This is the final article in the series looking at our selection of varieties for our mixed orchard. Along with the various fruits, we are also planting a few nut trees. We began this last winter by planting a sweet chestnut, Marron de Lyon, and walnut, Broadview, and this year are adding almond and hazel trees. Along with the nuts, we are also experimenting with a small truffière. As hazel is one of the trees commonly used for the cultivation of various truffles, we can combine the nut harvest with the possibility of finding, in some years’ time, a few precious truffles.
First, though, to the almonds. These are closely related to peaches, being of the same subgenus, and unfortunately share susceptibility to one of their potentially crippling diseases, so called peach leaf curl, caused by fungus Taphrina deformans. Peach leaf curl, as the name suggests, causes pinkish red blistering and, where badly affected, curling of leaves, followed by defoliation. It typically strikes in the spring, affecting the young leaves. The defoliation is stressful on the plant and quite likely to ruin any chances of getting a decent crop.
For the fungus to develop, a certain amount of rain is needed and a continuous period during which the leaves remain damp. If protection from the rain can be offered until summer, peach leaf curl can be avoided. We have two peaches growing in one of the glasshouses, which are therefore free from this problem. They are old sorts, too, so probably have poor resistance. Some modern varieties have been bred to offer some resistance to peach leaf curl so can be planted in the open. Otherwise, some sort of temporary cover is recommended. This is easiest when grown as fans against a wall or other structure. Chemical control is also possible and, from what I have read, reasonably successful. Copper based sprays such as Bordeaux mixture, applied prior to bud break would be a possibility. These sprays have been on the edge of acceptability for organic gardening, but prevention seems to me to be much the preferred route.
It is a similar situation with almonds, and in the orchard environment, covering from the spring rains is not really a viable option. The selection of our almonds is limited, then, to modern sorts that show good resistance. These might also be better suited to our climate. Two varieties that appear suitable are Ingrid and Robijn. Both are self fertile so would give a crop on their own, but, as is often the case, planting two different varieties may well provide for improved pollination. Almonds are typically grafted onto the same sort of rootstocks as peaches. For the orchard, St Julien A should produce a reasonable sized tree.
Now to the hazels and the truffière. One might be forgiven for imagining that truffles are native only to France and Italy, where they seem to be most used. Whilst the finest sorts do come from distinct areas of France and Italy, truffles are more widespread, and some sorts are native to the UK. The finest truffles are the white truffle, Tuber magnatum, from the Piedmont region of northern Italy, sometimes referred to as the white truffle of Alba, and the black winter truffle or Périgord truffle, Tuber melanosporum, named after the region of south west France, although its native range covers wide areas of southern Europe. The white truffle is harvested in late autumn, and the Périgord truffle in the winter.
There are numerous other varieties, but none carry quite the same monetary or culinary value. Nonetheless, some are useful and very tasty. I have eaten many of the black summer truffles, Tuber aestivum, most often whilst visiting Tuscany; in fact, a dish of ‘tagliolini al tartufo’ is one of the first things I seek out. This truffle, which is harvested through summer and into early autumn, is actually native across Europe, including the UK. It is more or less identical to the Burgundy truffle, Tuber uncinatum, which seems to differ largely in its later harvest, from autumn to mid winter. There is also another white truffle, Tuber borchii, referred to as the Bianchetto or Marzuolo truffle, from the Italian for March, marzo, that can be harvested from mid winter to spring. This is supposed to have good culinary properties, and is another that can be found throughout Europe.
Interestingly, it is possible to cultivate truffles. Modern techniques have no doubt made the inoculation of saplings with truffle fungi much more reliable. Truffles grow on various woods, but hazel and oak are the most common for cultivation. Hazel is ideal for our orchard setting, as we will benefit from the nuts, and perhaps some hazel wood, as well as the possibility of finding some truffles.
Truffles generally seem to prefer a free draining, somewhat poor, calcareous soil, that is, a chalky or limey soil, with a pH from neutral to moderately alkaline. Although we have a free draining soil here, it is slightly acidic, so not really ideal for truffles. Nonetheless, I am keen to at least attempt to grow some, and if they do not flourish, at least the hazels will serve a useful purpose. Some adjustment of the soil with lime may well help. We bought seven truffle trees in total. Two each of the black summer truffle, Tuber aestivum, and the white Bianchetto truffle, Tuber borchii, from Seeds of Italy, www.seedsofitaly.com, and three of the black Périgord truffle, Tuber melanosporum, from UK based Mycorrhizal Systems, www.plantationsystems.com.
When the young trees arrived they were rather small, so instead of planting directly in the orchard, we potted them on to develop a little before they are planted out. Those from Seeds of Italy came potted while the others appear to have been grown in some sort of root trainer, being small in cross section but surprisingly deep. The soils seemed to be rather different too; the former was a solid, poor looking, gritty sort of soil, of the type they clearly prefer, whilst the latter came in soil that seemed to have a rather high clay content. No doubt both were suited to the truffles concerned.
I made up a potting mix of approximately equal quantities of top soil and peat free multipurpose compost. To this was added some fish, blood, and bone, as a slow release fertiliser, a handful of lime to increase the pH, and a good amount of horticultural grit to ensure free drainage. Whether this is a good mix or not, I have no way of knowing, but it seemed reasonable to me. When they have developed a more substantial root ball and more robust top growth, they will be planted out in the orchard. Further lime may then be added to the planting site to adjust for our slightly acidic soil.
I am fairly confident that we will see some of the black summer truffles, although it is likely to take five years or more before the first will be produced. The white truffle is also a possibility, but I must confess that the fine Périgord truffle seems like a long shot. In any event, without a trained truffle hound or a sow to hand, they will be a little tricky to find, but that is a problem for another day. The summer truffle, at least, seems to grow near the surface so might be spotted from a careful examination of the site. Whether we succeed or not, it is, though, an interesting thing to try and grow.