Hazelnut-Associated Bacteria and Their Implications in Crop Management

In recent years, the cultivation of hazelnut (Corylus avellana) has expanded in several areas of Europe, Asia, Africa, and North and South America following the increased demand for raw materials by the food industry. Bacterial diseases caused by Xanthomonas arboricola pv. corylina and Pseudomonas avellanae are threats of major concern for hazelnut farmers. These pathogens have been controlled with copper-based products, which are currently being phased out in the European Union. Following the need for alternative practices to manage these diseases, some progress has been recently achieved through the exploitation of the plant’s systemic acquired resistance mechanisms, nanoparticle technology, as well as preventive measures based on hot water treatment of the propagation material. However, bacteria are not only agents of the biotic adversities of hazelnut. In fact, the application of plant growth-promoting rhizobacteria at the seedling level could enhance better performance of the tree. Likewise, endophytic and epiphytic microorganisms are considered to play a notable role in plant nutrition and protection, and their effects on hazelnut fitness deserve to be further investigated. Finally, bacterial associations may also be relevant in the post-harvest phase, particularly with reference to the processes of lipid oxidation and fat degradation suffered by the kernels after grinding