Black Truffle Orchard: Planting, Pruning and Pests

A truffle orchard is a plantation of host trees inoculated with black truffle, and what happens above ground decides what happens below.

This article follows the grower’s year in the orchard: how densely he plants, what he does in spring and autumn, who installs the water and why a chewed leaf matters.

It is written for people who already have trees in the ground, or are about to.

Layout: 300 trees per hectare

The grower plants 300 trees per hectare. He did not give a spacing pattern, only the density, and it is the only density figure he uses.

Everything downstream, from the plant order to the irrigation design, is sized from that number.

The calendar: pruning in spring, weeding in autumn

In the grower’s year, pruning is a spring job and weeding is an autumn job. In one recent year, he notes, everything fell in spring and the weeding was left for autumn.

Those are the two fixed points. The rest of the calendar is irrigation in summer and harvest in winter.

• Spring: pruning.
• Summer: irrigation.
• Autumn: weeding.
• Winter, December to April: harvest.

Pruning a truffle tree is not pruning

The grower does the pruning himself, and explains why: you have to know which branch, when, where and why. It is not the pruning a gardener does on a hedge.

One detail he insists on: the shears are disinfected between trees. Whoever helps him is put to that job first.

Irrigation: five companies in Spain, and everyone’s plumber

Irrigation for a truffle orchard is not irrigation for tomatoes. The grower counts about five companies in Spain that specialise in installing it.

What usually happens instead, in his telling, is that the owner calls an uncle who is a plumber, or a friend from the bar, or a cousin. That is the objection and the argument in one sentence.

Pests: what a leaf gall does underground

A client once sent the grower a photo of galls on a plant. He could not identify the insect from the picture, and neither could the pest specialist he consulted: there are 149 species in the Iberian peninsula that make identical galls. Until you see the insect, you do not know.

The damage from galls is mild in itself. The insect eats some leaf, the tree has less surface for photosynthesis, it makes less food, and so there is less for the fungus. The truffle is fed last.

Harvest: lifting without breaking

The orchard’s value is decided in its last metre. The dog must find the truffle without scratching it, and the person lifting it must not break it.

The grower has seen it happen with clients in the plot: a knife catches a corner, or the dog reaches a shallow truffle first, and it comes out split. A split truffle is worth a fraction of a whole one.

Where an orchard starts

Before any of the above, there is the plant. The page on truffle trees explains where it comes from, how the inoculation is checked and how many a hectare takes.

Where this article leads:

• Truffle Trees for Black Truffle (Tuber Melanosporum)
• Truffle Seedlings for a Black Truffle Plantation
• How to Grow Black Truffles
• Black Truffle Farming: What a Plantation Costs and Yields