Research continues as interest grows

Photos courtesy of Rutgers University.
Nut quality is the final leg of the hazelnut breeding program at Rutgers.

The hazelnut has never been a decent commercial crop in the northeastern United States. The native American hazelnut species has never had the nut quality, and the imported European species has severe disease and cold tolerance issues that have prevented it from catching on in this part of the country. There is a scientist at Rutgers University who is devoted to creating a viable hazelnut for this area.

Tom Molnar is an assistant professor and a plant breeder who has spent the last decade trying to find suitable plant materials, cross them and come up with one or more varieties for commercial growers. There is a surprising amount of interest in a nut that has not been a major food crop in the United States, including work being done at the USDA, Oregon State University, the University of Nebraska at Lincoln and private breeders, but Rutgers is focused on finding a plant that will overcome the considerable drawbacks for the tree in the Northeast.

Actually, the hazelnut in its usual configuration is more of a large monoecious shrub than a tree. The native plant, Corylus americana, normally tops out at 8 to 10 feet, while the European species, Corylus avellana, grows a little taller and is often cultivated as a single-trunk tree. The native nut is small and poor in quality. Although the European species was brought to this country in the 1700s, the major commercial planting has been in Oregon.

That West Coast crop has been threatened in recent years by the same disease that prevented growth of the European tree in the Northeast: the eastern filbert blight. This fungus is endemic in North American hazelnuts, but the native trees are resistant to it. Molnar says it is the biggest reason why a commercial crop hasn’t been established in either the Northeast or the Midwest. The Oregon industry recently was also hit with the disease, and also is trying to breed resistant variations.

The other major drawback to the Northeast is that the European hazelnut doesn’t have the cold hardiness that is required for consistent nut production. The plants will survive, and even thrive, but in many local environments the male flowers, or catkins, will emerge early in the spring during a warm spell, and then sustain frost damage when cold weather returns. Molnar notes that it usually takes a below-zero temperature to damage the plant, but during the spring a drop in temperature down to 20 degrees can ruin a nut crop.

“Some of the earliest colonists to the area brought hazelnuts,” says Molnar, who in his short tenure at Rutgers has become a leading expert on the topic. He notes that disease and cold issues have made the U.S. a minor producer. In 2007, worldwide production was 761,890 tonnes, with the U.S. producing only 32,660 tonnes of that, most in the Willamette Valley of Oregon.

Tom Molnar, left, John Capik, right. One of the most important trials for the hazelnut trees grown at Rutgers University is testing for eastern filbert blight.

Molnar and colleagues at Rutgers are trying to change that by changing the equation. He was originally headed for a turfgrass specialty, but changed course when another turfgrass researcher, C. Reed Funk, now retired, began investigating hazelnuts as an alternative food crop in the late 1990s. They began by collecting plant materials, both seedlings and nuts as seeds, from all the obvious sources such as USDA, university and private breeding projects and nurseries.

Molnar travelled to the other side of the world to collect hazelnut plant materials. He went to research stations in Russia, the Crimea and Poland, as well as to private growers and markets. In particular, he was looking for varieties that would not only produce a high-quality nut, but also would not flower until late March or early April.

“We now have over 20,000 trees out in the field in different locations that are under trial here,” Molnar says of the collected species and their crosses and progeny planted in and around New Jersey. About 10,000 of those trees are hazelnuts. They are looking particularly at second and third-generation hybrid crosses.

There has been an intensive attempt to cross native American hazelnuts, which are tolerant of eastern filbert blight, with the collected plant materials derived from European stock. Molnar says that blight resistance is the first consideration, and that sorts itself out pretty quickly. The fungus grows under the bark of the plant, but doesn’t manifest itself the first year. In the second or third year, the tree will die if it does not have resistance, which makes it easily eliminated from a trial.

Plants that survive these early cullings are later examined for cold hardiness and reliability of production. Factors such as the tendency for hazelnuts to be alternate bearing are looked at. There is also an analysis of nut size, kernel percentage and flavor as part of the ultimate selection process. In addition, advanced genetic techniques, such as the use of specific gene markers for identifying blight tolerance, has helped speed up the selection process. Some of these techniques, as well as good breeding stock, have come from an active breeding program at Oregon State University. OSU has developed and released excellent commercial hybrids, with blight resistance, for use in the West, but Molnar says those selections don’t have the cold hardiness necessary for success in the Northeast.

Plant breeding of trees is a long process. It takes about seven years to grow out a hazelnut plant and get an accurate determination of the above elements. They are then crossed with late-flowering plants, and that can take another six years to evaluate. To illustrate how rare the top crosses are, Molnar says that only two hazelnut cultivars derived from all of the Russian material remain as candidates. He says he has no “wonderful” plant isolated yet, but there are several candidates, and the university is pushing hard to find ones that have all the qualities necessary for commercial production.

“I hope that within five years we will have plants out for testing,” he says. Those will be small plots that will simulate on-farm cultivation in several different climatic and geographic areas. “We do have plants in the pipeline that look really promising.”

He doesn’t know how long it will be after that when commercial varieties will be available, but at least a good result is in sight for USDA Plant Hardiness Zones 6 and 7. In order to develop trees for even colder areas in Zone 5, there will have to be a further selection process. Molnar says that this year, Rutgers entered into a working agreement with the University of Nebraska at Lincoln and the Arbor Day Foundation to look at plants for the colder zones. He is using some of the Nebraska plant materials, and they are using some of his.

