Woodkerne Nurseries

Potentially Ireland’s most productive and sustainable source of proteinNuts whole hazelnuts! No don’t take them and cover them in chocolate. Plant them and get a bumper crop of high protein food within 5 years.

The Hazel tree (Corylus avellana) and its cultivated relative, the Cobnut, is possibly the most neglected of our food producing plants in Ireland. Hazel is more often viewed as a ‘wildlife tree’, a hedging plant or a source of small poles for the garden. Whilst it is all of these things, Hazel is much more – it provides an annual supply of protein-rich food in the hazelnut.

Its Halloween again and the nuts are in the shops. Ever wondered where they all come from. The Hazel nut …hazel nuts are produced across Ireland every year, and many of our population are oblivious to this resource. The Burren for example is being taken over by hazel bushes as agricultural grazing declines.

The hazel is a multi-stemmed shrub growing to 10 metres and sometimes more. There are two main species that are grown and these and their hybrids form the many varieties of cobnut, e.g. Ennis Our native species is Corylus Avellana which grows throughout Europe into West Asia and North Africa. The other species is Corylus Mazima which is native to the Balkans and Asia Minor. Varieties have been developed in France, Italy, UK, Turkey, and the USA etc. Large crops of hazel nuts are harvested in these countries for domestic consumption and export.

Ireland was colonised by Hazel soon after the ice retreated. In earlier times it was used on a large scale as an important source of food and shelter materials. The Hazel was greatly appreciated and revered in ancient Ireland. It’s importance to the Celts is reflected in the mythology – Hazel being regarded as the tree of knowledge and one of the three magical fruiting trees, along with the apple and the oak, which together supplied all primary nutritional requirements.

The greatest incentive for planting Hazel today is the nutritional value and health benefits of the crop itself. Hazel has the potential to play a vital role along with other tree crops (other nuts and fruit), in a more sustainable form of food production.

Advantages of tree food crops over annual crops

All tree crops, Hazel included, build soil whereas most of our annual crops, such as wheat, silage, etc. deplete the soil. The cultivation of most of our annual grain and legume crops involve creating bare soil. In ecological terms bare ground is a disaster in nature and the planted crops then attempt to repair the damage, this being their original ecological role. This process is repeated year after year. Whether by ploughing or spraying poison (herbicide) nutrients are leached and soil eroded. the natural progress of ecological evolution is stunted and the land is prevented from reaching its full potential. In contrast trees are much further along this ecological process, and forest are highest evolved habitat which build soil and absorb carbon year after year, thus increasing natural capital as well as biodiversity.

The advantages of growing staple crops from trees and shrubs over annual plants include:

1. No tillage required, therefore less soil erosion, less leaching of nutrients and less energy inputs

2. The build-up of soil through leaf litter and the capture of carbon in soil and the plant itself

3. Increased leaf area meaning greater capture of solar energy allowing the plant to

4. Better resistance drought and flood.

Nutritional value of hazelnuts and health benefits

Nutritionally Hazelnuts/cobnuts are 65%-70% oil /fat most of which is mono-unsaturated, 15% carbohydrate and 15-20%protein with good amounts of calcium, phosphorus and potassium. It has been suggested that they are a suitable raw material to replace soybeans and soya products, especially as they do not have the drawback of phytoestrogen content which has led to recent concerns regarding the safety of soya products. Recent research has shown that Cobnuts contain only small amounts of Omega 3 fatty acids but their proven health benefits derive from vitamins, etc. (see reference).

Interestingly American researchers have discovered small amounts of tazanes in hazel foliage and bark. Taxanes are the raw material for the new anti-cancer drug, Taxol currently derived from the Pacific Yew tree. It is suggested that these compounds may also be present in the fruit of the Hazel. Research in this area is ongoing.

Pests and Diseases

Hazels and Cobs are hardy trees that are rarely seriously troubled by disease. The main pest in certain parts of the country is the introduced Grey Squirrel species which takes the nuts before they are ripe. The best control is to trap and dispose of them. It is illegal to release squirrels into the countryside. However squirrel is a very sustainable and reportedly tasty source of protein.

Growing conditions for Hazel

Hazels/Cobnuts are very easy to grow, thriving in all but the most difficult of conditions. However, like most tree crops, better conditions result in better crops. It is a common mistake to plant trees on the poorest site, and then condemn the trees for not doing well. Poorer land for timber with occasional cropping and treat your main tree crops to better land.

The ideal site for a cob tree is a sunny, sheltered spot but partial shade is tolerates and may be necessary in an exposed site. In fact Cobs grow well and fruit reasonably well on the North side of a windbreak. Most soils are suitable, alkaline soils are the optimum but clays and acid loams are tolerated. Hazels do not thrive on unimproved acid peatland. We have also noticed that they do not thrive riparian zones.

Hazels are monoecious, meaning that they carry both male and female flowers. However because flowering times seldom coincide on individual plants they may be regarded as self-sterile.

Pollination is by the wind and two or more different varieties are required for fruit. A hedge of nearby native hazel will usually pollinate your cobnut trees. The female flowers are tiny red tassels on the tips of the buds, the male flowers are the familiar ‘lambs tails’ of early spring. Flowering occurs from January to March and poor weather at this time may affect the crop. It seems a short period of dry weather allows adequate pollination.

Productivity

Yields are variable from year to year and individual trees can yield from 3-6kg of nuts, sometimes up to 10 kg. Mature orchards in Kent, UK yield 400-800kg/acre using older, less fruitful varieties so potentially higher yields are possible.

Plants are usually spaced about 5 metres apart but can be planted closer t together in a hedge row. Pruning has traditionally been intensive consisting of forming a bowl-shaped bush on a single stem whilst cutting back side shoots in the winter and breaking as hard long side shoots in August.

Some growers advocate letting trees grow in a more natural form on multiple stems thus requiring less labour input. Yields between the methods are comparable as the main limiting factor to crops seems to be soil conditions. Thus feed the soil and let the leaf litter, which is high in nitrogen and phosphorus, recycle the nutrients.

Harvesting and Storage

COBNUT VARIETIES

All cobnut varieties are clonally reproduced as they do not come true from seed. These improved varieties usually produce well, sometimes exceptionally, and are an option for cheap, large scale plantings. There are hundreds of varieties. The listing below includes only the varieties we are currently growing at Woodkerne Nurseries in Skibbereen, Co. Cork in the South west of Ireland.

Butler: A vigorous tree producing good crops of large nuts and plenty of male flowers

Corable: Another vigorous tree giving regular yields of large nuts in mid-late season.

Cosford: Old variety with medium size nuts of very good flavour, cropping well.

EMOA 1: New variety that has not cropped yet, nuts are reportedly very large, and very productive.

Ennis: A variety from the United States giving good crops of very large nuts.

Gunslebert: Smaller tree producing regular crops of medium sized, well flavoured nuts

Halls Giant: Large nuts, plentiful male flowers and fairly vigorous tree, tree, heaviest cropper in some UK trials.

Kentish Cob: Traditional UK variety, fair yields of medium sized tasty nuts.

Longue de’Espagne: Similar to Kentish Cob with slightly longer shaped nuts, produces when very young.

Pearsons Prolific: Heavy, regular cropper of medium -sized nuts of good flavour, vigorous tree.