Chestnuts

Markets

Overseas, chestnuts are readily processed into a wide range of user-friendly long-life products designed for everyday consumption, and are available on supermarket shelves. By developing a range of processed products, the New Zealand chestnut industry hopes firstly to avoid the pitfall of over reliance on fresh nuts, which could become over supplied at some stage, thus crashing growers’ returns, but secondly and more importantly, to develop added-value products to build the industry in New Zealand.

Overseas processed products include peeled frozen free flow chestnuts, canned whole peeled chestnuts, vacuum-packed whole peeled chestnuts, sugared confectionery, purees, ice cream, baby foods, chips, yoghurts, dried whole chestnuts, flour for bread and biscuits, etc. Many products are sold on the health market for premium prices.

Other products include chestnut fettuccine, chestnut-flavoured chocolate, chestnut puree and chestnut flour, which retails in New Zealand for $27–38/kg.

Currently New Zealand nuts are mostly exported and the local market is fully supplied, but expanding. A recent development is the production of chestnut meal in New Zealand, for the food industry. Overseas markets pay highest prices for processing quality nuts, but this has not yet happened here.

Chestnut timber is also highly sought after overseas. Timber from Castanea sativa is naturally ground durable. However, the lifespan of chestnut trees can be anywhere from 200–800 years, with nut output peaking at 35–50 years.[1]

A new product category may be possible, using chestnut waste as animal feed. From 2012–2014, a joint MPI Sustainable Farming Fund R&D project, partly funded and supported by the NZ Tree Crop Association, was completed.[2] Inspired by overseas studies, this project looked at how the inclusion of even a relatively small amount of high-tannin ‘ingredients’ in animal feed, in this case chestnut shell and pellicle (inner skin) waste, could bring about much-improved animal health in a variety of animal species and, in particular, a significant reduction in problems caused by intestinal worms and harmful gut bacteria, potentially improving livestock health and condition and reducing or even eliminating the need for chemical intervention and/or antibiotic use, along with reduced levels of N & P excretion and methane production.

A key finding was that when included in the normal daily feed for alpacas (alpacas being especially sensitive to diet-, feed- and worm-related problems), chestnut by-product/waste produced a significant benefit in terms of animal health (via reduced worm counts), even when included only at low rates. No chestnut-fed animals needed worming over the trial period.

This may open up a new product category for chestnuts and significantly, with important benefits to the agricultural industry.

[1] ‘The Chestnut Tree’, Pierre Laszlo http://www.pierrelaszlo.com/science-writings/plant-of-the-month/9-the-chestnut-tree

[2] ‘A New High-Tannin Animal Stockfood System’, David Klinac, The Chestnut Grower, Winter 2016 http://www.chestnutgrowers.org/2016january.pdf

Production

Chestnut trees are small to large deciduous trees, meaning the trees lose their leaves and become dormant to withstand cold winters. The large edible seeds are called chestnuts and are produced annually on the tree inside a prickly case called a burr. In the autumn, when ripe, the burr splits open allowing the chestnuts to fall free, onto the ground.

The most commonly planted varieties are the Euro/Japanese hybrids, known by the following numbers: 1002, 1005 and 1015. All are characterised by rapid vegetative growth when young and are early bearing. Nut production will commence in the second or third season after planting if desired. To a much lesser degree there are plantings of the Japanese chestnut varieties Mayrick King, Mayrick Queen and 902, which appear to crop more heavily in warmer areas such as the coastal Bay of Plenty, and northern regions. The Japanese chestnut varieties often produce the largest nuts, but the trees are not always as hardy as the Euro/Japanese varieties.

All these varieties produce chestnuts with difficult-to-remove inner skins. The easiest way to prepare them for cooking is by using specialised chestnut peelers.

Layout

The most common spacing pattern is to initially plant the orchard at 6 x 6 m (256 trees/ha) and when the trees begin to intergrow, to thin out the temporary trees to a final spacing of 12 x 12 m (64 trees/ha). Alternatively some growers plant at 12 x 12 m (64 trees/ha), particularly where the land between the trees can be intercropped, although selection of the secondary crop would require nitrogen leaching analysis and a nutrient management plan.

Flat to gently sloping land is preferred for the orchard for ease of operation (especially mowing and harvest).

Chestnuts must not be thinned by cutting trees down. Dying roots could cause fungal infections in the remaining trees, therefore thinned trees must be dug out. Most growers are planting three varieties. Harvest must be by variety. Nut quality is modified by the pollinator. Very little is required in terms of day-to-day orchard management, except for mowing or spraying under the trees to enable easy nut collection.

Trees produce nuts from years three to four, with up to 50kg/tree by year twelve (100 kg max per tree). Given reasonable conditions, most orchards are capable of achieving around 4 tonnes/ha once the trees reach maturity by year ten.

Nuts are harvested every two to three days, washed to remove orchard debris, (grass, etc.) and dipped to control surface moulds. They are placed in a cool store on the day of harvest.

When the nuts fall to the ground, they must be harvested within a day to avoid deterioration. The prickly burrs can be a problem, so thick gloves and protective shoes are necessary. Various machines (vacuum and ‘hedgehogs’) can be used to pick up the nuts. After harvest, the nuts must be chilled for fresh sale or processed, dried, etc. reasonably quickly and are usually stored in cool stores.

Infrastructure

Expenditure on infrastructure depends on whether a farm’s existing assets can be modified for re-use.

Basic gardening equipment such as a mower, weed sprayer, etc. is all that is needed for most chestnut plantings. Infrastructure may grow to include packing shed, cool store, implement shed, irrigation, shelter belts, fencing and miscellaneous equipment.

Fencing is required to keep out pests (e.g. rabbits) from eating young trees.

