Autumn maintenance for Tuber melanosporum is important, particularly in terms of preparing for the new harvest season.
When we reach the autumn months, our psyche naturally tells us to relax a little in terms of irrigation, now that the summer heat is behind us. The definition between seasons however, is not what it once was. The transition from summer to autumn, is important in terms of maintaining irrigation, on an as needs basis.
We now understand that primordia (new truffles), may form at different stages, between late spring, through to early autumn, if environmental conditions are favorable. This means that whilst many ‘spring initiated’ truffles will have reached mature size by autumn, others will still be in varied stages of formation. All stages require some soil moisture for development and maintenance.
Naturally, seasonal change will eventually mean lowering temperatures, which will in turn lower soil moisture losses due to evaporation. Irrigations in autumn, will therefore, generally be required less frequently, however are no less important. When autumn settles into a pattern of intermittent rainfall, irrigations are no longer required.
The term ‘crowning’, refers to maturing truffles partially protruding up through the soil surface. This is generally visible in late summer and early autumn. Truffles that have formed closer to the surface, push up through the soil as they expand in size. If left unchecked, they are in part, exposed to the elements, surface pests and insects, generally resulting in loss of quality or complete drying out. Too many truffles forming close to the surface is not ideal. We’ll discuss maintenance methods to assist in avoiding this in another post.
Row by row visual inspections of the farm from mid summer onward are required to check for crowning truffles. They are usually easily seen, as a raised lump in the soil characterised by 3 to 4 cracks in the soil. Farmers use different mediums to cover crowning truffles, ranging from sand, lime and soil from nearby in the brule. The advantage of using a different colored material to cover the ‘lumps,’ is that they are easily identified later at harvest.
It’s a good idea when covering the truffles to have some water at hand. Cover them with around 20mm of medium, then lightly water it in, then apply another light covering. The water ensures the medium fills the cracks well and expels air pockets.
Weed control is also important as you move closer to harvest. A reasonably clean environment around the trees in autumn, particularly in close, is important for continued sunlight to the soil and for dogs to work effectively during harvest. Its important not to walk on the brule area, use mowers or remove weeds by hand around the trees at this time of the year. If truffles sitting in the soil profile are disturbed, either through movement of soil, or compression from above, they will most likely spoil.
If a weed ‘clean up’ is required, then spot spraying, using Glufosinate-ammonium in mid autumn should suffice for the season. This herbicide is only effective in temperatures above 18°C or 65°F.