Harvest musings

HGA newsletter 2005

A year’s worth of effort comes to an exciting but busy end as harvest is upon us. Like most things good, preparation is the key, as you never really know how it’s going to turn out until the very end.

Hazelnuts may start to fall in late February – early March with the majority fallen by the end of March. The colder nights, shorter days and warm midday temperatures in late summer cause the outer husks to swell (hot days) and then contract (cool nights) which eventually cause the nuts to drop. The leaves will also start to turn but should fall after the nuts. A bit of planning is often needed in order to get the nuts up off the ground before the leaves drop. Should the leaves begin dropping during the harvest, a leaf blower is a very useful tool.

Hazels can be harvested in a number of ways. The most common is probably by hand using rakes. But sweepers and suction equipment can improve the efficiency of the harvest. Mechanised harvesters often depend on the area under the trees to be clear of weeds, suckers and relatively firm. There are several types of harvesters being used within New Zealand.

Nuts drop naturally during a six-week period. There can be a difference of several weeks between different cultivars. After the nuts have been picked up they should be rinsed with water to remove stones, grit, and dust before drying. Hazels may have a moisture content of 12 – 15% at harvest. For successful storage the moisture level needs to be reduced reasonably quickly to 8%. To get the moisture content down quickly, a period of careful drying on ventilated or open-air racks will produce good results. Storage in 20-kilogram onion sacks in a dry area with some air movement will finish a successful harvest.

No harvest is ever easy but there is always a sense of satisfaction once it is over!!

Dave & Bev Null


HGA newsletter, winter 2003

In this issue our growers’ corner takes a look at the hazelnut operation at the Nutt Ranch in Blenheim, and we are listening to Bev and Dave Null.

This property was purchased in 1995 as 8ha of pasture land. The land was purchased with the growing of hazelnuts in mind. The land is marginal for horticulture use and is in a dry area of Marlborough.

Hazels are not deep rooted and our soil, although light and stony, is rich and has good PH. Norwesters are a bother in early summer as the hazel leaves are fairly delicate and can sustain some wind damage. We have an excellent water supply for both ourselves and our irrigation.

At present we have 3000 trees with 500 at 7yrs, 500 at 5yrs, 500 at 4yrs, and 1500 at 3 yrs.


Our main crop is a New Zealand bred hazel, “Whiteheart”. It is an excellent confectionery nut with a fine nutty flavour. It fills the shell exceptionally well and blanches nearly 100%. We have Narrowed our pollinator range over 5 years to 4 which work well for us. These are Alexandra (best), Merville de Bowiller (good), Butler (earlyish), and Ennis (earlyish).

Our tree spacings are somewhat different thanwhat most written material suggests. The Whiteheart is not a large tree and it is fairly upright. We have chosen 4 meters between rows with 3 meters between trees in the row.


We are using Nitrofoska as a general fertilizer in late Winter. The amount is based on soil and leaf testing during the previous season. Our plan is to replace what elements are used by our trees and see annual growth of between 150-200mm in the season.


We try to keep the centre of the tree open with no crossing limbs. We remove some fruiting wood from most trees to promote new growth. We shorten to an outside bud all extra long growth. We try to leave as large a framework as possible.


Our irrigation consists of 50mm mains with 40mm leaders and 19mm laterals. We are using 4litre/hour drippers which are serving us well. We keep close records on all irrigation during the dry summer. We have found that the Hazels need extra irrigation during nut formation and then again during their final maturing.

Sucker Control

The Whiteheart variety produces large amounts of suckers at the base of each tree in early summer and again in early Autumn. We spray with Buster when the suckers are young and tender but clean up the trees with the secateurs during the Winter.


Our harvest is done by hand as a family affair, but our plan is to eventually operate a vacuum running off the tractor’s PTO as the trees become larger. Our nuts are washed carefully and then dried in onion sacks in the sun to about 5% moisture content before cracking, shelling, grading and sorting. We store the shelled nuts in plastic drums until sold.

To The Future

We have just completed a commercial kitchen and a building for the processing, retailing, and storage of nuts. Next year there will be a need for a full time worker in the orchard…..the tractor needs replacing….the harvesting and shelling of the nuts must become more mechanized to speed the processing and save our backs.
We would also like to see more people sharing their experiences and knowledge. Contact with other growers and processors is extremely important for the industry.
And, of course, we wish to find the time to just sit on our veranda and enjoy the day!


