Spring maintenance in Tuber melanosporum plantations, is carried out in the post-harvest period of early to mid-spring. During this six week period, aim to complete all pruning, buffer liming, if required, and soil cultivation, prior to the new seasons activity of the truffle fungus.
The fungus is basically dormant through winter, however, generally around mid-spring, the soil begins to warm, initiating the vegetative growth phase of the truffle mycelium. This is the time when the fungus begins to colonise the soil in search of mineral salts, water and to establish mycorrhizae with plant roots. It is also the precursor to the period in the second half of spring when first primordia (new truffles) begin to form.
In respect of this important underground activity, all maintenance tasks, that may in some way impact the soil, are best finished before mid-spring.
The first task will be pruning as this involves moving around the trees. This will inevitably create some compression (compaction) of the soil. When trees are young, pruning is minimal and its quite easy to stand back from the base of the tree. In future years it’s a little more difficult, but still advisable, to minimise soil impact.
When pruning, particularly in the area of the brulé, try to stand as far away from the tree as is practicable. Using the right tools, such as long-handled loppers and pruning saws, will make this much easier to achieve.
If it’s determined by soil analysis that extra lime is required to raise pH in the plantation, then a perfect time to do this is after pruning and before cultivation. The cultivation then assists to incorporate the additional lime into the soil profile.
Soil cultivation generally starts in the 3rd or 4th season for Tuber melanosporum. It’s important to make sure you are finished this task no later than mid-spring. Not all farmers cultivate the soil around trees on an annual basis, however, this practice has been shown to have several benefits in the field, particularly in heavier soils.
The theory of light cultivation is primarily to loosen and aerate the soil in the outer third of the brulé and beyond. This tends to have a positive effect on mycelial development. It also assists truffles to form deeper in the soil profile, where they are more protected from exposure (drying out).
Other benefits include checking back of the roots to encourage branching, better water penetration and enhanced ecosystem biology. The tines of the cultivator only penetrate the soil to 150mm (6 inches).
When these spring maintenance tasks are completed, the soil in the tree rows should then be left undisturbed, throughout the remaining Tuber melanosporum life-cycle, until harvest of course!