This fact sheet has been produced with the latest information available at the time of publication. In no way, however, can this sheet be considered the ultimate in information for New Zealand growing conditions: it is just a basic guide on the subject. If you have information to contribute, or feels that any of the information is misleading, then we ask you to contact us using the Comment facility at the foot of this work.

HAZEL- Corylus avellana

Introduction

Hazelnuts are produced on bushes and small trees of the 10 Corylus species
spread through temperate forest areas of Europe, Asia and North America. Native
peoples living in their natural habitat ate the nuts of most species, but modern hazel
production is largely based on selections of Corylus avellana, native to Europe
and Asia Minor.

The Plant

In its natural form the hazelnut is a deciduous, monoecious, multi-stemmed bush. When
grown for commercial purposes it is usually grown as a single trunk tree about 5m in
height. The rounded doubly serrate to weakly lobed leaves 5-12cm long that come to a
sharp point are in alternate pairs. The male catkins and bud-form female flowers
(which have only the red stigmas prominent) are on the same tree but except for some
rare cultivars are incompatible and inter-compatibility between varieties frequently
occurs. The fruit is a nut surrounded by a 2 bladed tubular husk.

Some cultivars drop their nuts at maturity. Most sucker freely at the base with nuts
only on the outsides so this is why they are able to live almost indefinitely. The
Turkish filbert Corylus colurna does not sucker so are being trialed as
rootstock.

Climatic requirements

Hazels are tolerant of a wide range of climates but grow best where rainfall is well
distributed through the main period of growth (September to January). They like
regular high humidity and desiccate rapidly in hot, dry conditions. Good shelter is
required for high yields and irrigation will be necessary in drier areas. Dry weather
during harvest (February to early April) is useful to ensure a quality nut and ease of
harvesting.

Prolonged damp conditions in winter can inhibit pollen dispersal. The need for winter
chilling has probably been over-emphasised in the past. Varieties vary in their
chilling requirements, with some of the Italian varieties requiring very little
chilling to set good crops.

In general, hazels will crop well in climates where apples crop well. They are
tolerant of cold conditions (to -13°C) when dormant, but fruiting buds, especially
open catkins, can be damaged by frosts of -7°C.

Soil requirements

Hazels require a deep, fertile soil to crop well. They are tolerant of lime-rich soils
and prefer a pH of 6 to 7. They are more tolerant of wet soils than say chestnuts.

Fertilisation

Land to be planted should be soil-tested and base fertility built up prior to
planting. High analysis fertilisers can burn the roots of young trees if applied in
the planting hole at planting – light surface dressings only should be applied. Early
fertiliser applications should be designed to encourage rapid growth with most
balanced NPK fertilisers being suitable. On porous sandy soils, split dressings may be
safer than one heavy dressing.

Once nut production begins, fertiliser applications should be applied in early Spring
based on leaf analysis. These should be based on mid-shoot leaves sampled in January.

Nutrient levels in leaf analyses should be in the following range (based on Oregon
standards):

Nitrogen 2.2 – 2.4% Manganese 25 – 800 ppm

Potassium 0.8 – 3.0% Iron 60 – 400 ppm

Phosphorous 0.13 – 0.6% Copper 2 – 50 ppm

Calcium 0.6 – 1.5% Boron 30 – 75 ppm

Magnesium 0.24 – 1.0% Zinc 15 – 80 ppm

Orchard management

Basic principles of orchard design (eg adequate shelter, room to turn machinery, etc)
apply as for any tree crop. Close spacings maximise early returns. For vigorous
varieties, a 5 metre by 3 metre spacing (666 trees/hectare) will need to be thinned to
a 5 x 6 spacing by year 10. Low-vigour varieties, such as Whiteheart, can remain at 5
x 3 spacing for longer. Research work in New Zealand is now looking at even
closer-spaced (eg 4m x 2m) hedgerow systems for these low-vigour varieties.

Pruning

Light is essential for the production of fruiting wood. Tree training in the first 3
years should aim for an open “vase” structure of 4-5 main branches with a single stem.

Pruning in later years should aim to keep this open structure and ensure adequate
light penetration to the centre of the tree. They bear on strong 1 year wood so weak,
short growths can be removed. Remove inward growing branches that will cause shading
and cut out crossing growths. The aim is to maintain an open, well-lit tree.

