Description
I am pretty sure most everyone reading this blog will be familiar with hazelnuts. They are one of the more popular nuts and are primarily used as food, either whole or as a flavoring for products like chocolate truffles or in coffee and spreads. What might be less well known is that hazels are a member of the birch family and have been cultivated by humans for over 8000 years!
The vast majority of hazelnuts are produced by a plant known as Common Hazel or European Hazel (Corylus avellana). This variety of hazel is primarily grown in Europe with Turkey producing over half of the worlds supply of hazelnuts.
In North America common hazelnuts are are primarily grown commercially in the states of Oregon and Washington because, unlike the Eastern half of the United States, this area was not yet affected by eastern filbert blight. Unfortunately, this blight has now reached these previously untouched areas and is starting to kill these commercially grown trees.
Enter the hybrid hazel. These hybrids are usually crosses between the American hazel (Corylus americana) and the common hazel. Some breeders have also used the beaked hazel (Corylus cornuta) as part of their crossing program. The American and beaked hazel both have significant resistance to eastern filbert blight and are more cold hardy but they produce nuts that are far too small for commercial production.
Significant breeding work has been done on hybrid hazels by several different groups. Notably the Badgersett Research Corporation, Mark Shepard, Arbor Day Foundation and Rutgers University. However, there are many others working on this project as well.
The breeding has been focused to provide the best mix of attributes of both species. The primary objective has been to produce a hazel with eastern filbert blight resistance and increased cold hardiness while still maintaining a fairly large nut size. A secondary characteristic that they are breeding for is machine harvestablitity to increase the potential of these hazel hybrids being used as a commercial crop.
The hybrid hazel is a medium to large shrub that grows from 10-16 feet tall and with a width of 5-8 feet. As mentioned earlier, it produces nuts similar although perhaps a bit smaller than common hazelnut. It has a dense fibrous root system with no tap root and the ability to thrive in a variety of conditions. A lot of the breeding has been done in Michigan which is known to have brutally cold winters. Due to this cold location, the hybrid hazel can usually be grown in zones 4-7 but, depending on the specific variety, zone 3 is also a possibility.
Uses
When people think of hazels they often focus on the nut. This tasty morsel, as motioned earlier, is used in a variety of food products. By dry weight. the nuts are generally 58% oil, 22% carbohydrate and 17% Protein. Although the source I found did not directly say it, I imagine the other 3% is mineral weight.
Hazelnuts / This sort of nutritional profile makes hazelnuts very compelling as food for both humans and animals. Of particular interest is the oil content which some have suggested makes hybrid hazel a potential perennial replacement for soybean crops. Many sources are claiming that, once established, hazels can produce similar amounts of oil to soy on the same acreage with far fewer inputs.
Many other drawbacks of annual agriculture would also be reduced; little to no fertilizer and toxic sprays would be needed. One of the biggest environmental issues today, that is rarely spoken about in the mainstream, annual tillage, would also be eliminated.
The oil, once pressed from hazelnuts, is a great cooking or flavoring oil. Some have even suggested that it could also be used to make bio-diesel. The hazel meal left over from pressing can be used as a component of animal feed, boosting protein and carbohydrate.
Due to the dense fibrous root system, hazel hybrids also sequester carbon, particularly in the root system, while stabilizing the soil and preventing erosion. The above ground portion of the plant provides animal habitat and, if planted as a perimeter hedge, could act as a wind break.
After about ten years the above ground growth and nut production will slow but can be reinvigorated by coppicing. This makes hybrid hazel a great biomass crop as well. On a large scale it could be used to make bio fuel while on a smaller scale it could be used for firewood and mulch.
Growing Conditions, Propagation, and Maintenance
Hybrid hazels seem to be mainly propagated by seed but work is also being done with vegetative propagation. In the wild, American hazels often propagate by suckering and some hybrids are noted for this trait so there may be potential in this area. Seedlings can be planted in late spring to early summer and the best conditions to do so are cool and moist.
Hybrid hazels will produce the most in full sun but American hazel is a forest edge plant that does well in partial shade, therefore the potential of hybrid hazels to be grown in partial shade is favourable. Some sources also show reasonable nut production in partially shaded circumstances. Hybrid hazels do not need fertilizer but will likely produce a larger nut crop if fertilizer is used.
This is a very adaptable plant that will grow well in soils ranging from heavy clay to sandy silt. PH ranges from 5.5 to 8. Once established they may need as little as 20 inches of rain a year.
These plants are generally not bothered by disease or insect pest. Birds and mammals, like squirrels, can pose more of a problem because they are tempted by the tasty nuts, but as the size of the planting increases the percentage of nuts stolen decreases. Deer do not prefer hazel as a browse but can pose a problem to initial plantings; after a few years, as the plants get larger, they will do little damage. It also helps to keep the hazels far from forest edges and to keep the ground under them well trimmed. Human activity will also help to deter animal pests.
Hybrid hazels are monoecious which means they have male and female flowers on the same plant. The male flowers are catkins which open in the winter and flower into the spring. The female flowers are tiny and hard to spot. Pollination is almost exclusively by wind and it is important to have two or more varieties in close proximity as plants cannot pollinate themselves. This shouldn't be a problem if you are growing seedlings.
Over time, the hazel bushes may grow too large for your liking or become unproductive due to excessive old and dead wood. At this point, best practice is to coppice them to the ground. This will refresh and invigorate the plant. They will be back to full production in 2-3 years. The root system will probably live for 100 years or more.
Sources and Resources
There are a couple of good PDF's in here.
- https://www.extension.umn.edu/environment/agroforestry/components/hybrid-hazelnuts.pdf
- http://www.badgersett.com/sites/default/files/info/publications/HH1.pdf
- http://www.badgersett.com/info/hazelnuts
- https://en.wikipedia.org/wiki/Hazelnut
- https://en.wikipedia.org/wiki/Hazel
- https://www.sciencedirect.com/science/article/pii/S0926669009001393
- Ken Mudge and Steve Gabriel (2014). Farming the Woods. White River Junction, VT: Chelsea Green Publishing.