We consider the marketing of our products to be as important as the growing of the nuts. Our marketing strategies are based on the quality and freshness of the products and/or their health giving properties. We sell from the “ranch”, from markets, by order, and by e-commerce through our website which has become an exciting part of the business.

Pollenizer management in a hazelnut orchard

S.A. Mehlenbacher and A.N. Miller – Oregon State University, 1988

HGA newsletter, Winter 2003

Three factors must be considered in choosing pollinizer cultivars: 1) the amount of viable pollen produced, 2) compatibility, and 3) time of pollen shed.

The amount of viable pollen produced by a hazelnut tree is largely a function of the number of catkins on the tree and the viability of the pollen produced. Some cultivars set pollen in abundance Others typically set very few catkins. Some cultivars drop their catkins prior to pollen shed. Since one good Daviana catkin is estimated to produce 4 million pollen grains, the amount of pollen produced by a single pollinizer tree is tremendous.

Incompatibility occurs when plants having functional pollen and functional female flowers are unable to set seed when self-pollinated or crossed with some of their relatives. Incompatibility is a physiological between pollination and fertilization. Pollinizers are required in hazelnut orchards because cultivars are self-incompatible. They are also cross-incompatible in certain combinations. Hazelnuts are similar to Brassica species (cabbage, broccoli, and their relatives) in that all have the sporophytic incompatibility system All pollen produced by a tree exhibits the same incompatibility reaction. The reaction is under simple genetic control. There is one locus (one gene), the S-locus (for self-incompatibility) with 22 known alleles. Don’t let this terminology scare you. In humans, there is a locus controlling eye color, an allele for brown eyes, and an allele for blue eyes. Humans have a locus controlling hair color, an allele for brown hair, and an allele for blond hair. In hazelnuts, there is one S-locus which controls the incompatibility reaction, and alleles S1, S2, S3,…..S22. Hazelnut trees, like humans, are diploids. Thus at every locus, they have two alleles. Brown eyed people may have two alleles for brown eyes or one allele for brown eyes and another for blue eyes. The allele for blue eyes is recessive. In hazelnuts, both alleles are always expressed in the female flowers. One or both may be expressed in the pollen. If a given allele expressed in the pollen is met with the same allele in the female flower, the cross is incompatible. In simpler terms, if like meets like, the reaction is incompatible. If a given allele expressed in the pollen is met with different alleles in the female flower, the cross is compatible. Because of the dominance relationships among S-alleles, some crosses are compatible yet the reciprocal cross is incompatible.

A third factor to consider in choosing pollinizer cultivars is time of pollen shed. It is essential that the pollinizer shed pollen when the female flowers of the main crop cultivar are receptive. Pollen which is shed before the female flowers emerge is wasted. Unpollinated female flowers remain receptive for up to 3 months, so a late pollinizer can be very effective. Although actual dates vary from year to year, relative dates of pollen shed are consistent. Female flowers and catkins respond differently to temperature. In colder winters, female flower development is accelerated relative to catkin elongation. Thus a pollinizer which sheds at the ideal time one year may shed too early or too late the next year. Some cultivars shed their pollen over a very short time while others shed over a much longer time. By planting 2 or 3 rather than a single pollinizer, growers increase the odds of having pollen shed at the optimum time.

Another dehiscence and pollen release from catkins requires lower relative humidity and warmer temperatures. If temperatures are too cold (320F or less) and humidity is too high (85%+) then pollen will not be shed.

Temperature will also have an effect on pollen viability. If temperatures exceed 730F then pollen viability decreases. Optimum pollen germination in artificial culture has been obtained at 68-720F, but will also germinate at 34-390F.

Once pollen is released from the anther, wind is required for its distribution. The absence of wind could result in pollen dropping to surfaces below the catkins. Theoretically, pollen could travel about 250ft. in 36 seconds and drop 3 feet. if a 15mi/hr wind was blowing. However, hazelnut pollen is moved by eddy diffusion where the air movement rolls and swirls. Pollen consentration drops very quickly to relatively low amounts around 46-72 ft. distance away from the orchard edge. At this time we do not know what the required amount of pollen is to guarantee optimum nut set and development. However, in 2 research articles Schuster (5,6) states, “In observation in the field is shows that trees planted 40-60 ft. from a pollinizer bear good crops though the ones at 60 ft. sometimes appear light.” and “In the field it has been noted that trees more than 50ft. from the pollinizer yield smaller crops than closer.”