Many pollinators used in New Zealand grow rapidly into large trees and significant
shading of adjacent crop trees can occur. To prevent these pollinators from occupying
an excessive proportion of the orchard canopy, the pollinators can be restricted to 2
to 3 main branches and pruned hard each year.

Hazels sucker, and these must be removed to maintain a clear trunk. (Sucker control
can be either physical, or by chemical means with desiccants, such as Paraquat.)

Pruning should take place in winter. If done during flowering, the growths with large
numbers of flower buds can be easily seen.

Pollination

Hazels are wind-pollinated during winter, so pollinator trees need to be distributed
throughout the orchard to allow wind dispersal. You must also ensure that catkin
pollen-shed timing coincides with the time the female flower of the main nut producing
cultivars is receptive to the pollen. Not all cultivars are compatible even though
they flower at the same time. The specific pollinators used for each variety are
listed with the variety descriptions.

The time of pollen shedding is influenced by seasonal temperatures and varies slightly
from year to year. Usually 2 or 3 pollinator varieties are used in commercial orchards
to cover the flowering period, with a predominance of pollinators covering the later
part of the flowering period.

Pollen grains of hazelnut are very small so they are carried very easily by wind over
long distances though pollen concentration decreases rapidly at 14 to 21 metres from
the dispersal site. Male flowers can be identified as catkins that elongate to about
twice their length during pollen shedding. Each catkin produces between 4 million and
40 million pollen grains.

Stigmas are receptive for at least from emergence from the enclosing bud scales (red
dot stage) till darkening and withering of their surfaces. Pollen tube growth within
the style is very rapid being completed within four to ten days. Female flowers have
stigmas which look like red hairs through the tips of the bud. Females remain
receptive for several weeks but male pollen has a shorter life

Pollinators can be distributed through the producing trees (usually every 6th tree in
every 3rd row) or planted in specific pollinator rows (enabling easy separation during
harvest) with every 5th row being a pollinator row. Every producing tree should be
within 30 metres of a pollinator.

Propagation

Hazels are propagated mainly by layering or taking suckers from stools of known
varieties. They can be grafted (usually on to seedling rootstocks) but the rootstocks
affect tree performance, giving variations in yield.

Tissue culture looks promising. Hazelnuts do not reproduce true to seed.

Pests and diseases

Hazels are attacked by a number of pests and diseases, most of which have not been
definitely identified or studied in New Zealand.

Big Bud mite can be a major problem on susceptible varieties in drier areas, causing
buds of current year’s growth to swell and deform then die in the spring, seemingly
especially those destined to be female flowers. Control by removing and burning
infected buds, or by spraying with Endosulphan or other systemic insecticides.

The green shield beetle feeds on maturing nuts prior to and during harvest, leaving
kernels distorted and with a bitter taste. To produce good quality nuts, absolute
control of this pest is essential. This beetle is more of a problem if native bush is
close by.

The limbs and trunks of hazels are attacked by a number of boring insects, the most
common being the lemon tree borer. The economic effect of these borers has yet to be
assessed. Good management practice in removing weakened branches may help. Vigorous
growers such as Barcelona will soon callous over.

High aphid populations can slow the growth of hazels, as aphid secretions encourage
Black Sooty Mould in the wood. Lime sulphur in the dormant season cleans this up. Leaf
roller caterpillars can cause damage to the shell of immature nuts.

Hazels can be attacked by a number of fungal and bacterial diseases, but most
commercial varieties have varying resistance to most of these. The most important
economically is Hazel Blight. Young trees of susceptible varieties and trees under
stress are most severely affected. It is easily controlled with copper sprays.

Problems

Two common problems are seedless nuts or blanks and brownstain disorder.

The drop of these seedless nuts together with their husk occurs form the beginning of
January in the case of brownstain and one month later for blank nuts and continues up
through harvest. The causes put forward to explain this phenomenon are numerous though
seemingly not caused by lack of pollination or fertilisation. The percentage of
seedless nut is a variety-dependent characteristic as well as cultural practices. A
water deficit could be related or the type of soil. A good nutrition in potassium
could reduce the number of blank nuts.

Harvesting

Hazels are left to fall and are harvested off the ground. Ground management is crucial
if machinery is used to collect the nuts – a level surface free of long grass is
required. Vacuum harvesters are used to suck the nuts off the ground surface, usually
after raking or sweeping into windrows.

