Lincoln University trial block: plant growth and development

The weekend started at Lincoln University. Clive Kaiser, who has recently been appointed Associate Professor of Horticulture, talked us through plant responses to pruning and the influence of growth hormones and environmental factors.

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The Highs and Lows of High Density Orchards

Reproduced from 2018 Growers Handbook: Nut Growers Society of Oregon, Washington & British Columbia – 103rd Annual Meeting, January 18 2018, pp85-89

A panel discussion with Jeff Newton, Lance Kirk and Rich Birkmeier. Moderated by Jeff Choate (OSU Extension)

Summary (HGA editor)

US orchardists have been experimenting with double density planting since the 1970s. Trees are planted more closely together than the intended final spacing, to increase per-hectare yields while the trees are still growing to mature size. The temporary trees are removed once the trees start to grow together.

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Opportunities for expansion of the NZ hazelnut industry

By Murray Redpath

HGA newsletter, February 2009

The New Zealand hazelnut industry is steadily establishing itself as an economically viable horticultural industry. With over 400 hectares planted, the increase in hazelnut production over the coming years will enable the existing cracking plants to take advantage of the expanding market for nuts. This market expansion is being led by research that is showing the health benefits of including nuts as a daily part of one’s diet. Research is continuing to prove that the nut oils are heart friendly, rapidly lowering levels of bad cholesterol, and recent research is indicating that they may also be useful in preventing diabetes.

The expansion of hazel growing out of the main Canterbury area has indicated the potential for hazelnut production in many areas that are now dominated by livestock production. In recent years the dairy boom has made it difficult for other land uses to attract attention but there is potential for a significant hazelnut industry in the sheltered, moister areas of South Canterbury, the lower Waitaki, and coastal Otago. Examination of new plantings and old stands indicate that the best sites have growth rates as good as in the main hazelnut producing areas overseas. Compared to dairying or intensive livestock production, hazel growing has lower total water use, no effluent disposal costs, and lower energy input costs. Nuts are machine harvested so seasonal labour requirements are not an issue.

The majority of hazels planted in New Zealand are the Whiteheart variety, selected for its high quality kernel. Grower success with this variety has been mixed, with many experiencing poor yields and high losses of young plants in some soils. The Hazelnut Growers Association of NZ (HGANZ) and the NZ Tree Crops Association have been working to identify the causes of these problems, running field days on pruning, orchard management, and testing young trees for disease. Poor pollination has been identified as the probable cause of poor yields and assistance from the Sustainable Farming Fund is enabling us to provide accurate advice to growers through a series of workshops in June of this year.

The Oregon hazelnut industry is a highly profitable horticultural industry concentrated on the high quality soils of the Willamette Valley. With returns of about $US7000 per hectare over cash costs, hazelnut production competes well with other land uses. Production is concentrated in the northern part of the valley between Salem and Portland, an area with large areas of grass seed cropping, berry growing, ornamental tree nurseries and wine grapes, especially pinot noir. Having watched the changes in the Oregon industry over the last 15 years, I had the chance to examine it during a visit in August/September of 2008 and see if there were lessons for the NZ industry.

The Oregon hazelnut industry has always been based on providing high quality nuts for the world inshell nut market. Fifteen years ago the traditional in-shell markets (Europe and domestic US consumption) were declining and the focus for hazelnut production was turning to the dominant kernel market. The situation has changed with the rise of China as a dominant economic force and about 50% of the total US in-shell hazel production now goes to China and Vietnam, often with prices negotiated and contracted prior to harvest. Processing plants in Oregon are keen to promote extra hazelnut production.

Both of the preferred in-shell hazel varieties, Barcelona and Ennis, are susceptible to Eastern Filbert Blight, a disease that has been spreading through the Willamette Valley since the 1980’s. This has restrained new plantings as growers wait for EFB-resistant varieties to emerge from the Oregon State University breeding programme. Recent years have seen resistant varieties emerge for the kernel trade but the first EFB resistant in-shell variety was not released until January this year. Oregon growers have a huge replanting task. Larger growers that we visited are replanting 10,000 trees per year.

The markets that the Oregon industry is supplying would be open to New Zealand growers if they had the right varieties. Good quality Barcelona and Ennis nuts are already being grown in Marlborough but quantities are not yet sufficient to fill local market requirements. The opportunity exists to expand our hazelnut plantings to take advantage of profitable markets for healthy food and growth in Asian economies.

Healthy Hazelnut Oil

HGA newsletter, autumn 2004


Hazelnuts have found their way into more non-traditional foods due to the recognition of its nutritional and nutraceutical properties. Among nut species, hazelnuts play a major role in human nutrition and health because of its special composition of fatty acids ( mainly oleic acid), fat soluble bioactives ( tocopherols and phytosterols), vitamins (vitamin E), minerals, amino acids, antioxidant phenolics and dietary fibre. Hazelnuts provide an excellent source of energy (631 kCal/100g) due to its high oil content (~61%). Besides nutritional value, the presence of taste-active components together with aroma-active components can improve the taste and flavour of hazelnut-based products.

The presence of palmitoleic acid allows hazelnut oil to be absorbed quickly into the skin as well as acting as a solar UV filter, thus making it an excellent carrier oil and ingredient in skin preparations.

