New hazelnut tree cultivars put brakes on rapid spread of Eastern filbert blight
By MATEUSZ PERKOWSKI
Once thought to be a death knell for the West's hazelnut industry, Eastern filbert blight is on the run, thanks to the efforts of an Oregon State University plant breeder.
During his 24-year tenure, plant breeder Shawn Mehlenbacher has released a dozen hazelnut cultivars resistant to the devastating fungal pathogen.
"If you were to ask the hazelnut industry what is the single most important factor in getting us through the Eastern filbert blight crisis, they would say the knowledge and work of Shawn Mehlenbacher," said Polly Owen, manager of the Hazelnut Marketing Board.
The fungus doesn't harm hazelnut species native to the Northeastern U.S., but kills the European varieties grown commercially for nuts.
Like the fungus, Mehlenbacher originated on the other side of the continent. Having grown up on a family farm in Castile, N.Y., Mehlenbacher was intrigued by plants -- but not by farming.
"Too much work for too little pay," he said.
Instead, Mehlenbacher pursued studies in horticulture and plant breeding. In 1982, he obtained a doctorate from Cornell University and soon joined the faculty at Rutgers University in New Jersey as a breeder of peaches, apples and apricots.
Mehlenbacher didn't know anything about hazelnuts when he landed a job at OSU four years later.
That wasn't a problem, though.
"If you're trained as a plant breeder, you can work on any crop," Mehlenbacher said, noting that he preferred to stick with specialty crops. Major commodities command a lot of attention from breeders, but with less prevalent crops, a single researcher can make a big impact, he said.
"It can be kind of lonely, but it's a tremendous opportunity," Mehlenbacher said.
By the time Mehlenbacher showed up at OSU, Eastern filbert blight was becoming a major problem in Oregon's Willamette Valley, the largest hazelnut-producing region in the U.S.
The pathogen is thought to have had been introduced to a hazelnut orchard near Vancouver, Wash., in the early 1960s. It festered for about a decade before it was discovered.
As the blight spread south through the Willamette Valley, farmers tried to slow its onslaught with a regimen of pruning and fungicide sprays.
It seemed like a losing battle. Such treatments are expensive and cannot permanently defeat the fungus.
Fortunately, Mehlenbacher was armed with an effective genetic defense. His predecessors at OSU had identified a cultivar, Gasaway, that was impervious to the fungus.
Unfortunately, the variety produced small nuts and low yields.
"Everything you want, Gasaway didn't have it -- except for Eastern filbert blight resistance," Mehlenbacher said.
The cultivar had to be cross-bred with higher-yielding varieties that produced bigger nuts.
The process was time-consuming. Mehlenbacher makes about 40 to 50 crosses annually, growing about 100 trees per cross. That translates to about 4,000 to 5,000 seedlings a year, each of which Mehlenbacher evaluates.
That number quickly shrinks as the trees begin to develop nuts. Most of them don't pass muster due to defects, slow maturity or susceptibility to parasites.
"You have to have a pretty good idea of what you're looking for, what's acceptable and what's not acceptable," he said.
Since coming to OSU, Mehlenbacher has produced more than 100,000 seedlings. Only 12 varieties have been released for commercial production, but they've earned him tremendous gratitude.
"It takes a lot of patience," said Wayne Chambers, a hazelnut grower who has cooperated with Mehlenbacher on field trials. "It takes insight to make the right crosses."
Rich Birkemeier, another farmer who works with Mehlenbacher, said he's in awe of the breeder.
"I find the man to be amazingly prophetic in the decisions he makes," Birkemeier said. "I would classify him in the genius category when it comes to understanding that science and being able to apply it in the field."
Mehlenbacher is still not content. In recent years, he has traveled the world looking for new sources of genetic resistance to the blight. His searches have turned up about a dozen resistant varieties, four of which have been confirmed to provide a different type of resistance.
Mehlenbacher is excited about several crosses still in the experimental phase, which he expects will eventually outshine released varieties.
"I think the crowning achievement is yet to come," he said.
Occupation: Oregon State University plant breeder
Hometown: Castile, N.Y.
Family: Wife, Stephanie, and two grown children
Education: Bachelor of science in Horticulture, Pennsylvania State University, 1978; doctorate in Plant Breeding, Cornell University, 1982