Hazelnuts are known to be beneficial for health: they are very rich in vitamin E, which our body requires every day, in mineral salts such as magnesium and manganese and in unsaturated fatty acids which prevent the so-called "bad" cholesterol. Of course, you must have a moderate consumption of hazelnuts, given their lipid content, otherwise goodbye to the line.
Even if the professional cultivation of the hazelnut is concentrated above all in a few regions, in our country there are spontaneous and cultivated plants everywhere. It is in fact a fairly simple cultivation with interesting income potential, but in order to be able to harvest good quantities of qualitatively satisfying hazelnuts, one must know how to protect the plants from possible adversities.
Fortunately, the hazelnut is still a fairly rustic species in itself and therefore also suitable for organic cultivation: it is not necessarily necessary to use chemicals to keep the hazel grove healthy.
The main adversities from which the hazel can be affected are of an animal nature, especially insects that damage buds, fruits and vegetation as a whole. Diseases of a cryptogamic nature are less incisive, except in those years with somewhat anomalous climatic trends, such as excessive humid heat and persistent rains during spring. In these cases, fungal diseases can arise that damage shoots, root system and stems. Let's see which are the most frequent diseases and with which remedies allowed in organic farming we can eradicate them.
However, remember that pruning plants in a balanced way is, as always, a good preventive measure against the onset of diseases. The hazelnut is a shrub that produces many suckers and therefore tends to become an intricate bush, to promote air circulation inside the foliage, useful for avoiding the onset of fungal diseases, it is important to keep it regulated.
It is a disease caused by the Cytospora corjlicola fungus which is found above all in old hazelnut groves managed with mechanization, because it is favored by wood injuries caused by machinery. The first symptoms of this pathology are visible as reddish-brown spots on the stems, below which the woody tissues necrotize until the infected part is completely dry. During the summer, we can notice redness on the branches, caused by the infectious inocula of the deadening pain, which must be removed with a healing pruning. In case of severe manifestation of this pathology we can treat the plants with cupric products, taking into account the indications given on the labels of the commercial product purchased. But in organic farming, you can also try a treatment with a more ecological hydroalcoholic solution of propolis.
The Piggotia coryli fungus is the main cryptogamic adversity in Piedmont hazelnut groves, but it can cause serious damage only in very humid and rainy years, especially in the positions of the valley floor where there is a stagnation of humidity. The gleosporiosis disease occurs twice a year. The first time in spring, borne by the browning and drying buds, and sometimes also by the terminal twigs. The second time occurs in late summer and affects the leaves, on which circular necrotic spots form. The most serious moment is the first, because it could compromise the formation of the crown. In areas where this disease is found, an autumn-winter treatment with copper-based products may be useful, always paying attention not to exceed the permitted dosages.
In the core, powdery mildew or bad white occurs on the underside of the leaves, with the typical dusty white efflorescences, while in correspondence with these on the upper side, yellowish spots are noted. Fortunately, the pathology is almost never serious, because it usually appears at the end of summer or early autumn, with an early fall of the leaves as a consequence. It may be useful to rake all these leaves away from the under canopy of a particularly attacked plant, so as not to encourage the infection to recur again the following year. If the disease were to present itself in the height of summer, it would be necessary to intervene by spraying the plants with sodium bicarbonate diluted in water or even products based on sulfur, the classic antioidic allowed in organic farming.
Armillaria mellea is a fungus that finds ideal conditions in soils that are very subject to water stagnation, in which it causes the root system of the stones to rot. The plants with the roots thus compromised by the pathology begin to show stunted foliage, of little vigor, and can even dry up. Initially in the subcortical areas of the root you can see the formations of the fungus, of white-cream color, but subsequently the fungal organs are also noticed externally. The best prevention of this problem is to ensure good drainage on the ground, generally the hilly hazelnut groves are not very prone to this pathology.
The stone can also be damaged by Xantomonas camprestris, a bacterium that causes the shoots to dry out, preceded by their downward curvature and the formation of some typical spots. Also in this case it is advisable to promptly eliminate the affected plant parts and possibly make a treatment with a copper-based product.