The above article has been abridged to conserve space in our news letter. Data tables showing compatible crosses, compatible cultivars, Cultivar pollen shed compatibility, Pollen concentrations at different distances, and charts showing pollinizer planting options within orchards have been left out. If a full copy of the article is wanted, please contact the Editor.

The hazelnut tree is a wonder

Jeff Olson, Extension agent, Oregon State University

HGA newsletter, Autumn 2003

Horticulturally speaking, the hazelnut tree is clearly out of the ordinary. It is more than just nutty. It is unique and wonderful. The way in which it achieves pollination in the winter and completion of nut set in the spring, is like no other horticultural crop that I have ever heard of. It is a “one of a kind”, just like some of the people in our industry!

Over the years, many researchers have investigated the growth and development of the hazelnut, in an attempt to unlock some of the secrets of this unusual plant. In fairly recent times, 1979, Dr. Maxine Thompson, of OSU, published a very informative article about the growth and development of the hazelnut flowers and nuts. It is one of those information-packed articles that is peppered with words like: megasporocytes, achesporial cells, funiculus of the anatropous ovule…you know what I mean, light reading.

Maxine followed the development of the flower and nut from the time of pollination to harvest. And she found some fascinating things. Pollination takes place in January and February, with the wind being the pollinator. There are a pair of styles that are joined at the base by a tiny ovarian meristem. When the pollen lands on the stigmatic surface of the style, hopefully it germinates and forms a pollen tube. The pollen tube grows to the base of the style in 4 to 7 days and then it rests there until May. Four to five months lapse between pollination and fertilization of the ovary.

This research project looked at how long the stigma would remain receptive to pollen. Did you know that the stigmatic surfaces of hazelnut female flowers remain receptive for up to 3 months? This study used a controlled hand pollination to test the length of receptivity at five different stages of flower development, and found them to be viable all the way up to March 13. Those old flowers were withering and necrotic, but the stigmas were still receptive.

The clusters that had not been pollinated successfully all dropped to the ground by the end of May. The flowers that were successfully pollinated continue with the development of the ovaries that become mature by the middle of June. Fertilization of the ovaries can then take place. The nut can now develop, and it reaches full size by the beginning of August. By July the shell begins to harden, and is hard by early August.

The cells that will form the following year’s crop also form in the spring and summer, while the present crop is being set. The male flower, the catkins, differentiates at the end of May and beginning of June. The female flowers for the next year differentiate between July and September. So, you can see that there is an awful lot going on inside that hazelnut tree in the spring and summer.

Way back in 1925 Joseph Newell did a study of the bearing shoots of the filbert. He found that the number of fruiting buds was directly proportional to shoot length, with the number of fruit buds increasing as the shoot length increased. The diameter of a shoot was a good index to its length. In most cases he found that there is very little degree of negative correlation between a shoot`s angle and the number of fruit buds. He noted that better light illumination results in better production in the upper third of the tree. Of course, this observation has been verified quantitatively by the more recent work of Dr. Anita Azarenko.

Newell found that in most cases the variations of illumination on different sides of trees was insufficient to cause any consistent variability in the number of fruit buds formed on the shoots. He observed that in Barcelona, a fair degree of correlation exists between the male catkins and the number of fruit buds per shoot.
In 1957 John Painter and Henry Hartman reported that the greater the length of the shoot: 1) The greater the number of female flower clusters; 2) the greater the percentage of female flowers that had nuts set in May; 3) the greater the number of nuts in a cluster; 4) the greater the number of nuts matured; 5) the larger the nuts. Overall evidence suggests twigs greater than 6.25 inches long bore the largest and greatest numbers of nuts. Twig length did not effect distribution of blank nuts. They noted that filberts can not produce both extensive twig growth and extensive nut production in the same year, hence the alternate year effect.

In one of the few research studies on the root systems of hazelnuts that I have found, scientists in Italy exposed two adjacent halves of two neighboring trees. The trees were closely spaced at 13′ x 13′, so the roots tended to extend diagonally to the corners of a square but laterally only as far as the roots of the next tree. The bulk of the roots occurred in the 8-31 inch depths of the soil. Many feeder roots occurred in the soil directly under the trunk. The study was conducted on deep fertile soil and that had a practice of cultivating to a 10-inch depth, which were the factors mainly responsible for this type of vertical root distribution.

