Initially this drew on the WA govt material, it’s being rewritten. The sourcing your trees could have its own Wiki page.
Once you’ve worked out what varieties of truffle you will plant, you will need to source your inoculated trees. Most nurseries sell year old seedlings (in Spain that’s mandated by law as the optimum size) so you’ll need to allow that time frame.
Have you done your Soil preparation including weed removal, pH adjustment and deep ripping ? It can take more than a year for the pH levels to be right, so it is wise to allow two years to get the pH balance stable. Of course you’ll be impatient, but you (or your children) will spend the next 25 years looking after these trees, so preparation is important.
It is also recommended that irrigation infrastructure is completed before planting. This ensures that no further heavy machinery is taken into the truffle orchard where it can cause damage to trees and root systems or soil compaction. Soils should be ripped before planting to break up any hard clay or compacted layers and improve drainage.
Sourcing your trees?
In Australia and New Zealand inoculated trees are commonly hazelnuts (Corylus avellana) or oaks, such as the deciduous English oaks (Quercus robur) or the evergreen Holm oak (Quercus ilex). In most cases commercial harvesting of the hazelnuts is balanced against the disturbance and compaction to the soil at a time when truffles have formed. For small plantations, this practice would be worth considering, with pressure on truffle prices, maximum crop returns for your paddock should be sought. There are also conflicts with current fertilisers, pesticides, tilling and pruning practices to suit nuts. There are varieties that may be better for this mixed use and T.borchii seems to be very tolerant to those practices.
Inoculated hazelnut and oak seedlings for commercial growers are available from specialised nurseries. If planting stock is being brought from interstate into Western Australia or Tasmania, quarantine biosecurity requirements must be met. Talk to your tree supplier.
See our Tree inoculation section for the reasons why you should be ensuring your seedlings are sufficiently colonised and DNA tested to ensure there are no other varieties present than the ones you want.
It is virtually impossible to remove contaminants such as T. brumale from an orchard. Further, it is not financially feasible to attempt to re-inoculate mature trees if they lack the truffle fungus at planting out. See details of one attempt here.
Varieties available commercially are;
- Tuber Melanosporum (Black Winter Truffle aka. Perigord Truffle),
- Tuber aestivum (Summer Truffle which is identical to Burgundy or Autumn Truffle just harvested earlier),
- Tuber borchii (Bianchetto (aka. Little White)
- Tuber magnatum (Alba White Truffle) is also produced by some nurseries, but yet to achieve production anywhere in the world These are typically inoculated on Quercus (oaks), Coryllus (hazels) and borchii on Pinus (stone pine)
The Quercus varieties Faginea and Coccifera are going to grow in importance as they are both low shrub-like trees and are useful as an inter-row variety that will allow more sunlight to reach the ground as the bigger varieties grow and the canopy closes.
How many trees to plant?
You’ll read the financial arguments in other sections of the Wiki for plantation size and the issues of large mono-cultures and their difficulties of pest and disease control, but often your decision will be based on what size paddock you have available, how many people will be available to plant and then ongoing labour for weed control, pruning and harvest. If this is a commercial venture you’ll have worked out what your labour costs will be and the expected return (refer to our spreadsheet)
Most crops have a sweet spot for what’s called ‘lifestyle’ growing. For example, the maximum number of trees that two people can look after with a bit of outside help is 100-500 trees for olives for example. We’ve most often heard the suggestion of 300-700 trees for truffles. You can adjust that if there are other family members to actively assist, or if you have an outside income and can employ help.
Start with a grid.
You will have to drive a tractor between the rows for the life of the truffière. So you need access on one side of the trees, or both if you are using cross ripping and cultivator tilling. We have probably traditionally planted too close, and our oldest plantations in Tasmania and West Australia now need work to open the canopy to allow soil warmth in summer.
Many plantings were originally done with a mixture of oaks and hazelnuts, with a hazel or two planted between each oak, the assumption being that the hazels will reach their ‘use by date’ after twenty years and be removed to allow the oaks to grow. Chopping out a productive hazelnut tree will be hard to do, especially if the neighbouring oak is non productive. The oaks require less initial maintenance and pruning, but in the long term they become difficult due to height, and it may also be possible to maintain the youth of a hazel plantation by training new trunks/shoots. Therefore it comes down to a personal decision on long term maintenance workload versus diverse planting flexibility.
The number of trees per hectare can easily be calculated by dividing 10,000 (there are 10,000 sq meters in 1 hectare) by the two planting distances. For example the spacing 3 x 5m will give 667 trees per hectare, a 6 x 6m spacing will use 278 trees per hectare. Interplanting with junipers and rosemary or lavender will require wider spaces.
Planting
Soil preparation including weed removal, pH adjustment and deep ripping should begin well in advance of planting. It can take more than a year for the pH levels to be right, so it is wise to allow two years to get the pH balance stable at between 7.5 and 8. Of course you’ll be impatient, but you will spend at least the next 25 years looking after these trees, so preparation is important.
It is also recommended that irrigation infrastructure is completed before planting.
Whatever the planting density, the number of trees per hectare can easily be calculated by dividing 10,000 by the two planting distances. For example the spacing 3 x 5m will give 667 trees per hectare, a 6 x 6m spacing will need 278 trees per hectare. Eg. 10000 divided by 36 = 277.7
Making holes
A hand auger of 10cm wide and 250cm deep can be used but planting a few hundred trees will still need a lot of help (you can offer them a truffle in ten years time if they’re still friends.)
Tractor powered post-hole diggers can be used for tree planting, but they tend to form holes with smooth, glazed sides that will not allow root penetration into the surrounding earth, causing the seedlings to die from lack of water and nutrients. If post hole diggers are used as a last resort, ensure that the sides are broken up (with a crowbar or shovel) in anything but a light sandy soil. (source WA Dept of Agriculture)
The planting holes section is questionable, I wouldn’t propose this method at all. A well prepared paddock will have been cultivated 20-30cm deep at least, and any deeper prep would best be done via a rip line, if there has been enough ripping done to ensure its not become a water filled trench.