As far as areas where the initial release of hazelnut varieties could be a viable farming proposition, he says much of the Northeast and Midwest, as well as warmer parts of Canada, would be possibilities. Local microclimates would have to be analyzed, but he foresees that this could be a perennial crop that could be grown right down into the Mississippi Valley.

To illustrate the interest in hazelnuts, look at Ernie Grimo in Niagara-On-The-Lake, Ont., Canada. The owner of Grimo Nut Nursery, he sells 16 varieties of hazelnuts and has an orchard where he screens the stock he gets in from various sources. He has also made some selections himself, searching for trees with the same characteristics Molnar is looking for.

Grimo says that various attempts have been made in the past to grow hazelnuts in southern Ontario where Great Lakes water moderates the temperature, and only the remnants remain. There is a lot of interest in reinvigorating the crop, though, especially in the sand plains north of Lake Erie, where a candy factory hopes to utilize the nuts, and there is a lot of interest from potential growers.

(Left) Cold hardiness is important, because trees that flower early can suffer frost damage to the male catkins. (Right) Spring nut clusters of the European hazelnut.

“I believe that hazelnuts would do best close to the Lakes Erie, Ontario and in the fruit-growing area of Georgian Bay where tender fruit and grapes can be grown,” Grimo says. Some new trees with eastern filbert blight resistance have been planted, but it is too early to tell whether they will have the cold hardiness required. Many of the selections he sells as clones and seedlings are from his own experiments as well as the discoveries of previous researchers, and nut quality is high in some. He acknowledges that he is unsure how they will perform long-term. The University of Guelph is currently under-taking a trial of 15 cultivars, which will expand to 30 next year.

Phillip Rutter, CEO of Badgersett Research Corporation in Canton, Minn., has been growing and breeding hazelnuts for 30 years and has finally gotten the cold tolerance and blight tolerance set, saying that some of his trees can even grow in Zone 3. He also has gotten some hybrids that can grow a balanced annual crop, and is now looking at the next level, which is getting tasty ones.

(Above) This Ontario hazelnut tree, grown by Grimo Nut Nursery, is one of many being looked at for the Canadian situation. (Above right) The American hazelnut is being used to breed resistance to the eastern filbert blight, which is deadly to the European species within three years. (Right) Hazelnuts have been collected from as far away as Russia to use as crosses in the breeding program.

“The results of breeding indicate that this is really a doable thing,” Rutter says of the idea of hazelnuts as a commercial crop. He says there are about 50 growers in the upper Midwest using his varieties to grow a few acres, and about five of them will have a significant harvest this year. But, once sizeable acreage begins going in the ground, the next challenge will be to develop the mechanization to harvest the bushes and process the nuts.

Much of the interest in the Midwest, Rutter says, is in the nut as an oil crop as much as a food crop. Once corn farmers become disenchanted with the ethanol market, there could be even more interest in hazelnuts as an alternative.

From what Molnar has seen, he projects that in the short term, before eastern hazelnuts are grown in large acreages, they will be a part of the popular sustainable agriculture movement. They will likely be grown on small farms on either agricultural soils or in situations such as sloped land where other crops won’t grow. They are soil-adaptable as long as they have good drainage, and he is starting a list of prospective growers who will be the first to receive trees in the next three or four years. He cites as an example a Long Island, N.Y., man who will be planting some stock next year and wants to be in the vanguard of testing new plant materials and growing methods.

Molnar says that his test trees have not needed irrigation after the first two years. “They seem to be really drought-tolerant,” he says, acknowledging that New Jersey isn’t going to be the true test of that trait. He uses a general, balanced fertilizer to keep the test trees healthy enough to assess their capabilities.

“They do respond to nitrogen fertilizer. It’s really essential, as is weed control,” he says. He has done no pest control here and sees no major damage done by insects, though in other areas, such as Oregon, pests have arisen. The crop promises to be well-adapted to commercial agriculture in many forms, including organic. Once the other issues have been sorted out, the hazelnut will have to undergo the normal farm experimentation process to establish good yields.

Another element that will have to be sorted out is the marketing of the crop. Hazelnuts are an established food crop—much more so in Europe than in the U.S.—but only the Oregon hazelnut industry has looked at the marketing. Next year, a Rutgers economist will be investigating that, along with capital inputs and environmental challenges, to go along with the variety breeding program.

Molnar says that there is also a serious notion that the hazelnut could be grown as an oil crop. The kernel, on average, has about a 60 percent oil content, and the nuts of some plants contain up to 75 percent. No one has bred the plants for oil content, but it is seen as a potentially serious competitor to soybeans for that purpose, and Molnar’s program is also going to isolate plants that are the best oil producers.

“It’s an oil crop, whether it’s for food or for other uses,” he says. The range of potential uses runs from biofuels to lubricants, and the oils have a different profile from soybeans, which could lead to entirely new arenas. He currently has a grant from the Northeast Sun Grant Institute of Excellence, funded by the U.S. Department of Transportation, to look into this.

Whatever the use, Molnar thinks this area is destined to have hazelnut farms, and that would be a fitting role for one of America’s hardy native plants.

Don Dale is a freelance writer and a frequent contributor. He resides in Altadena, Calif.