Hazelnuts: rational nutrition for fruit quality

Today Italy ranks second in the world among hazelnut producing countries, after Turkey, and first in the European Union. Although the quality of hazelnuts produced in Italy has always been undisputed, the increase in production, their diffusion in areas new to hazelnut cultivation, and the threats posed by climate change, by new parasites such as Corylus avellana, and by potential critical issues relative to land, force us to reflect on the adoption of the most appropriate cultivation techniques, with particular focus on fertilization and maintaining the best chemical and physical conditions of soil in hazelnut groves.

According to ISTAT data, in 2021 hazelnut trees in Italy were grown across almost 90,000 hectares, a sharp increase compared to 73,000 in 2015. The regions where hazelnut cultivation is most concentrated are Piedmont, Lazio and Campania, which are the areas that have also seen, over the same time span, the largest increase in hazelnut grove surface area (+7,500 hectares in Piedmont, +5,500 in Lazio, + 1,400 in Campania).

Potential Italian production in 2021 was around 150,000 tons, but the actual production was less than 90,000 (compared to more than 140,000 in 2020). The drop in production recorded in 2021 is mainly due to the rather unfavourable weather trend and the increasing spread of the Asian bug (Halymorpha halys), alongside other insects that normally infest the hazelnut tree; as well as the “new” powdery mildew, Erysiphe corylacearum, more aggressive than common hazelnut powdery mildew (Phillactina corylicola) and for which there are no registered active substances yet.

The almost uninterrupted growth that characterized the areas cultivated with hazelnut trees in Italy since 2015 onwards, is due to several reasons.

Firstly, in order of importance, is the market factor: the demand for hazelnuts for fresh consumption and industrial transformation has increased strongly globally. In Italy, in particular, several supply chain projects have arisen, partly led by the processing industry (Ferrero, Nestlè, Loacker, Novi…), which have not only made the cultivation of hazelnuts attractive by virtue of the guarantee of product outlet and profitable prices, but they have also brought a significant innovative push to the sector, which the production sector has benefited from. Incidentally, it’s worth mentioning that hazelnuts are also used in the cosmetics industry and that the shells can fuel stoves, thanks to their high heating value.

The concomitant crisis of certain fruit crops has given a further boost to hazelnut crops in our country, placing the hazelnut among the replacement crops.

Finally, the hazelnut tree also meets the needs for more environmentally friendly crops, given the rather low water and nutritional requirements. The mechanization of crop operations is quite motivated and genetic improvement has led in recent years to the creation of an interesting varietal platform.

However, the rusticity and the ability to adapt this crop to limiting conditions must not lead us to believe that the quality of the product can be obtained without adequate crop care.

In a modern grove operating costs may be quite low, but some basic crop needs must be met to ensure the health and longevity of the plant, as well as the high-quality standards required by the market. The latter mainly concern the weight of the seeds, their size, health and the absence of defects such as double or absent seeds.

Given that hazelnut cultivation is more suitable for the hillside rather than prairies, from a weather perspective, this crop prefers areas with approximate annual average temperatures between 10 and 15°C and minimum winter temperature no lower than -8/-10°C, given that a very cold climate is harmful to the flowers that develop during January-February.

From a soil profile perspective, although the hazelnut tree is able to adapt to many different types of soil, medium-deep soils are preferable at a subacid pH and with a good supply of organic matter, especially not prone to water stagnation which favours root rot. For this reason it is advisable, especially if you opt for mineral fertilization and in particular during pre-planting, to ensure a good structure and sufficient porosity of the soil through the use of soil improvers.

From a nutritional point of view, in addition to the macroelements N, P and K to be distributed fractionally throughout the year (post-harvest, in essence, at the end of summer and in the spring, to foster the restart), the microelements B, Fe and Zn are considered the core elements in the cultivation of hazelnut trees, preventing physiopathies. Appropriate formulas (both mineral fertilizers and organic and organo-mineral fertilizers can be used) and correct methods of fertilizer distribution (both soil fertilization as well as foliar fertilization can be considered) are essential for guaranteeing the quality of the product.

There are numerous biotic adversities of the hazelnut tree, some more fearsome than others. Several cause greater damage in the presence of water and nutritional imbalances, which should therefore be avoided through proper soil management and, if required, through irrigation. Some of these adversities include Canker Disease (Cytospora corylicola) and the fearsome Hazelnut Bacterial Blight, a multifactorial syndrome – equal to what has been demonstrated by Kiwi Death – the symptoms of which begin in the spring and worsen during the summer, with the widespread yellowing and wilting of leaves. Hazelnut Blight is much more insidious in the presence of water imbalances and root asphyxiation.

In addition to the Agribios line of soil improvers, useful for restoring the proper organic matter content of soil where necessary, Agribios recommends adding the use of AGRIOLIVO BASIC, AGRIOLIVO 12.5.5 and ORTOFRUTTA SPECIAL 12.7.5. to the fertilization plan of hazelnut trees that includes organo-mineral products.

These three products provide, in a single step, together with the mineral fraction containing slow-release nitrogen, phosphorus and potassium, as well as a significant amount of highly organic humidified matrix and meso elements. The organic matrix of AGRIOLIVO 12.5.5 and AGRIOLIVO BASIC consists of a mixture of the best quality humidified manure, naturally fermented for a total of 180 days in a covered and ventilated space. This long period of maturation reduces the moisture content, enriches the organic substance with humic acids, neutralizes the pH and sanitizes the mass, rendering it free of nematodes, salmonella, pathogens, antibiotics and weeds seeds.

When you need the elements supplied to act more quickly, these products can be paired with the line of liquid fertilizers used in foliar fertilization.