Harvest is over 3-4 weeks for each variety, running from February through to April for
later varieties. Nuts can be left on the ground as long as conditions are dry but
deteriorate rapidly if left in damp conditions for any length of time. Once harvested,
the nuts must be dried to a moisture content of 7-8% and stored in a cool, dry
location.

Cultivars

There is a wide range of local and overseas cultivars available in New Zealand.

Growers should ensure that the cultivar they select is suitable for the market they
plan to supply and for the climate in which they are grown.

Harsh winter and late frost areas should not be planted with cultivars that come into
leaf early.

Humid summer areas should avoid cultivars susceptible to botrytis or those with a
heavy fibre cover.

  • Appleby

Variety of low vigour, spreading tree form, moderate suckering, with good yields.

Budburst in early September.

Flowers early, catkins shed pollen early but are prone to disease.

Pollinators unknown, but possibly Campanica, Butler, Davianna and Merveille

de Bollwiller could be used.

Nuts small, round or oval in shape flattened on two sides.

Shell) is thin, dark coloured. Kernel fills the nut well.

Kernel variable in shape (round to oval), generally lacks fibre, blanches well.

Good flavour.

Susceptible to bacterial blight, Gloeosporium on the catkins, moderately susceptible
to Big Bud Mite.

Yields a reasonable nut for the kernel market.

  • Alexandra

Vigorous variety, spreading tree form, with few suckers.

Budburst is late.

Flowers late, catkins release abundant late pollen.

Pollinators unknown, possibly Merveille de Bollwiller.

Nuts medium in size, blocky and very flattened on two sides.

Shell is thick, rather downy, generally of poor appearance.

Kernel long, flattened on two sides, slight fibre cover.

Does not blanch. Good flavour.

Moderately susceptible to blight.

Grown primarily as a source of late pollen for Whiteheart and Merveille de Bollwiller.

A high proportion of green, blank nuts fall early.

  • Barcelona

Vigorous variety, semi-spreading tree form. Moderate suckering. High yields.

Budburst in early September. .

Mid-season flowering, pollen released early.

Pollinated by Butler, Segorbe, Daviana and Merveille de Bollwiller.

Nuts medium to large in size, round, slightly flattened on two sides.

Shell is thick, rather downy, dark brown.

Kernel irregularly shaped but generally round with moderate to abundant

amounts of fibre.

Blanches reasonably well.

Excellent flavour, especially when roasted.

Susceptible to bacterial blight, botrytis and brown stain,

A high yielding variety, the main hazel cultivar grown in Oregon.

  • Butler

Vigorous variety with a semi-erect form, few suckers.

High yields. Buds open late.

Flowers rather late, abundant pollen released early-mid season.

Pollinated by Merveille de Bollwiller, Segorbe, Alexander

Nuts large, rather blocky, falling free.

Shell is thin, attractive.

Kernel oval with a light fibre cover.

Sweet tasting.

Susceptible to Big Bud Mite.

Used as a pollinator for Barcelona, Campanica, Nocchione and Ennis.

  • Campanica

Vigorous variety with a semi-erect form, moderate suckering.

High yields.

Budburst is early (mid-August).

Flowers early, produces abundant pollen.

Pollinated by Butler, Nocchione, Tonda di Giffoni and Ennis.

Nuts medium to large, round with a glossy. striped shell of medium thickness.

Kernel is round. with slight fibre.

Blanches well, excellent flavour.

Susceptible to botrytis and Big Bug Mite.

A very productive variety for warm, dry areas.

  • Daviana

Vigorous variety with an erect form, few suckers.

Rather low yields.

Flowers mid-late season. Abundant pollen produced mid-season.

Pollinated by Merveille de Bollwiller.

Nuts medium, oval with a light coloured, glossy shell. Shell thin.

Kernel roundish, slight fibre with a high yield after shelling.

Sensitive to Big Bud Mite.

Used in Oregon as a pollinator for Barcelona, but is being replaced by Butler.

  • Ennis

Trees of medium to high vigour, few suckers.

High yields.

Budburst is late.

Flowers late but releases its pollen during mid-season.

Pollinated by Butler (early flowers only), Lansing and Merveille de Bollwiller,
Alexander.

Nuts large, slightly oval with a thin, pale, attractive shell.

Kernels are round with very little fibre.

Sweet flavour.

Moderately sensitive to Big Bud Mite.

This is recommended as the best commercial nut for the in-shell market.

There is a tendency for a proportion of the crop to fall early as green blanks.

