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There are about twelve species of pines that bear edible nuts but the only important commercial species is Pinus pinea . Two other species, P. sabiniana and P. coulteri, produce large cones and offer some promise but both are much slower growing and the seed has a lower oil content than P. pinea.
The pine nut, Pinus pinea, is often called the 'Stone Pine' and sometimes the 'Umbrella Nut'. These names apparently come from the idea that this tree grows well in stony ground and also because at times it has a shape rather like an umbrella. The tree has many uses and is important in Italy, Spain and Portugal, with Italy producing the bulk of the world's supply of pine nuts.
The tree is fairly easily propagated from seed, preferably fresh seed. The optimum temperature for seed germination is about 17-19C. Temperature above 25C can inhibit seedling establishment while at temperatures below about 10C seeds become dormant. The best germination is obtained following planting in coarse river sand or pumice with about 25% moisture. The seed will rot if the medium is too wet. It is important to add mycorrhizal fungus gathered from under a stand of other pine trees, because in the absence of the fungi the trees are likely to suffer phosphorous deficiency and make poor growth. The fungi will also provide some protection from too wet or too dry conditions.
Once established, the young seedlings should not be over-watered. Once the nut shell has fallen off the seedlings can be transplanted into deeper containers. Care must be taken during any transplanting operation to avoid breaking the tap root as this will set back tree growth. After the seedling has reached a height of about 10 cm it becomes less sensitive to over-watering.
Trees are best planted at a spacing of 10 m for nut production or 5 m if planted as a shelter belt. Trees ultimately attain a height of 10 to 15 m. The species will grow on almost any soil other than a highly alkaline lime soil. If grown on permanently wet soils, such as peats, the tap root will fail to develop and the trees will blow over because of the heavy top growth.
Trees can be expected to start producing cones from about year 6, but one planting in Taranaki produced its first cones after 3 1/2 years. However, on poor soils production may not start until about year 12. No data are available on the production of nuts under New Zealand conditions but in Europe the annual yield of nuts is about 500 kg/ha. Each cone holds about 50 nuts and 100 kg of cones holds about 20 kg of nuts.
It is desirable to prune trees from year 3 to remove all the lower branches up to a height which permits access of tractors under the trees. Clearing of the lower branches facilitates the production and harvesting of the nuts and also enable sheep to graze the
area between the trees. With shelter belts the trees can be left unpruned although if the sides are sheared the branches will grow new tufts of needles.
Studies are still being undertaken in Italy on the effects of grafting which is being done with the object of producing more cones and better nuts. The preferred graft is a cleft graft done in mid-summer, although veneer side grafting is also practised. The rootstock used for grafting must be at least two years old otherwise delayed mortality occurs about two years after grafting. In addition to P. pinea the rootstocks used include P. radiata (80-85% success), P. halepensis and P. sabiana (60-70% success) and P. pinaster (20-50%). P. pinaster is considered a very important tree in Italy but is little grown in New Zealand.
Pinus pinea is utilised for a number of purposes in Italy, Spain and Portugal and these are briefly discussed below.
As shelter belts
The trees can stand strong winds and salt sea air, and once established will tolerate both wet and dry conditions. The trees develop low branches that remain green all their lives and lower branches tend to deter rabbits and hairs while the tree is young; apparently they do not like pine needles in their eyes. The strong tap root on this species is able to penetrate hard soil, a feature which helps it when there is competition for water.
For nut production
The pine nuts currently being imported into New Zealand are quite widely used for cooking , salads, confectionery and as a raw edible nut. Trees start to bear a crop of nuts after 6 to 10 years and this mean that a shelter belt can be a source of extra income. Harvesting is done using a hook on a long pole to pull the nuts from the tree. The cones are then spread on plastic or on concrete in the sun. On drying the cones open up and the nuts fall out.
For erosion control
The trees are very useful for erosion control in coastal areas as they tolerate salt-laden winds and will grow in both sands and clays. They also tolerate very hot summers and cold conditions down to 23C below freezing. During 1985, Italy had one of the coldest winters for many years and although large orchards of olives died, there was no apparent effect on the pine nut trees.
This is unlikely to be important under New Zealand conditions because a large number of trees are needed to make resin production worthwhile. It is of interest that when a tree is tapped for resin the nut production increases for a few years and then decreases sharply. This decease continues even if the taping is stopped.
Opinions vary on the value of the timber from P. pinea. In Italy it is used for pallets and packing material but in Portugal, where there is a shortage of timber, it is used for many purpose. Sawmills will not accept trees of P. pinea that have been tapped because of the likelihood that nails or other pieces of metal may be left in the tree.
As the growth of branches commences close to the ground, the lower branches can become large if left unpruned. The extent of the growth of the lower branches is very much determined by the spacing between trees. Removal of the lower branches and removal of a second leader, if it develops, also improves the value of the tree for timber.
As these trees do well in sand they can be planted near beaches and in parks. They give very good shade when the lower branches are pruned and the tree grows into an umbrella shape.
In both Italy and Portugal, owners of blocks of P. pinea trees near a beach often use them to obtain several sources of income. They earn money from the nuts and the resin, and also often charge a fee for visitors to park their cars under the trees. Some of the orchards are also used as caravan and holiday parks in the summer.
I wish to record my gratitude to both the Italian and Portuguese Governments who assisted me by providing both information and books on pine nuts.
Any claims made by authors in the Australian New Crops Newsletter are presented by the Editors in good faith. Readers would be wise to critically examine the circumstances associated with any claims to determine the applicability of such claims to their specific set of circumstances. This material can be reproduced, with the provision that the source and the author (or editors, if applicable) are acknowledged and the use is for information or educational purposes. Contact with the original author is probably wise since the material may require updating or amendment if used in other publications. Material sourced from the Australian New Crops Newsletter cannot be used out of context or for commercial purposes not related to its original purpose in the newsletter
Contact: Dr Rob Fletcher, School of Land and Food, The University of Queensland Gatton College, 4345; Telephone: 07 5460 1311 or 07 5460 1301; Facsimile: 07 5460 1112; International facsimile: 61 7 5460 1112; Email:firstname.lastname@example.org
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originally created by:GK; latest update 6 June 1999 by: RF