The hazelnut is a food known to be beneficial for health: it is rich in vitamin E, which our body needs daily, in mineral salts such as magnesium and manganese, and in unsaturated fatty acids which prevent the so-called “bad » cholesterol. Naturally, a moderate consumption of hazelnuts is necessary, given their lipid content, otherwise the line is over.
Although professional stone farming is mainly concentrated in a few regions, wild and cultivated plants can be found all over our country. In fact, it is a fairly simple crop with an interesting income potential, but to harvest good quantities of quality hazelnuts, it is necessary to know how to protect the plants from possible adversities.
Fortunately, the hazelnut itself is quite hardy and therefore also suitable for organic cultivation: it is not necessarily necessary to use chemicals to keep the hazelnut healthy.
The main adversities with which the kernel can be affected are of an animal nature, in particular, insects that damage shoots, fruits and vegetation as a whole. On the contrary, diseases of a cryptogamic nature are less incisive, except in years with a somewhat abnormal climatic tendency, such as excessive humid heat and persistent spring rains. In these cases, fungal pathologies can occur and damage the shoots, root system and stems. Let’s see which can be the most frequent diseases and with which remedies authorized in organic farming they can be eradicated.
Remember, however, that a balanced pruning of the plants is, as always, a good preventive measure against the appearance of diseases. The hazel is a bush that produces many suckers and therefore tends to become a complex bush, to promote air circulation in the foliage, useful in preventing the appearance of fungal diseases, it is important to keep it regulated.
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It is a disease caused by the fungus Cytospora corjlicola, which is mainly found in old mechanized hazelnut trees, as it is favored by damage to the wood caused by machinery. The first symptoms of this pathology are visible in the form of reddish-brown spots on the stems, under which the woody tissues become necrotic until the infected part dries out completely. During the summer, one can notice a redness on the branches, caused by the infectious inoculations of the disease of the detachment, which must be eliminated by a curative pruning. In the event of a serious manifestation of this pathology, we can treat the plants with copper-based products, taking into account the indications on the labels of the commercial product purchased. But against the disease of detachment in organic farming one can also try a treatment with a more ecological hydroalcoholic solution of propolis.
The fungus Piggotia coryli is the main cryptogamic adversity of Piedmont hazel trees, but serious damage can only be caused in very humid and rainy years, especially in valley bottom positions where stagnation of humidity occurs. The disease of gleosporosis occurs twice a year. The first time in the spring, it affects darkening and drying shoots, and sometimes also terminal branches. The second time occurs at the end of 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 foliage. In areas where this disease occurs, autumn-winter treatment with copper products can be useful, always taking care not to exceed the permitted doses.
In hazel, powdery mildew or very white powdery mildew appears on the underside of the leaves, with the typical powdery white efflorescences, while in correspondence of these, on the upper side, yellowish spots are observed. Fortunately, the pathology is almost never serious, since it usually appears in late summer or early autumn, with the consequence of early leaf fall. It can be useful to pull out all these leaves under the canopy of a particularly attached plant, so as not to favor a reinfestation the following year. If, on the other hand, the pathology occurs in mid-summer, it would be necessary to intervene by spraying the plants with sodium bicarbonate diluted in water or also sulfur-based products, the classic antioídico authorized in organic farming .
Armillaria mellea is a fungus that finds ideal conditions in soils that are very prone to standing water, where it causes the root system of stones to rot. Plants with roots so compromised by pathology begin to show stunted foliage, low vigor and may even dry out. Initially, in the subcortical areas of the root, the fungal formations can be noticed, creamy-white in color, but later the fungal organs can also be noticed externally. The best prevention of this problem is to guarantee good soil drainage, normally hazel trees are not very prone to this pathology.
The pit can also be damaged by Xantomonas camprestris, a bacterium which causes the shoots to dry up, preceded by their bending downwards and the formation of a few typical spots. Also in this case, it is advisable to quickly remove the affected parts of the plant and, if necessary, to treat it with a copper-based product.