  • Lansing

A vigorous variety with an erect tree form. Yields well.

Buds open in early September.

Flowers and pollen release are in mid-season.

Pollinated by Merveille de Bollwiller and Tonda di Giffoni (early flowers only).

Nuts are large, round with a thin-shelled, attractive, ribbed shell.

Kernels have light fibre, round with a good flavour.

Susceptible to botrytis

A attractive table nut.

  • Merveille de Bollwiller

A vigorous variety with semi-spreading tree form and few suckers.

Low – moderate yields. Buds open late.

Flowers late, excellent pollen released mid – late season.

Pollinated by Segorbe (early flowers only), Alexandra, MT 18-114 and H/11H/1102.

Nuts are large – medium, conical. Shell is thick, glossy.

Kernels are round, free of fibre, blanching well with an excellent taste.

A very healthy cultivar with excellent pollen vigour but with a low yield in many
areas. Overseas literature recommends this variety for very cold climates.

  • MT 18-114 / MT 12-23

Vigorous varieties with an erect form. Moderate to low yields. Late bud burst.

Flowering and pollen release are in mid-season.

Pollinated by Merveille de Bollwiller and Segorbe.

Nuts are very large, slightly oval with an attractive, light shell.

Kernels are round to oval, with light fibre and a sweet flavour.

MT 12-23 may be susceptible to botrytis.

Two selections with attractive nuts suited to home gardens.

  • Nocchione

A variety of moderate vigour, spreading form, suckers freely.

High yields.

Buds open in early September.

Flowers mid-season, abundant pollen released early in season.

Pollinated by Butler, Lansing, Merveille de Bollwiller, Campanica (early flowers
only), Segorbe.

Nuts are medium sized, round with a marked lateral groove thick shelled.

Kernels are round with definite grooves, slight fibre, moderate blanching.

Moderately susceptible to botrytis.

  • Plowright

A variety of moderate vigour, erect form, few suckers.

Early yields under commercial conditions indicate that moderate to good yields can be
expected.

Late Budding.

Flowers late, releases pollen late.

Pollinators unknown, but probably Merveille de ‘Bollwiller, Alexandra, Segorbe.

Nuts are medium sized, round with a marked lateral groove, shell of medium thickness,
pale in colour. Kernels are round with a slight groove, pale skinned, lack fibre, do
not blanch. Moderate taste.

A strong growing Kentish Cob seedling. This selection is suited to growers wanting an
upright tree form casting light shade.

Can be used as an early pollinator for Whiteheart.

Probably suited more to humid climates than hot dry climates.

  • Tonda di Giffoni

Vigorous variety of semi-erect shape, suckers readily. High yields.

Has an early bud burst.

Flowers mid-season, heavy mid-season pollen release.

Pollinated by Barcelona, Tonda Romano, Segorbe.

Nuts of medium size, round with a marked groove.

Shell medium thickness, striped and attractive.

Kernel is round, often with a definite groove, slight fibre, blanches well.

Susceptible to botrytis.

An excellent and versatile variety suited to hot dry climates

Not suited to areas with harsh winters.

  • Tonda Gentile delle Langhe

Variety of moderate to low vigour, semi-erect shape, moderate suckering.

Yields low in New Zealand,

Early bud burst.

Flowers midseason, weak pollen released midseason.

Pollinated by Barcelona, Segorbe., Merveille de Bollwiller

Nuts small, round, often of 3 pointed appearance.

Thin shell, rather dull in appearance, dark brown.

Kernels small, clean, blanching well.

Has an excellent flavour.

Susceptible to botrytis, bacterial blight, bud mite.

Nuts of this variety are sought after by European chocolate makers for its fine
flavour. However, it requires a dry, mild climate.

  • Tonda Romano

Variety moderate vigour, semi-erect form, strongly suckering. Good yields.

Budburst in mid-September.

Flowers and pollen release midseason, pollen rather poor quality in damp climates.

Pollinated by Tonda di Giffoni, Barcelona, Merveille de Bollwiller.

Nuts small and round, dull brown shell of medium thickness.

Kernels small, slight fibre, blanches moderately well but has an excellent flavour.

Slightly susceptible to bacterial blight and big bud mite.

  • Webbs Prize Nut

A tree of moderate vigour, semi-erect shape, moderate suckering.

Yields well, buds open late.

Flowers late, pollen released rather late.

Pollinated by Merveille de Bollwiller, possibly by Alexandra, Segorbe.