Nitrogen Leaching: Low

Environment

Fertiliser

Chestnut trees respond well to a balanced fertiliser programme, whether that’s organic or artificial. They need good supplies of nitrogen, potassium and magnesium in particular. Fertiliser should be applied in early spring and again mid-summer – ‘a little and often’ rather than in one heavy application, which can cause root burn and is usually largely wasted.

No research is available for nitrogen leaching of a chestnut orchard, however it is considered to be in the low range. Any land use change to a chestnut orchard planned for the Lake Rotorua catchment would need to be modelled for nitrogen leaching.

Pests/diseases

Overseas, there are many serious and crippling pests and diseases that often make chestnut production uneconomic. New Zealand is fortunate to be mainly free of most of these serious problems, and this is the reason for the strict border controls and lengthy quarantine periods placed on the introduction of overseas chestnut plant material, including seeds.

People travelling overseas should not bring back fresh chestnuts, as many of these pathogens are spread by contaminated chestnuts that appear quite healthy. In New Zealand, the main problems are:

• Root rot caused by the soil­-based fungal disease Phytophthora cinnamomi which usually kills the tree (at any age) and is more prevalent on heavier soil types. Trees can be infected at the nursery stage, so growers should ensure their nursery supplier is certified as meeting the nursery standards as specified by the NZ Chestnut Council. Control with fungicides is difficult, however the use of trunk injections or foliar sprays with phosphorous acid as a preventative for healthy trees is currently under trial evaluation and showing promising results. To reduce exposure to root rot diseases it is not recommended that orchards are established on poor-draining soils that are prone to waterlogging.
• Infection of the nuts while on the tree with the fungal diseases Phomopsis and Botrytis (and other fungi) can lead to rotten nuts at harvest and can cause serious losses even under cool storage.
• Puriri moth, grass-grub beetles, cicadas and possums can cause serious damage to young trees. The grass-grub beetle will eat the soft new-season foliage of chestnut trees in the late spring when they fly at dusk, often in quite staggering numbers. Young trees may be completely stripped. Possums are especially damaging, eating the bark, leaves and breaking branches. They relish eating the nuts when they fall to the ground at harvest. Rabbits and hares will eat the bark of young trees.

Climate

In general, the more humid conditions found in the North Island produce a bigger tree and bigger final nut. However, humidity also increases the chance of root rot and other diseases in the tree.

Winter chilling and frosts

Frosts are generally not a concern to chestnut trees as they flower late in the spring, although late spring frosts can burn new-season foliage. Care must be taken with early autumn frosts, as these can affect both foliage and fruit.

Rainfall and irrigation

Irrigation and shelter is helpful in exposed situations. Irrigation can make establishment easier and increase crops. A hot summer (i.e. 30°C) is helpful to ripen nuts. Regular rainfall is required over summer-autumn months, otherwise irrigation may be required. Chestnut trees do use a lot of water, especially near harvest, as they are filling out the nuts.

Wind

Although chestnut trees are reasonably wind hardy and demand a high light intensity to promote female flower production, they grow and produce much better with effective shelter from strong prevailing winds, especially over late spring and early summer when new foliage is at its softest and prone to windburn. Effective shelter is most needed when the trees are first planted and over their next few years, when vegetative growth is at its maximum. Ideally, shelter lines should be planted one to two years before the orchard trees.

Soil

Soil type needs to be free draining year-round, down to 2 metres, with an acid pH of around 5.5–6.5. Heavier, poorly drained soils increase the likelihood of root rot problems (Phytophthora spp). Soil fertility is not usually a problem.

Weed control

Weed control under trees is essential to allow nut pickup. Grass in the rows is usually mowed. Growers thinking of grazing sheep between the trees should be very careful – sheep will and do eat the bark from around trees, which kills them by ring-barking.

Returns

Estimating grower returns and production levels per hectare is easier said than done, given the vagaries of the market place from year to year and the wide variation in tree performance from one site to another.

However, growers’ gross returns (at gate) can range from $2.00/kg for local market to $3.00/kg for fresh export or processing, depending on size or grade of the nuts, with the larger or earlier season nuts usually fetching a premium. Small nuts are difficult to sell at a profit on the fresh fruit market and are utilised for processing into value-added products.

Harvesting costs range from 50c to $1.00/kg depending on tree age. Given reasonable conditions, most orchards are capable of achieving around 4 tonnes/ha once the trees reach maturity by year ten. Average gross returns at maturity (calculated at say $2.50/kg average) would translate to $10,000/hectare.

Further processing by drying, crumbing or making into other value-added products would add to the income.

Compared to many horticultural crops, a chestnut orchard is cheap to establish and maintain, and has a low time input requirement (except at harvest). This allows most orchard owners to follow additional vocations as well.

Useful Links

New Zealand Chestnut Council

David Klinac, Executive Director
10 June Place, Hamilton 3216
T: 07 856 9321
E: dklinac@xtra.co.nz
Website: www.nzcc.org.nz

Ray Knowles
P O Box 411, Hastings 4156
T: 06 874 3029
E: ray.knowles@gmail.com

Information sources:

Chestnut Fact Sheet, New Zealand Chestnut Council (http://www.nzcc.org.nz/)

Chestnut Crop Summary, New Zealand Tree Crops Association Crop Guide (http://www.treecrops.org.nz/crops/nut/chestnut/)

Anavon Orchard, (http://chsntz.weebly.com/value.html)

Chestnut Traders, (www.chestnut-traders.co.nz)

FAOSTAT, United Nations Food and Agricultural Organisation (http://www.fao.org/faostat/en/#data)

Infoshare – Statistics NZ (http://www.stats.govt.nz)