So, you see that the quest for understanding the marvelous hazelnut tree have been going on for decades. Significant discoveries have been made, and certainly more await discovery.

Ted Kempe

Amberley, North Canterbury

HGA newsletter, Autumn 2003

In this issue our growers’ corner takes a look at Hazelwood Hazelnuts, and in we are listening to Ted Kempe of Amberley, who is one of the pioneer leaders in New Zealand’s young hazelnut industry. Ted has kindly given us the statistics of his operations.

PlantedAugust 1989
Area3.5 acres (1.4 ha)
SoilWakanui: Comparatively shallow topsoil on a clay base.
ShelterTasman Poplars. These are compatible to a saline atmosphere.
Block sizes6 x 50m x 50m blocks
SpacingShelter Belts: 4m in rows with 5m between rows.
Headlands5m between last hazelnut and shelter belt. (Not Enough)
IrrigationPump water .5km from well. Irrigated shelter belts with 4litre drippers.
Irrigated hazelnuts with 2 x 4 litre drippers, 1m either side of the tree.
FertiliserNitrophoska TE Blue special
Weed controlRoundup with Versatil to remove clover.
Sucker controlParaquat (Gramoxone)
Block layout1 row pollinators to 5 rows Whitehearts.
Hazelnuts180 pollinators; 560 Whitehearts.

Hazelwood Mistakes

ShelterPlanted six months prior to planting hazels, resulting in wind damage.
IrrigationHigh iron content resulted in blockage of drippers. Hazels stressed due to lack of moisture.
HeadlandsNot big enough for turning machinery at end of rows.


• Whiteheart is an excellent hazel with many qualities.

• Prune to a vase shape for first two years.

• Weed control is essential.

• Nuts fall onto the ground when ripe. Eventually mechanical harvesting is necessary.

• Moisture content of harvested nuts has to be reduced from around 24% to 9%.

• Yield: Suggest 4kg at year 10 seems to be realistic.

• Beware of poplars and willows for shelter because their surface root systems will chase water (from your irrigation system) and deprive your hazels.

• Roughly allow $1.00 per kg for maintenance/growing expenses per year and $1.00 per kg harvesting costs. These costs reduce as your orchard becomes more productive. Greater productivity does not necessarily mean greater expenses.

Ted Kempe
307 Beach Road

Chairman’s report 2003

By David Murdoch, Interim Chairman

HGA newsletter, summer 2003

Welcome to all members of the Hazelnut Growers Association. The setting up of an association takes a considerable amount of time and effort and I would like to thank all those who helped get the ball rolling. The transition from Southern Nut Growers Association has been reasonably smooth and their grant of $500 is appreciated. Likewise we are very grateful for the early support from the hazelnut action group to help with some of the setup costs.

Since our inauguration the committee has had several meetings and along with the basic administration details there has been considerable discussion about the initial direction the Association needs to head in. Feed back from members indicated a desire for communication between growers, and some answers to the problem of yield variability with Whiteheart.

I am delighted with the effort that Dave Null has put in to come up with the newsletter as this is the most valuable means of communication we can have, so thank you Dave. The production of the newsletter is designed to fit in with the seasonal issues of Health in a Shell and will be sent out as an insert. This allows us to publish larger articles in the journal while catering for in house association news etc. in the newsletter.

With regards to research the committee feels the most important area to focus on at present is the yield profile of Whiteheart as there appears to be quite a variation between orchards. The committee is currently investigating past research and hopes to work with Lincoln University on any new research initiatives. However funding of any research is a major hurdle. The committee feels that perhaps the best initial step is to setup a program on a number of orchards to study such things as soils, fertilizer inputs, irrigation, pollinators, etc. etc. in an attempt to find out why some orchards yield better than others. In other words to come up with a set of best practice orchard management guidelines. We feel this could be a cost-effective way of improving Whiteheart yields. So at some stage this year we will be calling on a number of growers to help out with this.

The committee has also discussed the possibility of a hazelnut conference/seminar. This would be an ideal way to bring growers together and to disseminate information.

David Murdoch
Interim Chairman