OSU’s very own research orchards—a neighboring commercial farm had become infected—Mehlenbacher went into triage mode, juggling endless hours in the germplasm laboratory. Weekends and holidays ceased to exist. He logged tens of thousands of air miles on planes to foreign orchards—Azerbaijan, Russia, Georgia, Turkey—to stock and tag still more genetic samples. Iran brought him to a major agriculture conference in 2003; the Turks sought his counsel, too. (Turkey has the most to lose, with a $1.5 billion annual crop.)  

The fruits of Mehlenbacher’s labors still line the research farm’s office walls: hundreds of small Ziploc containers, each neatly labeled with a number (the tree’s location by row and tree number), holding a few handfuls of hazelnuts. And those represent only a fraction of the trees planted each year. On average less than 1 percent of every year’s seedlings—a collection of as many as 23 different crossbred varietals—make it to the next year. They are cut out as soon as they demonstrate susceptibility to blight or any number of other weaknesses. 

By 2009, despite the release of several improved tree crosses, EFB was still wreaking havoc, but a little hybrid dubbed Jefferson gave Mehlenbacher reason to hope.  


Shawn Mehlenbacher
Shawn Mehlenbacher shows off hazelnuts on one of his OSU research orchard trees.

Halfway down an unremarkable orchard row on the research farm, Mehlenbacher stops and turns, beaming. “This is Jefferson,” he says proudly. Pretty and plump, its boughs neatly pruned into a green and brown coif of leaves and limbs, it looks pretty much like every other tree in the row. But the hardy little tree—the descendent of an international mix from Sicily, Spain, Turkey, and the Northwest—has proven highly resistant to blight. Even better, it also resists mites and produces a good-size kernel. 

Mehlenbacher first planted the Jefferson cross, then known as OSU 703.007, in 1993. But the meticulous process of crossbreeding seedlings that grow into trees with a handful of promising traits—and a crop of nuts—takes a full generation. By 2009, Mehlenbacher was fairly sure Jefferson was a viable answer: Despite multiple inoculations with blight spores over its lifetime, Jefferson rarely contracted the disease. Even then, the scientist harbored some doubt. 

“I don’t think that plant breeders are ever 100 percent sure they have a winner,” says Mehlenbacher, noting even when it seems a cross will resist blight, the blight itself may be morphing to survive. “We release the best we have and let the industry decide what to plant.” 

In 2009, he sent Jefferson to market. It took. At the 2009 hazelnut growers society meeting, Mehlenbacher got a standing ovation. Speaking to a reporter from the Capital Press website at the time, Rich Birkemeier, a farmer, called him “genius.” An Oregonian article hailed him for having “saved the industry.” A quarter century after he had arrived among the tumult of an industry on the edge of extinction, Mehlenbacher had finally unraveled the mystery.

And yet, the war is not yet won. Mehlenbacher frets that Jefferson matures late in the season, upping the risk of a messy, rain-plagued harvest. (Hazelnuts simply fall to earth when ripe.) Replacing diseased or disease-prone orchards with the Jefferson varietal is expensive—roughly $2,400 per acre. Plus hazelnut trees take three to four years to produce nuts and don’t hit full production for another four to six years. That means even if farmers replace their diseased trees with new ones, they still must weather years of nonproduction—and no income. 

“Any way you transition is going to cost money,” says Polly Owen, manager of Oregon’s Hazelnut Marketing Board. 

For farms already hurting as a result of the blight, spending more isn’t an option. They are merely marking time until the end.