Elevated serum cholesterol level is a well-known risk factor for coronary heart disease and is a leading cause of mortality in many countries around the world. Monounsaturated fatty acids which are in large quantities in hazelnut oil, are known to decrease the low-density lipoprotein cholesterol levels and decrease the risk of heart disease. Research has demonstrated that hazelnut supplementation (40g) in the diet results in total cholesterol, low-density lipoprotein cholesterol, very low-density lipoprotein cholesterol, triacylglycerol Apo B and homosistein reduction of up to 5.3, 2.6, 22.4, 5.3, 0.3, 10.4, and 7.8% respectively. Furthermore, hazelnuts in the diet increases high-density lipoprotein cholesterol and Apo A by 13.9 and 0.3% respectively.

F.Shahidi, Dept. of Biochemistry, Memorial Univ. of Newfoundland, and C. Alasalvar, Dept. of Biological Sciences, Univ. of Lincoln, Brayford Pool, United Kingdom.

Local Research – Hazelnut Oil Composition and Comparisons

The quality of cold pressed hazelnut oil extracted from a mixture of Merville de Bollwiller, Ennis, and Butler hazelnuts grown at ‘The Nutt Ranch’ in Marlborough, was determined by measuring lipid classes, and fatty acids. The oil was tested at Hort. Research in Auckland during September of 2004. The reasons for having our oil tested were:

  • To be able to give more accurate information about our own products to our customers.
  • To make a comparison of the fresh hazelnut oil from our orchard, grown and pressed in Marlborough, with hazelnut oil from other parts of the world.
  • To compare the fatty acids that make up hazelnut oil with virgin olive oil.

The total lipid content, by weight, of the hazelnuts being tested was 48.3%. This is slightly lower than the actual figure due to some oil loss within the extraction equipment. Seven fatty acids were identified by chromatography, among which oleic acid contributed 77.839% to the total, followed by linoleic, palmitic, and stearic acids. Unsaturated fatty acids accounted for 93.183% of the total fatty acids present. Saturated fatty acids made up only 6.817% of the total fatty acids and were composed of palmitic acid and stearic acid.

Fatty AcidClassHazelnut oil sample tested
(oil %)
Comparison with virgin olive oil
(oil %)
International norm for hazelnut oil
(oil %)
16:0 (palmitic acid)Saturated4.614%10.930%4-9
16:1 (palmitoleic acid)Unsaturated0.143%1.158%Max 0.3
18:0 (stearic acid)Saturated2.203%1.981%1-4
18:1 (oleic acid) (=Omega-9)Unsaturated77.839%72.294%70-85
18:2 (linoleic acid (=Omega-6)Unsaturated14.925%9.211%7-25
18:3 (linolenic acid) (=Omega-3)Unsaturated0.143%0.793%Max 0.6
20:1 (gadoleic acid)Unsaturated0.133%0.313%Max 0.3


We were extremely pleased with the results of our data as it shows good consistency with fatty acid measurements internationally. All of the different fatty acids were well within the international norms. The data gained, as well as the investigation of the makeup of our oil will help us in answering questions about the fatty acid content of our oil by interested customers in a more informed way. We found it very interesting that hazelnut oil compares extremely well with Olive oil, the best part, of course, being able to ingest the oil in the form of fresh hazelnuts or as cold pressed oil. We were amazed at the amount of research being done on Omega-3 fatty acid, Omega-6 fatty acid, and Omega-9 fatty acid internationally. The uses that our body makes of each of these are pretty incredible and it is notable that we can only get Omega-3 and Omega-6 within our diet. Our body is able to manufacture a limited amount of Omega-9 but most of what we need must still come from within our diet.

And finally, aside from the fact that hazelnut oil has super health giving properties, it also has a terrific aroma and taste. It is an excellent replacement for butter on potatoes and vegetables and is perfect for use in baking where an oil is called for.

DW & BL Null, Nutt Ranch Products, Marlborough, New Zealand

Flowering and pollination

By Murray Redpath

HGA newsletter September 2011

The warm autumn experienced this year has highlighted the importance of current research into flowering and pollination behaviour of different cultivars at different locations around the country.

  • In South Canterbury (Geraldine), Lansing was in flower in mid-July but of the others only Butler had any flowers. Merveille, Alex and Whiteheart were shedding pollen from early July at least. By late August, there was still some flower on Butler, Ennis and MT18/114 but Lansing flowering was over. Merveille pollen was finished but Alexandra and Butler were still shedding.
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The NZ hazelnut industry. Where to from here?

By Murray Redpath

HGA newsletter October 2010.
Originally presented at HGANZ AGM, 2010

NZ hazel industry 2010:

NZ has over 430 hectares planted, most since 2000. Almost 100% of this area is planted in Whiteheart plus pollinisers so we have an industry dependent on successfully growing and marketing Whiteheart.

There has been a change in the orchard size since 2000 – from mainly orchards of 200-1000 trees to mainly orchards of over 1000 trees (see graphs below).
Fig. 1: Number of hazel trees per grower, SNGA hazelnut seminar 1996 (McNeil, 1996)
Percentage of attendees
60 50 40 30 20 10 0

<200 200-399 400-999 1000->2000 1999
Orchard tree number

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