Nuts are medium-large, long with a light coloured shell of medium thickness.

Kernels long, pale, clean with a good taste.

Susceptible to bacterial blight.

A filbert-type nut. The nuts fall mainly in the involucre but are easily extracted.

Possible use as a late pollinator for Whiteheart and Merveille de Bollwiller.

  • Whiteheart

A tree of low vigour, semi-erect shape, strong suckering.

Good yields under commercial conditions

Buds open late.

Flowers late, pollen released mid-season.

Pollinated by Merveille de Bollwiller, H/11H/1102, Alexandra, Plowright and

possibly Webbs Prize.

Nuts are small – medium in size, brown, glossy, thin shell.

Kernel is round with a small groove, pointed, clean (no fibre), blanches very well.
Excellent flavour.

Susceptible to big bud mite

An excellent nut for the kernel trade, but recommendations limited by lack of
knowledge of yield of mature trees.

Well suited to humid climates.

  • White-skinned Filbert – Wispit – Nottingham

Three cultivars of similar nut and tree characteristics.

Form bushes of low vigour, spreading form, numerous suckers.

Moderate to high yields. Buds open late.

Flowers mid-season, pollen released mid-season.

Pollinators unknown.

Nuts medium – small, long (Filberts), tightly held in the involucre.

Kernels long, free of fibre, strong hazel flavour.

Susceptible to bacterial blight, big bud mite.

Although giving good yields of tasty kernels, Filberts are tightly held requiring an
extra operation to extract them from the involucre.

Yields

Yield data for mature orchards in New Zealand is not available yet. Yields rise
rapidly from up to 500 grams per tree in year 4, to 1 to 2 kg per tree by the 6th
year, and 4 to 8 kg per tree by year 10. The average yield of well-run overseas
orchards is in the range of 2.5 to 3 tonnes per hectare (3.5 to 4.5 kg per tree at a 5
x 3 metre spacing). Yields of at least 2.6 tonnes per hectare are needed to be
economically viable.

Commercial potential

Hazels are traded mainly as kernels, providing a ready-to-use product for the retail
trade, bakers, and confectionery manufacturers. Hazels for this trade are usually
small with round, clean kernels, and a strong hazel flavour. The ability to blanch
easily (blanching is the removal of the brown skin, leaving a white kernel) is seen as
a highly desirable attribute for this trade.

The in-shell trade makes up less than 10% of the world hazel trade and is less
demanding of kernel quality, requiring only a tasty kernel with a minimum of corky
fibre. Nuts are usually large with attractive shells, and should be easily cracked.

Markets

Hazels are one of the 3 main nut crops worldwide, with an average annual crop of
around 500,000 metric tons being comparable to walnuts and almonds. Prices are
influenced by the yield of all three nut types. There is a worldwide trend towards
increased nut consumption as the health benefits of nuts are promoted, so the small
New Zealand market can be expected to grow.

At present, NZ growers are receiving $3.50 to $4.00 per kg in-shell. As supply moves
closer to demand, this can be expected to fall to a level similar to that obtained by
growers in Oregon, around $0.80 to $1.50/kg at the orchard gate (prior to drying).

South Island growers have a ready market where the crop can be sold and processed. It
is hoped the North Island will have some machinery for cracking soon.

References and other contributors:

Murray Redpath: Cultivars in NZ notes

David McNeil: NZ Tree Cropper Articles

Krussmann: Cultivated Broad-Leaved Trees & Shrubs,

FAO Research Network on Nuts, Number 4, December 1995

AGFacts, NSW Agriculture, Internet site

First published March 1997. Updated March 1999

 


Believed to have been maintained under the guidance of Roy Hart.
Edited by Gail Newcomb.
Last updated 1998 by Murray Redpath.
Re-available on-line December 2012.
Original accompanying information to be formatted and appended as opportunity permits.

 

NZTCA ORCHARD HAZELNUT CALENDAR

Month:JFMAMJJASOND
LeafingX
Flower (F)XXXX
Catkins (M)XXXX
PruneXX
FertiliseXX
MowXXXXXXX
Weed
Control
XXXXXXX
Control Looper
Leafroller
Cater-pillar
Grass Grub
XXXXXXX
Control Big Bud MiteXX
Prepare HarvestX
Propagating woodXXXXX
Record
Keeping
X
Harvest
Dry
Store
XXX
DeliverXXXXXX

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